Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

PubMed

Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng

2005-04-01

This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

Doubly-excited pulse-waves on flowing liquid films: experiments and numerical simulations

NASA Astrophysics Data System (ADS)

Adebayo, Idris; Xie, Zhihua; Che, Zhizhao; Wray, Alex; Matar, Omar

2016-11-01

The interaction patterns between doubly-excited pulse waves on a flowing liquid film are studied both experimentally and numerically. The flowing film is constituted on an inclined glass substrate while pulse-waves are excited on the film surface by means of a solenoid valve connected to a relay which receives signals from customised Matlab routines. The effect of varying the system parameters i.e. film flow rate, inter-pulse interval and substrate inclination angle on the pulse interaction patterns are then studied. Results show that different interaction patterns exist for these binary pulses; which include a singular behaviour, complete merger, partial merger and total non-coalescence. A regime map of these patterns is then plotted for each inclination angles examined, based on the film Re and the inter-pulse interval. Finally, the individual effect of the system parameters on the merging distance of these binary pulses in the merger mode is then studied and the results validated using both numerical simulations and mathematical modelling. Funding from the Nigerian Government (for Idris Adebayo), and the EPSRC through a programme Grant MEMPHIS (EP/K003976/1) gratefully acknowledged.

Origin of the double- and multi-pulse structure of echolocation signals in Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientialis)

NASA Astrophysics Data System (ADS)

Li, Songhai; Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari

2005-12-01

The signals of dolphins and porpoises often exhibit a multi-pulse structure. Here, echolocation signal recordings were made from four geometrically distinct positions of seven Yangtze finless porpoises temporarily housed in a relatively small, enclosed area. Some clicks demonstrated double-pulse, and others multi-pulse, structure. The interpulse intervals between the first and second pulse of the double- and multi-pulse clicks were significantly different among data from the four different positions (p<0.01, one-way ANOVA). These results indicate that the interpulse interval and structure of the double- and multi-pulse echolocation signals depend on the hydrophone geometry of the animal, and that the double- and multi-pulse structure of echolocation signals in Yangtze finless porpoise is not caused by the phonating porpoise itself, but by the multipath propagation of the signal. Time delays in the 180° phase-shifted surface reflection pulse and the nonphase-shifted bottom reflection pulse of the multi-pulse structures, relative to the direct signal, can be used to calculate the distance to a phonating animal.

Baird's beaked whale echolocation signals.

PubMed

Baumann-Pickering, Simone; Yack, Tina M; Barlow, Jay; Wiggins, Sean M; Hildebrand, John A

2013-06-01

Echolocation signals from Baird's beaked whales were recorded during visual and acoustic shipboard surveys of cetaceans in the California Current ecosystem and with autonomous, long-term recorders in the Southern California Bight. The preliminary measurement of the visually validated Baird's beaked whale echolocation signals from towed array data were used as a basis for identifying Baird's signals in the autonomous recorder data. Two distinct signal types were found, one being a beaked whale-like frequency modulated (FM) pulse, the other being a dolphin-like broadband click. The median FM inter-pulse interval was 230 ms. Both signal types showed a consistent multi-peak structure in their spectra with peaks at ~9, 16, 25, and 40 kHz. Depending on signal type, as well as recording aspect and distance to the hydrophone, these peaks varied in relative amplitude. The description of Baird's echolocation signals will allow for studies of their distribution and abundance using towed array data without associated visual sightings and from autonomous seafloor hydrophones.

Specializations for aerial hawking in the echolocation system of Molossus molossus (Molossidae, Chiroptera).

PubMed

Mora, E C; Macías, S; Vater, M; Coro, F; Kössl, M

2004-07-01

While searching for prey, Molossus molossus broadcasts narrow-band calls of 11.42 ms organized in pairs of pulses that alternate in frequency. The first signal of the pair is at 34.5 kHz, the second at 39.6 kHz. Pairs of calls with changing frequencies were only emitted when the interpulse intervals were below 200 ms. Maximum duty cycles during search phase are close to 20%. Frequency alternation of search calls is interpreted as a mechanism for increasing duty cycle and thus the temporal continuity of scanning, as well as increasing the detection range. A neurophysiological correlate for the processing of search calls was found in the inferior colliculus. 64% of neurons respond to frequencies in the 30- to 40-kHz range and only in this frequency range were closed tuning curves found for levels below 40 dB SPL. In addition, 15% of the neurons have double-tuned frequency-threshold curves with best thresholds at 34 and 39 kHz. Differing from observations in other bats, approach calls of M. molossus are longer and of higher frequencies than search calls. Close to the roost, the call frequency is increased to 45.0-49.8 kHz and, in addition, extremely broadband signals are emitted. This demonstrates high plasticity of call design.

The synchronisation of lower limb responses with a variable metronome: the effect of biomechanical constraints on timing.

PubMed

Chen, Hui-Ya; Wing, Alan M; Pratt, David

2006-04-01

Stepping in time with a metronome has been reported to improve pathological gait. Although there have been many studies of finger tapping synchronisation tasks with a metronome, the specific details of the influences of metronome timing on walking remain unknown. As a preliminary to studying pathological control of gait timing, we designed an experiment with four synchronisation tasks, unilateral heel tapping in sitting, bilateral heel tapping in sitting, bilateral heel tapping in standing, and stepping on the spot, in order to examine the influence of biomechanical constraints on metronome timing. These four conditions allow study of the effects of bilateral co-ordination and maintenance of balance on timing. Eight neurologically normal participants made heel tapping and stepping responses in synchrony with a metronome producing 500 ms interpulse intervals. In each trial comprising 40 intervals, one interval, selected at random between intervals 15 and 30, was lengthened or shortened, which resulted in a shift in phase of all subsequent metronome pulses. Performance measures were the speed of compensation for the phase shift, in terms of the temporal difference between the response and the metronome pulse, i.e. asynchrony, and the standard deviation of the asynchronies and interresponse intervals of steady state synchronisation. The speed of compensation decreased with increase in the demands of maintaining balance. The standard deviation varied across conditions but was not related to the compensation speed. The implications of these findings for metronome assisted gait are discussed in terms of a first-order linear correction account of synchronisation.

Measuring sperm whales from their clicks: Stability of interpulse intervals and validation that they indicate whale length

NASA Astrophysics Data System (ADS)

Rhinelander, Marcus Q.; Dawson, Stephen M.

2004-04-01

Multiple pulses can often be distinguished in the clicks of sperm whales (Physeter macrocephalus). Norris and Harvey [in Animal Orientation and Navigation, NASA SP-262 (1972), pp. 397-417] proposed that this results from reflections within the head, and thus that interpulse interval (IPI) is an indicator of head length, and by extrapolation, total length. For this idea to hold, IPIs must be stable within individuals, but differ systematically among individuals of different size. IPI stability was examined in photographically identified individuals recorded repeatedly over different dives, days, and years. IPI variation among dives in a single day and days in a single year was statistically significant, although small in magnitude (it would change total length estimates by <3%). As expected, IPIs varied significantly among individuals. Most individuals showed significant increases in IPIs over several years, suggesting growth. Mean total lengths calculated from published IPI regressions were 13.1 to 16.1 m, longer than photogrammetric estimates of the same whales (12.3 to 15.3 m). These discrepancies probably arise from the paucity of large (12-16 m) whales in data used in published regressions. A new regression is offered for this size range.

Multimodal gain control at the hippocampal Schaffer collateral-CA1 synapse.

PubMed

Lange-Asschenfeldt, Christian; Schipke, Carola G; Riepe, Matthias W

2007-04-06

Information processing at central nervous system synapses is shaped by long-lasting modifications, such as long-term potentiation and short-lived and putatively synapse-specific modifications by various forms of short-term plasticity, such as facilitation, potentiation, and depression. Using an extracellular paired-pulse facilitation (PPF) protocol at the Schaffer collateral-CA1 (SC) connection in acute hippocampal slices in mice, we extend previous reports of optimal signal gain at intermediate interpulse intervals obtained at single SC synapses to the network level. Moreover, maximum signal gain changed when the input intensity was altered. We found further that facilitation decreased with increasing stimulus amplitude and duration in an exact exponential fashion when varied at a fixed interpulse interval. Variation of these intensity parameters accounted for significant changes in PPF adding a spatial dimension to time-based synaptic filter characteristics. Thus, this synapse functions as an amplitude window discriminator with a low-level aperture in combination with a band-pass frequency filter. By providing mathematical functions for the characteristic presynaptic parameters frequency, stimulus amplitude, and pulse duration at the network level our results lay ground for future studies on pharmacologically, genetically, or otherwise altered animal models.

Using a Double-Coil TMS Protocol to Assess Preparatory Inhibition Bilaterally.

PubMed

Vassiliadis, Pierre; Grandjean, Julien; Derosiere, Gerard; de Wilde, Ysaline; Quemener, Louise; Duque, Julie

2018-01-01

Transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1), elicits motor-evoked potentials (MEPs) in contralateral limb muscles which are valuable indicators of corticospinal excitability (CSE) at the time of stimulation. So far, most studies have used single-coil TMS over one M1, yielding MEPs in muscles of a single limb-usually the hand. However, tracking CSE in the two hands simultaneously would be useful in many contexts. We recently showed that, in the resting state, double-coil stimulation of the two M1 with a 1 ms inter-pulse interval (double-coil 1 ms TMS) elicits MEPs in both hands that are comparable to MEPs obtained using single-coil TMS. To further evaluate this new technique, we considered the MEPs elicited by double-coil 1 ms TMS in an instructed-delay choice reaction time task where a prepared response has to be withheld until an imperative signal is displayed. Single-coil TMS studies have repetitively shown that in this type of task, the motor system is transiently inhibited during the delay period, as evident from the broad suppression of MEP amplitudes. Here, we aimed at investigating whether a comparable inhibitory effect can be observed with MEPs elicited using double-coil 1 ms TMS. To do so, we compared the amplitude as well as the coefficient of variation (CV) of MEPs produced by double-coil 1 ms or single-coil TMS during action preparation. We observed that MEPs were suppressed (smaller amplitude) and often less variable (smaller CV) during the delay period compared to baseline. Importantly, these effects were equivalent whether single-coil or double-coil 1 ms TMS was used. This suggests that double-coil 1 ms TMS is a reliable tool to assess CSE, not only when subjects are at rest, but also when they are involved in a task, opening new research horizons for scientists interested in the corticospinal correlates of human behavior.

Using a Double-Coil TMS Protocol to Assess Preparatory Inhibition Bilaterally

PubMed Central

Vassiliadis, Pierre; Grandjean, Julien; Derosiere, Gerard; de Wilde, Ysaline; Quemener, Louise; Duque, Julie

2018-01-01

Transcranial magnetic stimulation (TMS) applied over the primary motor cortex (M1), elicits motor-evoked potentials (MEPs) in contralateral limb muscles which are valuable indicators of corticospinal excitability (CSE) at the time of stimulation. So far, most studies have used single-coil TMS over one M1, yielding MEPs in muscles of a single limb—usually the hand. However, tracking CSE in the two hands simultaneously would be useful in many contexts. We recently showed that, in the resting state, double-coil stimulation of the two M1 with a 1 ms inter-pulse interval (double-coil1 ms TMS) elicits MEPs in both hands that are comparable to MEPs obtained using single-coil TMS. To further evaluate this new technique, we considered the MEPs elicited by double-coil1 ms TMS in an instructed-delay choice reaction time task where a prepared response has to be withheld until an imperative signal is displayed. Single-coil TMS studies have repetitively shown that in this type of task, the motor system is transiently inhibited during the delay period, as evident from the broad suppression of MEP amplitudes. Here, we aimed at investigating whether a comparable inhibitory effect can be observed with MEPs elicited using double-coil1 ms TMS. To do so, we compared the amplitude as well as the coefficient of variation (CV) of MEPs produced by double-coil1 ms or single-coil TMS during action preparation. We observed that MEPs were suppressed (smaller amplitude) and often less variable (smaller CV) during the delay period compared to baseline. Importantly, these effects were equivalent whether single-coil or double-coil1 ms TMS was used. This suggests that double-coil1 ms TMS is a reliable tool to assess CSE, not only when subjects are at rest, but also when they are involved in a task, opening new research horizons for scientists interested in the corticospinal correlates of human behavior. PMID:29568258

Migration of cell surface concanavalin A receptors in pulsed electric fields.

PubMed Central

Lin-Liu, S; Adey, W R; Poo, M M

1984-01-01

Concanavalin A (con A) receptors on the surface of cultured Xenopus myoblasts redistributed in response to monopolar, pulsed electric fields. The prefield uniform distribution of the receptors became asymmetrical, and was polarized toward the cathodal pole, in the same way as in DC fields. The extent of asymmetry depended on the duration of field exposure, pulse width (or alternatively, interpulse interval), frequency, and intensity. This relationship was most conveniently expressed by using duty cycle, a quantity determined by both pulse width and frequency. Pulses of average intensity 1.5 V/cm induced detectable asymmetry within 5 min. At the lowest average field intensity used, 0.8 V/cm, significant asymmetry was detected at 150 min. For pulses of high duty cycle (greater than 25%), steady state was reached after 30 min exposure and the steady state asymmetry was dependent on average field intensity. For low duty cycle fields, the time required to reach steady state was prolonged (greater than 50 min). Before reaching a steady state, effectiveness of the pulses, as compared with DC fields of equivalent intensity, was a function of duty cycle. A low duty cycle field (fixed number of pulses at low frequency or long interpulse interval) was less effective than high duty cycle fields or DC. PMID:6743751

Methods of measurement signal acquisition from the rotational flow meter for frequency analysis

NASA Astrophysics Data System (ADS)

Świsulski, Dariusz; Hanus, Robert; Zych, Marcin; Petryka, Leszek

One of the simplest and commonly used instruments for measuring the flow of homogeneous substances is the rotational flow meter. The main part of such a device is a rotor (vane or screw) rotating at a speed which is the function of the fluid or gas flow rate. A pulse signal with a frequency proportional to the speed of the rotor is obtained at the sensor output. For measurements in dynamic conditions, a variable interval between pulses prohibits the analysis of the measuring signal. Therefore, the authors of the article developed a method involving the determination of measured values on the basis of the last inter-pulse interval preceding the moment designated by the timing generator. For larger changes of the measured value at a predetermined time, the value can be determined by means of extrapolation of the two adjacent interpulse ranges, assuming a linear change in the flow. The proposed methods allow analysis which requires constant spacing between measurements, allowing for an analysis of the dynamics of changes in the test flow, eg. using a Fourier transform. To present the advantages of these methods simulations of flow measurement were carried out with a DRH-1140 rotor flow meter from the company Kobold.

Chaotic carrier pulse position modulation communication system and method

DOEpatents

Abarbanel, Henry D. I.; Larson, Lawrence E.; Rulkov, Nikolai F.; Sushchik, Mikhail M.; Tsimring, Lev S.; Volkovskii, Alexander R.

2001-01-01

A chaotic carrier pulse position modulation communication system and method is disclosed. The system includes a transmitter and receiver having matched chaotic pulse regenerators. The chaotic pulse regenerator in the receiver produces a synchronized replica of a chaotic pulse train generated by the regenerator in the transmitter. The pulse train from the transmitter can therefore act as a carrier signal. Data is encoded by the transmitter through selectively altering the interpulse timing between pulses in the chaotic pulse train. The altered pulse train is transmitted as a pulse signal. The receiver can detect whether a particular interpulse interval in the pulse signal has been altered by reference to the synchronized replica it generates, and can therefore detect the data transmitted by the receiver. Preferably, the receiver predicts the earliest moment in time it can expect a next pulse after observation of at least two consecutive pulses. It then decodes the pulse signal beginning at a short time before expected arrival of a pulse.

Reflection of the State of Hunger in Impulse Activity of Nose Wing Muscles and Upper Esophageal Sphincter during Search behavior in Rabbits.

PubMed

Kromin, A A; Dvoenko, E E; Zenina, O Yu

2016-07-01

Reflection of the state of hunger in impulse activity of nose wing muscles and upper esophageal sphincter muscles was studied in chronic experiments on rabbits subjected to 24-h food deprivation in the absence of locomotion and during search behavior. In the absence of apparent behavioral activity, including sniffing, alai nasi muscles of hungry rabbits constantly generated bursts of action potentials synchronous with breathing, while upper esophageal sphincter muscles exhibited regular aperiodic low-amplitude impulse activity of tonic type. Latent form of food motivation was reflected in the structure of temporal organization of impulse activity of alai nasi muscles in the form of bimodal distribution of interpulse intervals and in temporal structure of impulse activity of upper esophageal sphincter muscles in the form of monomodal distribution. The latent form of food motivation was manifested in the structure of temporal organization of periods of the action potentials burst-like rhythm, generated by alai nasi muscles, in the form of monomodal distribution, characterized by a high degree of dispersion of respiratory cycle periods. In the absence of physical activity hungry animals sporadically exhibited sniffing activity, manifested in the change from the burst-like impulse activity of alai nasi muscles to the single-burst activity type with bimodal distribution of interpulse intervals and monomodal distribution of the burst-like action potentials rhythm periods, the maximum of which was shifted towards lower values, which was the cause of increased respiratory rate. At the same time, the monomodal temporal structure of impulse activity of the upper esophageal sphincter muscles was not changed. With increasing food motivation in the process of search behavior temporal structure of periods of the burst-like action potentials rhythm, generated by alai nasi muscles, became similar to that observed during sniffing, not accompanied by animal's locomotion, which is typical for the increased respiratory rhythm frequency. Increased hunger motivation was reflected in the temporal structure of impulse activity of upper esophageal sphincter muscles in the form of a shift to lower values of the maximum of monomodal distribution of interpulse intervals on the histogram, resulting in higher impulse activity frequency. The simultaneous increase in the frequency of action potentials bursts generation by alai nasi muscles and regular impulse activity of upper esophageal sphincter muscles is a reliable criterion for enhanced food motivation during search behavior in rabbits.

Search for a Correlation Between Very-High-Energy Gamma Rays and Giant Radio Pulses in the Crab Pulsar

NASA Technical Reports Server (NTRS)

Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Bouvier, A.; Buckley, J. H.; Bugaev, V.; Byrum, K.;

Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013

PubMed Central

Weirathmueller, Michelle J.; Stafford, Kathleen M.; Wilcock, William S. D.; Hilmo, Rose S.; Dziak, Robert P.; Tréhu, Anne M.

2017-01-01

In order to study the long-term stability of fin whale (Balaenoptera physalus) singing behavior, the frequency and inter-pulse interval of fin whale 20 Hz vocalizations were observed over 10 years from 2003–2013 from bottom mounted hydrophones and seismometers in the northeast Pacific Ocean. The instrument locations extended from 40°N to 48°N and 130°W to 125°W with water depths ranging from 1500–4000 m. The inter-pulse interval (IPI) of fin whale song sequences was observed to increase at a rate of 0.54 seconds/year over the decade of observation. During the same time period, peak frequency decreased at a rate of 0.17 Hz/year. Two primary call patterns were observed. During the earlier years, the more commonly observed pattern had a single frequency and single IPI. In later years, a doublet pattern emerged, with two dominant frequencies and IPIs. Many call sequences in the intervening years appeared to represent a transitional state between the two patterns. The overall trend was consistent across the entire geographical span, although some regional differences exist. Understanding changes in acoustic behavior over long time periods is needed to help establish whether acoustic characteristics can be used to help determine population identity in a widely distributed, difficult to study species such as the fin whale. PMID:29073230

Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013.

PubMed

Weirathmueller, Michelle J; Stafford, Kathleen M; Wilcock, William S D; Hilmo, Rose S; Dziak, Robert P; Tréhu, Anne M

2017-01-01

In order to study the long-term stability of fin whale (Balaenoptera physalus) singing behavior, the frequency and inter-pulse interval of fin whale 20 Hz vocalizations were observed over 10 years from 2003-2013 from bottom mounted hydrophones and seismometers in the northeast Pacific Ocean. The instrument locations extended from 40°N to 48°N and 130°W to 125°W with water depths ranging from 1500-4000 m. The inter-pulse interval (IPI) of fin whale song sequences was observed to increase at a rate of 0.54 seconds/year over the decade of observation. During the same time period, peak frequency decreased at a rate of 0.17 Hz/year. Two primary call patterns were observed. During the earlier years, the more commonly observed pattern had a single frequency and single IPI. In later years, a doublet pattern emerged, with two dominant frequencies and IPIs. Many call sequences in the intervening years appeared to represent a transitional state between the two patterns. The overall trend was consistent across the entire geographical span, although some regional differences exist. Understanding changes in acoustic behavior over long time periods is needed to help establish whether acoustic characteristics can be used to help determine population identity in a widely distributed, difficult to study species such as the fin whale.

Pulse stuttering as a remedy for aliased ground backscatter

NASA Astrophysics Data System (ADS)

Bowhill, S. A.

1983-12-01

An algorithm that aides in the removal of ground scatter from low frequency Mesosphere, Stratosphere, Troposphere (MST) radar signals is examined. The unwanted ground scatter is shown as a sequence of velocity plots which are almost typical at the various altitudes. The interpulse period is changed in a cyclic way, thereby destroying the coherence of the unwanted signal. The interpulse period must be changed by an amount at least equal to the transmitted pulse width, and optimum performance is obtained when the number of different interpulse period occupies a time span greater than the coherence time of the unwanted signal. Since a 20-msec pulse width is used, it was found convenient to cycle through 50 pulses, the interpulse period changing from 2 msec to 3 msec during the 1/8-second time. This particular pattern of interpulse periods was provided by a software radar controller. With application of this algorithm, the unwanted scatter signal becomes incoherent from one pulse to the next, and therefore is perceived as noise by the coherent integrator and correlator.

Pulse stuttering as a remedy for aliased ground backscatter

NASA Technical Reports Server (NTRS)

Bowhill, S. A.

1983-01-01

An algorithm that aides in the removal of ground scatter from low frequency Mesosphere, Stratosphere, Troposphere (MST) radar signals is examined. The unwanted ground scatter is shown as a sequence of velocity plots which are almost typical at the various altitudes. The interpulse period is changed in a cyclic way, thereby destroying the coherence of the unwanted signal. The interpulse period must be changed by an amount at least equal to the transmitted pulse width, and optimum performance is obtained when the number of different interpulse period occupies a time span greater than the coherence time of the unwanted signal. Since a 20-msec pulse width is used, it was found convenient to cycle through 50 pulses, the interpulse period changing from 2 msec to 3 msec during the 1/8-second time. This particular pattern of interpulse periods was provided by a software radar controller. With application of this algorithm, the unwanted scatter signal becomes incoherent from one pulse to the next, and therefore is perceived as noise by the coherent integrator and correlator.

Annotated Bibliography of Publications from the U.S. Navy’s Marine Mammal Program.

DTIC Science & Technology

1987-11-01

1984 Dolphin biosonar detection in clutter: Variation in the payoff matrix. Jour. Acoust. Soc. Am. 76(3):955-957. A bottlenose dolphin was trained to...Tursiops biosonar detection in noise. In: Animal Sonar Systems, pp. 957-959 (ed. R.-G. Busnel and J. F. Fish), Plenum Press. In a detection problem in a...82 and 87 dB, the click trains became shorter and latencies were longer. Penner. R. H., and J. Kadane 1980 Biosonar interpulse interval as an

[Echolocation calls of free-flying Himalayan swiftlets (Aerodramus brevirostris)].

PubMed

Wang, Bin; Ma, Jian-Zhang; Chen, Yi; Tan, Liang-Jing; Liu, Qi; Shen, Qi-Qi; Liao, Qing-Yi; Zhang, Li-Biao

2013-02-01

Here, we present our findings of free-flying echolocation calls of Himalayan swiftlets (Aerodramus brevirostris), which were recorded in Shenjing Cave, Hupingshan National Reserve, Shimen County, Hunan Province in June 2012, using Avisoft-UltraSoundGate 116(e). We noted that after foraging at dusk, the Himalayan swiftlets flew fast into the cave without clicks, and then slowed down in dark area in the cave, but with sounds. The echolocation sounds of Himalayan swiftlets are broadband, double noise burst clicks, separated by a short pause. The inter-pulse intervals between double clicks (99.3±3.86 ms)were longer than those within double clicks (6.6±0.42 ms) (P<0.01). With the exception of peak frequency, between 6.2±0.08 kHz and 6.2±0.10 kHz, (P>0.05) and pulse duration 2.9±0.12 ms, 3.2±0.17 ms, (P>0.05) between the first and second, other factors-maximum frequency, minimum frequency, frequency bandwidth, and power-were significantly different between the clicks. The maximum frequency of the first pulse (20.1±1.10 kHz) was higher than that of second (15.4±0.98 kHz) (P<0.01), while the minimum frequency of the first pulse (3.7±0.12 kHz) was lower than that of second (4.0±0.09 kHz) (P<0.05); resulting in the frequency bandwidth of the first pulse (16.5±1.17 kHz) longer than that of second (11.4±1.01 kHz) (P<0.01). The power of the first pulse (-32.5±0.60 dB) was higher than that of second (-35.2±0.94 dB) (P<0.05). More importantly, we found that Himalayan swiftlets emitted echolocation pulses including ultrasonic sound, with a maximum frequency reaching 33.2 kHz.

Double-pulse femtosecond laser peening of aluminum alloy AA5038: Effect of inter-pulse delay on transient optical plume emission and final surface micro-hardness

NASA Astrophysics Data System (ADS)

Ageev, E. I.; Bychenkov, V. Yu.; Ionin, A. A.; Kudryashov, S. I.; Petrov, A. A.; Samokhvalov, A. A.; Veiko, V. P.

2016-11-01

Double-pulse ablative femtosecond laser peening of the AA5038 aluminum alloy surface in the phase explosion regime results in its enhanced microhardness, which monotonously decreases till the initial value versus inter-pulse delay, increasing on a sub-nanosecond timescale. Optical emission spectroscopy of the double-pulse ablative plume reveals the same trend in the yield of the corresponding atomic and ion emission versus inter-pulse delay, enlightening the interaction of the second femtosecond laser pump pulse with the surface and the resulting plume.

PHYSICAL FUNDAMENTALS OF QUANTUM ELECTRONICS: Interaction of a sequence of short broad-band radiation pulses with a diatomic molecule

NASA Astrophysics Data System (ADS)

Oraevsky, Anatolii N.; Kozlovskii, Andrei V.; Chichkov, B. N.

1998-07-01

A theoretical analysis is made of the process in which a molecule undergoes a transition between the ground and excited electronic states under the action of a radiation pulse and then, in the interpulse interval, returns to the ground electronic state. Such a periodic process is important in the cooling of molecules by laser radiation. It is shown that the radiation parameters can be selected so that the CO and CN molecules experience over 1000 excitation—relaxation events without dissociation.

Echo tracker/range finder for radars and sonars

NASA Technical Reports Server (NTRS)

Constantinides, N. J. (Inventor)

1982-01-01

An echo tracker/range finder or altimeter is described. The pulse repetition frequency (PFR) of a predetermined plurality of transmitted pulses is adjusted so that echo pulses received from a reflecting object are positioned between transmitted pulses and divided their interpulse time interval into two time intervals having a predetermined ratio with respect to each other. The invention described provides a means whereby the arrival time of a plurality of echo pulses is defined as the time at which a composite echo pulse formed of a sum of the individual echo pulses has the highest amplitude. The invention is applicable to radar systems, sonar systems, or any other kind of system in which pulses are transmitted and echoes received therefrom.

Pulsed welding plasma source

NASA Astrophysics Data System (ADS)

Knyaz'kov, A.; Pustovykh, O.; Verevkin, A.; Terekhin, V.; Shachek, A.; Tyasto, A.

2016-04-01

It is shown that in order to form the current pulse of a near rectangular shape, which provides conversion of the welding arc into a dynamic mode, it is rational to connect a forming element made on the basis of an artificial forming line in series to the welding DC circuit. The paper presents a diagram of a pulsed device for welding with a non-consumable electrode in argon which was developed using the forming element. The conversion of the arc into the dynamic mode is illustrated by the current and voltage oscillograms of the arc gap and the dynamic characteristic of the arc within the interval of one pulse generation time in the arc gap. The background current travels in the interpulse interval.

Biphasic pulses enhance bleomycin efficacy in a spontaneous canine genital tumor model of chemoresistance: Sticker sarcoma

PubMed Central

Spugnini , Enrico P; Dotsinsky , Ivan; Mudrov , Nikolay; Citro , Gennaro; D'Avino , Alfredo; Baldi , Alfonso

2008-01-01

Sticker's sarcoma (also known as transmissible venereal tumor) is a horizontally transmitted neoplasm of the dog, that is passed with coitus. It is a locally aggressive tumor with a low tendency to metastatic spread. The most common locations are the genitals, the nose, the perianal area. Standard treatment consists with chemotherapy with vincristine, however other therapies such as, cryotherapy, immunotherapy or, in selected cases, radiation therapy, have been reported. In this article we describe the outcome of a small cohort of canine patients, with chemotherapy resistant transmissible venereal tumor (TVT), treated with bleomycin selectively driven by trains of biphasic pulses (electrochemotherapy). Three canine patients, with refractory TVT, entered the study and received two sessions of ECT under sedation. The pets had local injection of bleomycin at the concentration of 1.5 mg/ml and five minutes after the chemotherapy, trains of 8 biphasic electric pulses lasting 50 + 50 μs each, with 1 ms interpulse intervals, were delivered by means of modified caliper or, for difficult districts, through paired needle electrode. All the patients responded to the treatment and are still in remission at different times. Electrochemotherapy appears as a safe and efficacious modality for the treatment of TVT and warrants further investigations. PMID:18980687

Discrimination between sequential and simultaneous virtual channels with electrical hearing

PubMed Central

Landsberger, David; Galvin, John J.

2011-01-01

In cochlear implants (CIs), simultaneous or sequential stimulation of adjacent electrodes can produce intermediate pitch percepts between those of the component electrodes. However, it is unclear whether simultaneous and sequential virtual channels (VCs) can be discriminated. In this study, CI users were asked to discriminate simultaneous and sequential VCs; discrimination was measured for monopolar (MP) and bipolar + 1 stimulation (BP + 1), i.e., relatively broad and focused stimulation modes. For sequential VCs, the interpulse interval (IPI) varied between 0.0 and 1.8 ms. All stimuli were presented at comfortably loud, loudness-balanced levels at a 250 pulse per second per electrode (ppse) stimulation rate. On average, CI subjects were able to reliably discriminate between sequential and simultaneous VCs. While there was no significant effect of IPI or stimulation mode on VC discrimination, some subjects exhibited better VC discrimination with BP + 1 stimulation. Subjects’ discrimination between sequential and simultaneous VCs was correlated with electrode discrimination, suggesting that spatial selectivity may influence perception of sequential VCs. To maintain equal loudness, sequential VC amplitudes were nearly double those of simultaneous VCs, presumably resulting in a broader spread of excitation. These results suggest that perceptual differences between simultaneous and sequential VCs might be explained by differences in the spread of excitation. PMID:21895094

Discrimination between sequential and simultaneous virtual channels with electrical hearing.

PubMed

Landsberger, David; Galvin, John J

2011-09-01

In cochlear implants (CIs), simultaneous or sequential stimulation of adjacent electrodes can produce intermediate pitch percepts between those of the component electrodes. However, it is unclear whether simultaneous and sequential virtual channels (VCs) can be discriminated. In this study, CI users were asked to discriminate simultaneous and sequential VCs; discrimination was measured for monopolar (MP) and bipolar + 1 stimulation (BP + 1), i.e., relatively broad and focused stimulation modes. For sequential VCs, the interpulse interval (IPI) varied between 0.0 and 1.8 ms. All stimuli were presented at comfortably loud, loudness-balanced levels at a 250 pulse per second per electrode (ppse) stimulation rate. On average, CI subjects were able to reliably discriminate between sequential and simultaneous VCs. While there was no significant effect of IPI or stimulation mode on VC discrimination, some subjects exhibited better VC discrimination with BP + 1 stimulation. Subjects' discrimination between sequential and simultaneous VCs was correlated with electrode discrimination, suggesting that spatial selectivity may influence perception of sequential VCs. To maintain equal loudness, sequential VC amplitudes were nearly double those of simultaneous VCs, presumably resulting in a broader spread of excitation. These results suggest that perceptual differences between simultaneous and sequential VCs might be explained by differences in the spread of excitation. © 2011 Acoustical Society of America

Effect of ageing on the force development in tetanic contractions of motor units in rat medial gastrocnemius muscle.

PubMed

Łochyński, Dawid; Kaczmarek, Dominik; Krutki, Piotr; Celichowski, Jan

2010-09-01

The purpose of this study was to determine the effect of ageing on the rate of force generation of motor units, and the mechanical efficiency of contraction produced by a doublet discharge. The study was carried out on isolated motor units of rat medial gastrocnemius muscle of young (5-10 mo) and two groups of old (24-25 and 28-30 mo) Wistar rats. Motor units were classified into the fast fatigable (FF), fast resistant (FR) and slow (S) ones. The force output and rate of force development were determined for non-doublet unfused tetanic contractions evoked by a series of a constant-rate trains of pulses and corresponding doublet contractions starting with an initial brief interpulse interval of 5 ms, and for maximal tetanic contraction. In FF motor units the rate of force development and the force produced by the doublet discharge increased transiently at the age of 24-25 mo, while in S and FR motor units this increase was observed at the age of 28-30 mo. Age-related decrease in the rate of force development of skeletal muscle cannot be attributed to a decline in efficiency of force production by functioning motor units. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

GABAergic Local Interneurons Shape Female Fruit Fly Response to Mating Songs.

PubMed

Yamada, Daichi; Ishimoto, Hiroshi; Li, Xiaodong; Kohashi, Tsunehiko; Ishikawa, Yuki; Kamikouchi, Azusa

2018-05-02

Many animals use acoustic signals to attract a potential mating partner. In fruit flies ( Drosophila melanogaster ), the courtship pulse song has a species-specific interpulse interval (IPI) that activates mating. Although a series of auditory neurons in the fly brain exhibit different tuning patterns to IPIs, it is unclear how the response of each neuron is tuned. Here, we studied the neural circuitry regulating the activity of antennal mechanosensory and motor center (AMMC)-B1 neurons, key secondary auditory neurons in the excitatory neural pathway that relay song information. By performing Ca 2+ imaging in female flies, we found that the IPI selectivity observed in AMMC-B1 neurons differs from that of upstream auditory sensory neurons [Johnston's organ (JO)-B]. Selective knock-down of a GABA A receptor subunit in AMMC-B1 neurons increased their response to short IPIs, suggesting that GABA suppresses AMMC-B1 activity at these IPIs. Connection mapping identified two GABAergic local interneurons that synapse with AMMC-B1 and JO-B. Ca 2+ imaging combined with neuronal silencing revealed that these local interneurons, AMMC-LN and AMMC-B2, shape the response pattern of AMMC-B1 neurons at a 15 ms IPI. Neuronal silencing studies further suggested that both GABAergic local interneurons suppress the behavioral response to artificial pulse songs in flies, particularly those with a 15 ms IPI. Altogether, we identified a circuit containing two GABAergic local interneurons that affects the temporal tuning of AMMC-B1 neurons in the song relay pathway and the behavioral response to the courtship song. Our findings suggest that feedforward inhibitory pathways adjust the behavioral response to courtship pulse songs in female flies. SIGNIFICANCE STATEMENT To understand how the brain detects time intervals between sound elements, we studied the neural pathway that relays species-specific courtship song information in female Drosophila melanogaster We demonstrate that the signal transmission from auditory sensory neurons to key secondary auditory neurons antennal mechanosensory and motor center (AMMC)-B1 is the first-step to generate time interval selectivity of neurons in the song relay pathway. Two GABAergic local interneurons are suggested to shape the interval selectivity of AMMC-B1 neurons by receiving auditory inputs and in turn providing feedforward inhibition onto AMMC-B1 neurons. Furthermore, these GABAergic local interneurons suppress the song response behavior in an interval-dependent manner. Our results provide new insights into the neural circuit basis to adjust neuronal and behavioral responses to a species-specific communication sound. Copyright © 2018 the authors 0270-6474/18/384329-19$15.00/0.

A biologically inspired model of bat echolocation in a cluttered environment with inputs designed from field Recordings

NASA Astrophysics Data System (ADS)

Loncich, Kristen Teczar

Bat echolocation strategies and neural processing of acoustic information, with a focus on cluttered environments, is investigated in this study. How a bat processes the dense field of echoes received while navigating and foraging in the dark is not well understood. While several models have been developed to describe the mechanisms behind bat echolocation, most are based in mathematics rather than biology, and focus on either peripheral or neural processing---not exploring how these two levels of processing are vitally connected. Current echolocation models also do not use habitat specific acoustic input, or account for field observations of echolocation strategies. Here, a new approach to echolocation modeling is described capturing the full picture of echolocation from signal generation to a neural picture of the acoustic scene. A biologically inspired echolocation model is developed using field research measurements of the interpulse interval timing used by a frequency modulating (FM) bat in the wild, with a whole method approach to modeling echolocation including habitat specific acoustic inputs, a biologically accurate peripheral model of sound processing by the outer, middle, and inner ear, and finally a neural model incorporating established auditory pathways and neuron types with echolocation adaptations. Field recordings analyzed underscore bat sonar design differences observed in the laboratory and wild, and suggest a correlation between interpulse interval groupings and increased clutter. The scenario model provides habitat and behavior specific echoes and is a useful tool for both modeling and behavioral studies, and the peripheral and neural model show that spike-time information and echolocation specific neuron types can produce target localization in the midbrain.

Minimizing photodecomposition of flavin adenine dinucleotide fluorescence by the use of pulsed LEDs.

PubMed

Rösner, J; Liotta, A; Angamo, E A; Spies, C; Heinemann, U; Kovács, R

2016-11-01

Dynamic alterations in flavin adenine dinucleotide (FAD) fluorescence permit insight into energy metabolism-dependent changes of intramitochondrial redox potential. Monitoring FAD fluorescence in living tissue is impeded by photobleaching, restricting the length of microfluorimetric recordings. In addition, photodecomposition of these essential electron carriers negatively interferes with energy metabolism and viability of the biological specimen. Taking advantage of pulsed LED illumination, here we determined the optimal excitation settings giving the largest fluorescence yield with the lowest photobleaching and interference with metabolism in hippocampal brain slices. The effects of FAD bleaching on energy metabolism and viability were studied by monitoring tissue pO 2 , field potentials and changes in extracellular potassium concentration ([K + ] o ). Photobleaching with continuous illumination consisted of an initial exponential decrease followed by a nearly linear decay. The exponential decay was significantly decelerated with pulsed illumination. Pulse length of 5 ms was sufficient to reach a fluorescence output comparable to continuous illumination, whereas further increasing duration increased photobleaching. Similarly, photobleaching increased with shortening of the interpulse interval. Photobleaching was partially reversible indicating the existence of a transient nonfluorescent flavin derivative. Pulsed illumination decreased FAD photodecomposition, improved slice viability and reproducibility of stimulus-induced FAD, field potential, [K + ] o and pO 2 changes as compared to continuous illumination. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Pulsations, interpulsations, and sea-floor spreading.

NASA Technical Reports Server (NTRS)

Pessagno, E. A., Jr.

1973-01-01

It is postulated that worldwide transgressions (pulsations) and regressions (interpulsations) through the course of geologic time are related to the elevation and subsidence of oceanic ridge systems and to sea-floor spreading. Two multiple working hypotheses are advanced to explain major transgressions and regressions and the elevation and subsidence of oceanic ridge systems. One hypothesis interrelates the sea-floor spreading hypothesis to the hypothesis of sub-Mohorovicic serpentinization. The second hypothesis relates the sea-floor spreading hypothesis to a hypothesis involving thermal expansion and contraction.

Hemiparetic stepping to the beat: asymmetric response to metronome phase shift during treadmill gait.

PubMed

Pelton, Trudy A; Johannsen, Leif; Huiya Chen; Wing, Alan M

2010-06-01

Walking in time with a metronome is associated with improved spatiotemporal parameters in hemiparetic gait; however, the mechanism linking auditory and motor systems is poorly understood. Hemiparetic cadence control with metronome synchronization was examined to determine specific influences of metronome timing on treadmill walking. A within-participant experiment examined correction processes used to maintain heel strike synchrony with the beat by applying perturbations to the timing of a metronome. Eight chronic hemiparetic participants (mean age = 70 years; standard deviation = 12) were required to synchronize heel strikes with metronome pulses set according to each individual's comfortable speed (mean 0.4 m/s). During five 100-pulse trials, a fixed-phase baseline was followed by 4 unpredictable metronome phase shifts (20% of the interpulse interval), which amounted to 10 phase shifts on each foot. Infrared cameras recorded the motion of bilateral heel markers at 120 Hz. Relative asynchrony between heel strike responses and metronome pulses was used to index compensation for metronome phase shifts. Participants demonstrated compensation for phase shifts with convergence back to pre-phase shift asynchrony. This was significantly slower when the error occurred on the nonparetic side (requiring initial correction with the paretic limb) compared with when the error occurred on the paretic side (requiring initial nonparetic correction). Although phase correction of gait is slowed when the phase shift is delivered to the nonparetic side compared with the paretic side, phase correction is still present. This may underlie the utility of rhythmic auditory cueing in hemiparetic gait rehabilitation.

Optimal parameters of transcorneal electrical stimulation (TES) to be neuroprotective of axotomized RGCs in adult rats.

PubMed

Morimoto, Takeshi; Miyoshi, Tomomitsu; Sawai, Hajime; Fujikado, Takashi

2010-02-01

We previously showed that transcorneal electrical stimulation (TES) promoted the survival of axotomized retinal ganglion cells (RGCs) of rats. However the relationship between the parameters of TES and the neuroprotective effect of TES on axotomized RGCs was unclear. In the present study, we determined whether the neuroprotective effect of TES is affected by the parameters of TES. Adult male Wistar rats received TES just after transection of the left optic nerve (ON). The pulse duration, current intensity, frequency, waveform, and numbers of sessions of the TES were changed systematically. The alterations of the retina were examined histologically seven days or fourteen days after the ON transection. The optimal neuroprotective parameters were pulse duration of 1 and 2 ms/phase (P < 0.001, each), current intensity of 100 and 200 muA (P < 0.05, each), and stimulation frequency of 1, 5, and 20 Hz (P < 0.001, respectively). More than 30 min of TES was necessary to have a neuroprotective effect (P < 0.001). Symmetric pulses without an inter-pulse interval were most effective (P < 0.001). Repeated TES was more neuroprotective than a single TES at 14 days after ON transection (P < 0.001). Our results indicate that there is a range of optimal neuroprotective parameters of TES for axotomized RGCs of rats. These values will provide a guideline for the use of TES in patients with different retinal and optic nerve diseases. Copyright 2009 Elsevier Ltd. All rights reserved.

Cocaine effects on pulsatile secretion of anterior pituitary, gonadal, and adrenal hormones.

PubMed

Mendelson, J H; Mello, N K; Teoh, S K; Ellingboe, J; Cochin, J

1989-12-01

Pulse frequency analysis of LH, PRL, testosterone, and cortisol was carried out with the Cluster Analysis Program in eight male cocaine abusers and eight aged-matched normal men. Four of the eight cocaine abusers had hyperprolactinemia (range, 22.08-44.65 micrograms/L). Cocaine users as a group had significantly higher mean peak height (P less than 0.02) than control subjects. Cocaine users with hyperprolactinemia had higher mean peak height than control subjects or cocaine users with normal PRL levels (P less than 0.01). Cocaine users with hyperprolactinemia also had higher mean amplitude increments than control subjects (P less than 0.02). Cocaine users with hyperprolactinemia had a higher mean valley than controls (P less than 0.01) and cocaine users with normal PRL levels (P less than 0.03). However, there were no significant differences in PRL peak frequency, peak duration, or interpulse intervals between cocaine users with or without hyperprolactinemia and control subjects. There were minimal differences between cocaine users and control subjects in pulse frequency analysis of LH parameters; the small differences in mean LH levels and average interpulse interval were not in the abnormal range and were probably not biologically significant. No differences between cocaine users and controls were detected for pulse frequency analysis of testosterone or cortisol. Cocaine-induced hyperprolactinemia may contribute to disorders of sexual and reproductive function in men who abuse the drug, and recent reports that PRL modulates immune function suggest that cocaine-induced derangements of PRL secretion may also contribute to cocaine-related comorbidity in infectious disease. Since cocaine users with hyperprolactinemia had a higher mean valley as well as a higher peak pulse PRL height than control subjects, but did not have greater PRL pulse frequencies, we conclude that hyperprolactinemia in these men may be due to a cocaine-induced derangement of dopaminergic inhibition of basal PRL secretion.

THE CRAB PULSAR AT CENTIMETER WAVELENGTHS. II. SINGLE PULSES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hankins, T. H.; Eilek, J. A.; Jones, G., E-mail: thankins@aoc.nrao.edu

2016-12-10

We have carried out new, high-frequency, high-time-resolution observations of the Crab pulsar. Combining these with our previous data, we characterize bright single pulses associated with the Main Pulse, both the Low-Frequency and High-Frequency Interpulses, and the two  High-Frequency Components. Our data include observations at frequencies ranging from 1 to 43 GHz with time resolutions down to a fraction of a nanosecond. We find that at least two types of emission physics are operating in this pulsar. Both Main Pulses and Low-Frequency Interpulses, up to ∼10 GHz, are characterized by nanoshot emission—overlapping clumps of narrowband nanoshots, each with its own polarization signature.more » High-Frequency Interpulses, between 5 and 30 GHz, are characterized by spectral band emission—linearly polarized emission containing ∼30 proportionately spaced spectral bands. We cannot say whether the longer-duration High-Frequency Components pulses are due to a scattering process, or if they come from yet another type of emission physics.« less

Hitomi X-ray studies of giant radio pulses from the Crab pulsar

NASA Astrophysics Data System (ADS)

Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier O.; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Oshimizu, Kenya; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shiníchiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shiníchiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Terasawa, Toshio; Sekido, Mamoru; Takefuji, Kazuhiro; Kawai, Eiji; Misawa, Hiroaki; Tsuchiya, Fuminori; Yamazaki, Ryo; Kobayashi, Eiji; Kisaka, Shota; Aoki, Takahiro

2018-03-01

To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 σ fluctuations of the X-ray fluxes at the pulse peaks, and the 3 σ upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2-300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and 70-300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) × 10-11 erg cm-2, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a >0.02% brightening of the pulse-peak flux under such conditions.

Self-pulsations and excitability in optically injected quantum-dot lasers: Impact of the excited states and spontaneous emission noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olejniczak, Lukasz; SUPELEC, OPTEL, and LMOPS EA 4423; Panajotov, Krassimir

2010-08-15

We study the dynamics of an optically injected quantum-dot laser accounting for excited states. Mapping of the bifurcations in the plane frequency detuning vs. injection strength shows that the relaxation rate scales the regions of locking and single- and double-period solutions, while the capture rate has a minor effect. Within the regions of time-periodic solutions, close to the saddle-node bifurcation boundary, we identify subregions where the output signal resembles excitable pulses as a result of the bottleneck phenomenon. We show that such emission is determined mainly by fluctuations in the occupation of the excited states. The interpulse time follows anmore » inverse square root scaling law as a function of the detuning. In a deterministic system the pulses are periodic regardless of the detuning, but in the presence of noise, close to the locking region, the interpulse time follows a positively skewed normal distribution. For a fixed frequency detuning, increasing the noise strength can shift the mean of the interpulse time distribution and make the pulsations more periodic.« less

Characterizing the graded structure of false killer whale (Pseudorca crassidens) vocalizations.

PubMed

Murray, S O; Mercado, E; Roitblat, H L

1998-09-01

The vocalizations from two, captive false killer whales (Pseudorca crassidens) were analyzed. The structure of the vocalizations was best modeled as lying along a continuum with trains of discrete, exponentially damped sinusoidal pulses at one end and continuous sinusoidal signals at the other end. Pulse trains were graded as a function of the interval between pulses where the minimum interval between pulses could be zero milliseconds. The transition from a pulse train with no inter-pulse interval to a whistle could be modeled by gradations in the degree of damping. There were many examples of vocalizations that were gradually modulated from pulse trains to whistles. There were also vocalizations that showed rapid shifts in signal type--for example, switching immediately from a whistle to a pulse train. These data have implications when considering both the possible function(s) of the vocalizations and the potential sound production mechanism(s). A short-time duty cycle measure was developed to characterize the graded structure of the vocalizations. A random sample of 500 vocalizations was characterized by combining the duty cycle measure with peak frequency measurements. The analysis method proved to be an effective metric for describing the graded structure of false killer whale vocalizations.

Song pattern recognition in crickets based on a delay-line and coincidence-detector mechanism

PubMed Central

Sarmiento-Ponce, Edith Julieta

2017-01-01

Acoustic communication requires filter mechanisms to process and recognize key features of the perceived signals. We analysed such a filter mechanism in field crickets (Gryllus bimaculatus), which communicate with species-specific repetitive patterns of sound pulses and chirps. A delay-line and coincidence-detection mechanism, in which each sound pulse has an impact on the processing of the following pulse, is implicated to underlie the recognition of the species-specific pulse pattern. Based on this concept, we hypothesized that altering the duration of a single pulse or inter-pulse interval in three-pulse chirps will lead to different behavioural responses. Phonotaxis was tested in female crickets walking on a trackball exposed to different sound paradigms. Changing the duration of either the first, second or third pulse of the chirps led to three different characteristic tuning curves. Long first pulses decreased the phonotactic response whereas phonotaxis remained strong when the third pulse was long. Chirps with three pulses of increasing duration of 5, 20 and 50 ms elicited phonotaxis, but the chirps were not attractive when played in reverse order. This demonstrates specific, pulse duration-dependent effects while sequences of pulses are processed. The data are in agreement with a mechanism in which processing of a sound pulse has an effect on the processing of the subsequent pulse, as outlined in the flow of activity in a delay-line and coincidence-detector circuit. Additionally our data reveal a substantial increase in the gain of phonotaxis, when the number of pulses of a chirp is increased from two to three. PMID:28539524

Song pattern recognition in crickets based on a delay-line and coincidence-detector mechanism.

PubMed

Hedwig, Berthold; Sarmiento-Ponce, Edith Julieta

2017-05-31

Acoustic communication requires filter mechanisms to process and recognize key features of the perceived signals. We analysed such a filter mechanism in field crickets ( Gryllus bimaculatus ), which communicate with species-specific repetitive patterns of sound pulses and chirps. A delay-line and coincidence-detection mechanism, in which each sound pulse has an impact on the processing of the following pulse, is implicated to underlie the recognition of the species-specific pulse pattern. Based on this concept, we hypothesized that altering the duration of a single pulse or inter-pulse interval in three-pulse chirps will lead to different behavioural responses. Phonotaxis was tested in female crickets walking on a trackball exposed to different sound paradigms. Changing the duration of either the first, second or third pulse of the chirps led to three different characteristic tuning curves. Long first pulses decreased the phonotactic response whereas phonotaxis remained strong when the third pulse was long. Chirps with three pulses of increasing duration of 5, 20 and 50 ms elicited phonotaxis, but the chirps were not attractive when played in reverse order. This demonstrates specific, pulse duration-dependent effects while sequences of pulses are processed. The data are in agreement with a mechanism in which processing of a sound pulse has an effect on the processing of the subsequent pulse, as outlined in the flow of activity in a delay-line and coincidence-detector circuit. Additionally our data reveal a substantial increase in the gain of phonotaxis, when the number of pulses of a chirp is increased from two to three. © 2017 The Authors.

Inter-pulse high-resolution gamma-ray spectra using a 14 MeV pulsed neutron generator

USGS Publications Warehouse

Evans, L.G.; Trombka, J.I.; Jensen, D.H.; Stephenson, W.A.; Hoover, R.A.; Mikesell, J.L.; Tanner, A.B.; Senftle, F.E.

1984-01-01

A neutron generator pulsed at 100 s-1 was suspended in an artificial borehole containing a 7.7 metric ton mixture of sand, aragonite, magnetite, sulfur, and salt. Two Ge(HP) gamma-ray detectors were used: one in a borehole sonde, and one at the outside wall of the sample tank opposite the neutron generator target. Gamma-ray spectra were collected by the outside detector during each of 10 discrete time windows during the 10 ms period following the onset of gamma-ray build-up after each neutron burst. The sample was measured first when dry and then when saturated with water. In the dry sample, gamma rays due to inelastic neutron scattering, neutron capture, and decay were counted during the first (150 ??s) time window. Subsequently only capture and decay gamma rays were observed. In the wet sample, only neutron capture and decay gamma rays were observed. Neutron capture gamma rays dominated the spectrum during the period from 150 to 400 ??s after the neutron burst in both samples, but decreased with time much more rapidly in the wet sample. A signal-to-noise-ratio (S/N) analysis indicates that optimum conditions for neutron capture analysis occurred in the 350-800 ??s window. A poor S/N in the first 100-150 ??s is due to a large background continuum during the first time interval. Time gating can be used to enhance gamma-ray spectra, depending on the nuclides in the target material and the reactions needed to produce them, and should improve the sensitivity of in situ well logging. ?? 1984.

Quantification of the proportion of motor neurons recruited by transcranial electrical stimulation during intraoperative motor evoked potential monitoring.

PubMed

Tsutsui, Shunji; Yamada, Hiroshi; Hashizume, Hiroshi; Minamide, Akihito; Nakagawa, Yukihiro; Iwasaki, Hiroshi; Yoshida, Munehito

2013-12-01

Transcranial motor evoked potentials (TcMEPs) are widely used to monitor motor function during spinal surgery. However, they are much smaller and more variable in amplitude than responses evoked by maximal peripheral nerve stimulation, suggesting that a limited number of spinal motor neurons to the target muscle are excited by transcranial stimulation. The aim of this study was to quantify the proportion of motor neurons recruited during TcMEP monitoring under general anesthesia. In twenty patients who underwent thoracic and/or lumbar spinal surgery with TcMEP monitoring, the triple stimulation technique (TST) was applied to the unilateral upper arm intraoperatively. Total intravenous anesthesia was employed. Trains of four stimuli were delivered with maximal intensity and an inter-pulse interval of 1.5 ms. TST responses were recorded from the abductor digiti minimi muscle, and the negative peak amplitude and area were measured and compared between the TST test (two collisions between transcranial and proximal and distal peripheral stimulation) and control response (two collisions between two proximal and one distal peripheral stimulation). The highest degree of superimposition of the TST test and control responses was chosen from several trials per patient. The average ratios (test:control) were 17.1 % (range 1.8-38 %) for the amplitudes and 21.6 % (range 2.9-40 %) for the areas. The activity of approximately 80 % of the motor units to the target muscle cannot be detected by TcMEP monitoring. Therefore, changes in evoked potentials must be interpreted cautiously when assessing segmental motor function with TcMEP monitoring.

A biometric method to secure telemedicine systems.

PubMed

Zhang, G H; Poon, Carmen C Y; Li, Ye; Zhang, Y T

2009-01-01

Security and privacy are among the most crucial issues for data transmission in telemedicine systems. This paper proposes a solution for securing wireless data transmission in telemedicine systems, i.e. within a body sensor network (BSN), between the BSN and server as well as between the server and professionals who have assess to the server. A unique feature of this solution is the generation of random keys by physiological data (i.e. a biometric approach) for securing communication at all 3 levels. In the performance analysis, inter-pulse interval of photoplethysmogram is used as an example to generate these biometric keys to protect wireless data transmission. The results of statistical analysis and computational complexity suggest that this type of key is random enough to make telemedicine systems resistant to attacks.

Particle energy distributions and metastable atoms in transient low pressure interpulse microwave plasma

NASA Astrophysics Data System (ADS)

Pandey, Shail; Nath Patel, Dudh; Ram Baitha, Anuj; Bhattacharjee, Sudeep

2015-12-01

The electron energies and its distribution function are measured in non-equilibrium transient pulsed microwave plasmas in the interpulse regime using a retarding field electron energy analyzer. The plasmas are driven to different initial conditions by varying the electromagnetic (EM) wave pulse duration, peak power, or the wave frequency. Two cases of wave excitation are investigated: (i) short-pulse (pulse duration, t w ~ 1 μs), high-power (~60 kW) waves of 9.45 GHz and (ii) medium-pulse (t w ~ 20 μs), and moderate power waves of ~3 kW at 2.45 GHz. It is found that high-power, short-duration pulses lead to a significantly different electron energy probability function (EEPF) in the interpulse phase—a Maxwellian with a bump on the tail, although the average energy per pulse (~60 mJ) is maintained the same in the two modes of wave excitation. Electrons with energies  >250 eV are found to exist in the discharge in the both cases. Another subset of experiments is performed to delineate the effect of the wave frequency and the peak power on EEPF. A traveling wave tube (TWT) amplifier based microwave source for generating pulsed plasma (t w  =  230 μs) in a wide frequency range (6-18 GHz) is employed for this purpose. Further experiments on measurements of metastable density using optical emission spectroscopy and ion energy analyzer have been carried out. By tailoring the EEPF of the transient plasma and metastable densities, new applications in plasma processing, chemistry and biology can be realized in the interpulse phase of the discharge.

Radiation reflection from star surface reveals the mystery of interpulse shift and appearance of high frequency components in the Crab pulsar

NASA Astrophysics Data System (ADS)

Kontorovich, V. M.; Trofymenko, S. V.

2017-12-01

A new mechanism of radiation emission in the polar gap of a pulsar is discussed. It is based on the curvature radiation which is emitted by positrons moving towards the surface of neutron star along field lines of the inclined magnetic field and reflects from the surface. This mechanism explains the mystery of the interpulse shift and appearance of additional components in the emission of Crab pulsar at high frequencies discovered by Moffett and Hankins twenty years ago. We discuss coherence, energy flux and spectrum of the reflected radiation, appearance and disappearance of the interpulse position shift with the frequency increase. It is also possible that a nonlinear reflection (stimulated scattering) from the star surface is observed in the form of HF components. The frequency drift of these components, discovered by Hankins, Jones and Eilek, is discussed. The nonlinear reflection is associated with “Wood’s anomaly” at the diffracted waves grazing along the star surface. Two components can arise due to slow and fast waves which are present in the magnetospheric plasma. The possible scheme of their appearance due to birefringence at the reflection is also proposed.

Influence of sodium valproate on medium-late luteal phase pulsatile LH secretion in normal women.

PubMed

Lado Abeal, J; Rey Losada, C; Cabezas Agricola, J M; Cabezas-Cerrato, J

1994-01-01

It is not known whether gamma-aminobutyric acid (GABA) is involved in control of pulsatile LH secretion in human beings. Previous work by our group has shown that manipulation of the GABAergic system with sodium valproate does not affect pulsatile LH secretion in normal women in the late follicular phase. However, it has been suggested that steroid levels are critical for the influence of GABA upon hormone secretion; in particular, progesterone has been said to enhance inhibition by GABA. In this work we studied the effect of sodium valproate on pulsatile LH secretion in medium-late luteal phase of normal women. Six normal young women were studied over an 8-hour period in two successive menstrual cycles. On each occasion blood samples were taken every 10 minutes between 1000 and 1800 h. We administered 400 mg of sodium valproate every 8 hours on the 7 days preceding their second cycle and additional 400 mg at 0900 and 1400 h on the day of the study. Ovulation day was estimated by means of serial ovarian ultrasound examinations and confirmed by serum progesterone concentrations. In each cycle, LH, oestradiol and progesterone were determined by radioimmunoassay and sodium valproate by repolarization fluorescence spectrophotometry. The series of LH levels was smoothed for 1-minute sampling periods by means of a spline function and analysed by means of a program developed in our laboratory and written in Fortran 77. The program deconvolved the signal and calculated the pulse area, pulse duration, interpulse interval and number of pulses. LH pulse identification on the deconvolved signals was performed using our own method based on Friedman's non-parametric statistic. The statistical significance of differences between parameters was estimated using the Mann-Whitney test and Wilcoxon signed rank test. There were no significant differences in LH pulse area, pulse duration, interpulse interval or number of pulses with the administration of sodium valproate. Activation of the GABAergic system with sodium valproate had no biologically significant effect on the mid-late luteal phase pulsatile LH secretion in normal women.

Individuality embedded in the isolation calls of captive beluga whales (Delphinapterus leucas).

PubMed

Mishima, Yuka; Morisaka, Tadamichi; Itoh, Miho; Matsuo, Ikuo; Sakaguchi, Aiko; Miyamoto, Yoshinori

2015-01-01

Species with fission-fusion social systems tend to exchange individualized contact calls to maintain group cohesion. Signature whistles by bottlenose dolphins are unique compared to the contact calls of other non-human animals in that they include identity information independent of voice cues. Further, dolphins copy the signatures of conspecifics and use them to label specific individuals. Increasing our knowledge of the contact calls of other cetaceans that have a fluid social structure may thus help us better understand the evolutionary and adaptive significance of all forms of individually distinctive calls. It was recently reported that one type of broadband pulsed sounds (PS1), rather than whistles, may function as individualized contact calls in captive belugas. The objective of this study was to assess the function and individual distinctiveness of PS1 calls in an isolation context. Recordings were made from five captive belugas, including both sexes and various ages. PS1 was the predominant call type (38 % in total) out of five broader sound categories. One sub-adult and three adults had individually distinctive and stereotyped pulse repetition pattern in PS1; one calf showed no clear stereotyped pulse repetition pattern. While visual inspection of the PS1 power spectra uncovered no apparent individual specificity, statistical analyses revealed that both temporal and spectral parameters had inter-individual differences and that there was greater inter-individual than intra-individual variability. Discriminant function analysis based on five temporal and spectral parameters classified PS1 calls into individuals with an overall correct classification rate of 80.5 %, and the most informative parameter was the average Inter-pulse interval, followed by peak frequency. These results suggest that belugas use individually distinctive contact calls in an isolation context. If belugas encode signature information in PS1 calls, as seen in bottlenose dolphins, the pulse repetition pattern may be the carrier, as it is individually stereotyped and appears to require vocal development. This idea is supported by the finding that the average inter-pulse interval is the most powerful discriminator in discriminant analysis. Playback experiments will elucidate which parameters are perceived as individual characteristics, and whether one of the parameters functions as a signature.

Observation of Pulsed Gamma Rays with Energies Greater than 250 keV from the Crab Nebula Pulsar NP 0532. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Orwig, L. E.

1971-01-01

Data from a balloon flight experiment using an Na I scintillation spectrometer were analyzed for gamma ray pulsation. The payload was carried to a nominal atmospheric depth of 3.5 g/cm2. A superposed epoch analysis was performed on a 12,000 second portion of the data spanning a total time interval of 16,700 seconds at float altitude. A positive pulsed contribution was observed at the expected apparent frequency of NP 0532 having the typical double pulse structure. The results indicate a time-averaged pulse photon flux of 0.00144 + or - 0.00057 photons/sq cm/sec in the energy interval from 250 keV to 2.3 MeV. This represents a time-averaged pulsed power of 0.000649 + or - 0.000257 keV/sq cm/sec/keV. The ratio of interpulse to main pulse was found to be 2.4 + or - 1.9. The analysis indicates a positive photon flux from 250 keV to 725 keV of 0.00120 + or - 0.00052 photons/sq cm/sec.

Determination of inadvertent atrial capture during para-Hisian pacing.

PubMed

Obeyesekere, Manoj; Leong-Sit, Peter; Skanes, Allan; Krahn, Andrew; Yee, Raymond; Gula, Lorne J; Bennett, Matthew; Klein, George J

2011-08-01

Inadvertent capture of the atrium will lead to spurious results during para-Hisian pacing. We sought to establish whether the stimulation-to-atrial electrogram interval at the proximal coronary sinus (stim-PCS) or high right atrium (stim-HRA) could signal inadvertent atrial capture. Para-Hisian pacing with and without intentional atrial capture was performed in 31 patients. Stim-HRA and stim-PCS intervals were measured with atrial capture, His plus para-Hisian ventricular (H+V) capture, and para-Hisian ventricular (V) capture alone. The mean stim-HRA interval was significantly shorter with atrial capture (66 ± 18 ms) than with H+V (121 ± 27 ms, P < 0.001) or V capture alone (174 ± 38 ms, P < 0.001). The mean stim-PCS interval was significantly shorter with atrial capture (51 ± 16 ms) than with H+V (92 ± 22 ms, P<0.001) or V capture alone (146 ± 33 ms, P < 0.001). A stim-PCS < 60 ms (stim-HRA < 70 ms) was observed only with atrial capture. A stim-PCS >90 ms (stim-HRA >100 ms) was observed only in the absence of atrial capture. A stim-HRA of < 85 ms was highly specific and stim-PCS of < 85 ms highly sensitive at identifying atrial capture. Stim-HRA intervals of 75 to 97 ms and stim-PCS intervals of 65 to 88 ms were observed with either atrial, His, or para-Hisian ventricular capture without atrial capture. In this overlap zone, all patients demonstrated a stim-PCS or stim-HRA interval prolongation of at least 20 ms when the catheter was advanced to avoid deliberate atrial pacing. The QRS morphology was of limited value in distinguishing atrial capture due to concurrent ventricular or H+V capture, as observed in 20 of 31 (65%) patients. Stim-PCS and stim-HRA intervals can be used to monitor for inadvertent atrial capture during para-Hisian pacing. A stim-PCS < 60 ms (or stim-HRA < 70 ms) and stim-PCS > 90 ms (or stim-HRA > 100 ms) were observed only with and without atrial capture, respectively, but there was significant overlap between these values. Deliberate atrial capture and loss of capture reliably identifies atrial capture regardless of intervals.

High dynamic range infrared radiometry and imaging

NASA Technical Reports Server (NTRS)

Coon, Darryl D.; Karunasiri, R. P. G.; Bandara, K. M. S. V.

1988-01-01

The use is described of cryogenically cooled, extrinsic silicon infrared detectors in an unconventional mode of operation which offers an unusually large dynamic range. The system performs intensity-to-frequency conversion at the focal plane via simple circuits with very low power consumption. The incident IR intensity controls the repetition rate of short duration output pulses over a pulse rate dynamic range of about 10(6). Theory indicates the possibility of monotonic and approx. linear response over the full dynamic range. A comparison between the theoretical and the experimental results shows that the model provides a reasonably good description of experimental data. Some measurements of survivability with a very intense IR source were made on these devices and found to be very encouraging. Evidence continues to indicate that some variations in interpulse time intervals are deterministic rather than probabilistic.

Spatiotemporal analysis of turbulent jets enabled by 100-kHz, 100-ms burst-mode particle image velocimetry

NASA Astrophysics Data System (ADS)

Miller, Joseph D.; Jiang, Naibo; Slipchenko, Mikhail N.; Mance, Jason G.; Meyer, Terrence R.; Roy, Sukesh; Gord, James R.

2016-12-01

100-kHz particle image velocimetry (PIV) is demonstrated using a double-pulsed, burst-mode laser with a burst duration up to 100 ms. This enables up to 10,000 time-sequential vector fields for capturing a temporal dynamic range spanning over three orders of magnitude in high-speed turbulent flows. Pulse doublets with inter-pulse spacing of 2 µs and repetition rate of 100 kHz are generated using a fiber-based oscillator and amplified through an all-diode-pumped, burst-mode amplifier. A physics-based model of pulse doublet amplification in the burst-mode amplifier is developed and used to accurately predict oscillator pulse width and pulse intensity inputs required to generate equal-energy pulse doublets at 532 nm for velocity measurements. The effect of PIV particle response and high-speed-detector limitations on the spatial and temporal resolution are estimated in subsonic turbulent jets. An effective spatial resolution of 266-275 µm and temporal resolution of 10 µs are estimated from the 8 × 8 pixel correlation window and inter-doublet time spacing, respectively. This spatiotemporal resolution is sufficient for quantitative assessment of integral time and length scales in highly turbulent jets with Reynolds numbers in the range 15,000-50,000. The temporal dynamic range of the burst-mode PIV measurement is 1200, limited by the 85-ms high-energy portion of the burst and 30-kHz high-frequency noise limit.

ECG parameters predict left ventricular conduction delay in patients with left ventricular dysfunction.

PubMed

Pastore, Gianni; Maines, Massimiliano; Marcantoni, Lina; Zanon, Francesco; Noventa, Franco; Corbucci, Giorgio; Baracca, Enrico; Aggio, Silvio; Picariello, Claudio; Lanza, Daniela; Rigatelli, Gianluca; Carraro, Mauro; Roncon, Loris; Barold, S Serge

2016-12-01

Estimating left ventricular electrical delay (Q-LV) from a 12-lead ECG may be important in evaluating cardiac resynchronization therapy (CRT). The purpose of this study was to assess the impact of Q-LV interval on ECG configuration. One hundred ninety-two consecutive patients undergoing CRT implantation were divided electrocardiographically into 3 groups: left bundle branch block (LBBB), right bundle branch block (RBBB), and nonspecific intraventricular conduction delay (IVCD). The IVCD group was further subdivided into 81 patients with left (L)-IVCD and 15 patients with right (R)-IVCD (resembling RBBB, but without S wave in leads I and aVL). The Q-LV interval in the different groups and the relationship between ECG parameters and the maximum Q-LV interval were analyzed. Patients with LBBB presented a long Q-LV interval (147.7 ± 14.6 ms, all exceeding cutoff value of 110 ms), whereas RBBB patients presented a very short Q-LV interval (75.2 ± 16.3 ms, all <110 ms). Patients with an IVCD displayed a wide range of Q-LV intervals. In L-IVCD, mid-QRS notching/slurring showed the strongest correlation with a longer Q-LV interval, followed, in decreasing order, by QRS duration >150 ms and intrinsicoid deflection >60 ms. Isolated mid-QRS notching/slurring predicted Q-LV interval >110 ms in 68% of patients. The R-IVCD group presented an unexpectedly longer Q-LV interval (127.0 ± 12.5 ms; 13/15 patients had Q-LV >110 ms). Patients with LBBB have a very prolonged Q-LV interval. Mid-QRS notching in lateral leads strongly predicts a longer Q-LV interval in L-IVCD patients. Patients with R-IVCD constitute a subgroup of patients with a long Q-LV interval. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Failure to suppress low-frequency neuronal oscillatory activity underlies the reduced effectiveness of random patterns of deep brain stimulation.

PubMed

McConnell, George C; So, Rosa Q; Grill, Warren M

2016-06-01

Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established treatment for the motor symptoms of Parkinson's disease (PD). However, the mechanisms of action of DBS are unknown. Random temporal patterns of DBS are less effective than regular DBS, but the neuronal basis for this dependence on temporal pattern of stimulation is unclear. Using a rat model of PD, we quantified the changes in behavior and single-unit activity in globus pallidus externa and substantia nigra pars reticulata during high-frequency STN DBS with different degrees of irregularity. Although all stimulus trains had the same average rate, 130-Hz regular DBS more effectively reversed motor symptoms, including circling and akinesia, than 130-Hz irregular DBS. A mixture of excitatory and inhibitory neuronal responses was present during all stimulation patterns, and mean firing rate did not change during DBS. Low-frequency (7-10 Hz) oscillations of single-unit firing times present in hemiparkinsonian rats were suppressed by regular DBS, and neuronal firing patterns were entrained to 130 Hz. Irregular patterns of DBS less effectively suppressed 7- to 10-Hz oscillations and did not regularize firing patterns. Random DBS resulted in a larger proportion of neuron pairs with increased coherence at 7-10 Hz compared with regular 130-Hz DBS, which suggested that long pauses (interpulse interval >50 ms) during random DBS facilitated abnormal low-frequency oscillations in the basal ganglia. These results suggest that the efficacy of high-frequency DBS stems from its ability to regularize patterns of neuronal firing and thereby suppress abnormal oscillatory neural activity within the basal ganglia. Copyright © 2016 the American Physiological Society.

Multi-delay, phase coherent pulse pair generation for precision Ramsey-frequency comb spectroscopy.

PubMed

Morgenweg, J; Eikema, K S E

2013-03-11

We demonstrate the generation of phase-stable mJ-pulse pairs at programmable inter-pulse delays up to hundreds of nanoseconds. A detailed investigation of potential sources for phase shifts during the parametric amplification of the selected pulses from a Ti:Sapphire frequency comb is presented, both numerically and experimentally. It is shown that within the statistical error of the phase measurement of 10 mrad, there is no dependence of the differential phase shift over the investigated inter-pulse delay range of more than 300 ns. In combination with nonlinear upconversion of the amplified pulses, the presented system will potentially enable short wavelength (<100 nm), multi-transition Ramsey-frequency comb spectroscopy at the kHz-level.

Spike-train acquisition, analysis and real-time experimental control using a graphical programming language (LabView).

PubMed

Nordstrom, M A; Mapletoft, E A; Miles, T S

1995-11-01

A solution is described for the acquisition on a personal computer of standard pulses derived from neuronal discharge, measurement of neuronal discharge times, real-time control of stimulus delivery based on specified inter-pulse interval conditions in the neuronal spike train, and on-line display and analysis of the experimental data. The hardware consisted of an Apple Macintosh IIci computer and a plug-in card (National Instruments NB-MIO16) that supports A/D, D/A, digital I/O and timer functions. The software was written in the object-oriented graphical programming language LabView. Essential elements of the source code of the LabView program are presented and explained. The use of the system is demonstrated in an experiment in which the reflex responses to muscle stretch are assessed for a single motor unit in the human masseter muscle.

The prevalence and significance of a short QT interval in 18,825 low-risk individuals including athletes.

PubMed

Dhutia, Harshil; Malhotra, Aneil; Parpia, Sameer; Gabus, Vincent; Finocchiaro, Gherardo; Mellor, Greg; Merghani, Ahmed; Millar, Lynne; Narain, Rajay; Sheikh, Nabeel; Behr, Elijah R; Papadakis, Michael; Sharma, Sanjay

2016-01-01

The short QT syndrome is a cardiac channelopathy characterised by accelerated repolarisation which manifests as a short QT interval on the ECG. The definition of a short QT interval is debated, ranging from <390 to ≤320 ms, and its clinical significance in healthy young individuals is unknown. We assessed the prevalence and medium-term significance of an isolated short QT interval in a diverse young British population. Between 2005 and 2013, 18 825 apparently healthy people aged 14-35 years underwent cardiovascular evaluation with history, physical examination and ECG. QT intervals were measured by cardiologists using 4 recommended guidelines (Seattle 2013, Heart Rhythm Society 2013, European Society of Cardiology 2010 and American Heart Association 2009). The prevalence of a short QT interval was 0.1% (26 patients, ≤320 ms), 0.2% (44 patients, ≤330 ms), 7.9% (1478 patients, <380 ms), 15.8% (2973 patients, <390 ms). Male gender and Afro-Caribbean ethnicity had the strongest association with short QT intervals. Athletes had shorter QT intervals than non-athletes but athletic status did not predict short QT intervals. Individuals with short QT intervals ≤320 ms did not report syncope or a sinister family history, and during a follow-up period of 5.3±1.2 years, there were no deaths in this group. The prevalence of a short QT interval depends on the recommended cut-off value. Even at values ≤320 ms, there was an excellent medium-term prognosis among 14 people followed. We conclude that a definition of ≤320 ms is realistic to prevent overdiagnosis and excessive investigations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

[Effect of heat shock on courtship behavior, sound production, and learning in comparison with the brain content of LIMK1 in Drosophila melanogaster males with altered structure of the LIMK1 gene].

PubMed

Nikitina, E A; Kaminskaya, A N; Molotkov, D A; Popov, A V; Savvateeva-Popova, E V

2014-01-01

In this paper we present results of a comprehensive analysis of the effect of heat shock at different stages of ontogenesis (adult stage, development of the mushroom bodies and the central complex) on courtship behavior (latency, duration and efficacy of courtship), sound production (pulse interval, dispersion of interpulse interval, the percentage of distorted pulses, the mean duration of the pulse parcels), learning and memory formation compared with the content of isoforms LIMK1 in Drosophila melanogaster male with altered structure of the limk1 gene. The heat shock is shown to affect the behavior parameters and LIMK1 content in analyzed strains of Drosophila. The most pronounced effect of the heat shock was observed at the stage of development of the central complex (CC). Heat shock at CC and adult restores the ability of learning and memory formation in the mutant strain agn(ts3), which normally is not able to learn and form memory. Correlations between changes of content of isoforms LIMK1 and behavioral parameters due to heat shock have not been established.

Coffee, alcohol, smoking, physical activity and QT interval duration: results from the Third National Health and Nutrition Examination Survey.

PubMed

Zhang, Yiyi; Post, Wendy S; Dalal, Darshan; Blasco-Colmenares, Elena; Tomaselli, Gordon F; Guallar, Eliseo

2011-02-28

Abnormalities in the electrocardiographic QT interval duration have been associated with an increased risk of ventricular arrhythmias and sudden cardiac death. However, there is substantial uncertainty about the effect of modifiable factors such as coffee intake, cigarette smoking, alcohol consumption, and physical activity on QT interval duration. We studied 7795 men and women from the Third National Health and Nutrition Survey (NHANES III, 1988-1994). Baseline QT interval was measured from the standard 12-lead electrocardiogram. Coffee and tea intake, alcohol consumption, leisure-time physical activities over the past month, and lifetime smoking habits were determined using validated questionnaires during the home interview. In the fully adjusted model, the average differences in QT interval comparing participants drinking ≥6 cups/day to those who did not drink any were -1.2 ms (95% CI -4.4 to 2.0) for coffee, and -2.0 ms (-11.2 to 7.3) for tea, respectively. The average differences in QT interval duration comparing current to never smokers was 1.2 ms (-0.6 to 2.9) while the average difference in QT interval duration comparing participants drinking ≥7 drinks/week to non-drinkers was 1.8 ms (-0.5 to 4.0). The age, race/ethnicity, and RR-interval adjusted differences in average QT interval duration comparing men with binge drinking episodes to non-drinkers or drinkers without binge drinking were 2.8 ms (0.4 to 5.3) and 4.0 ms (1.6 to 6.4), respectively. The corresponding differences in women were 1.1 (-2.9 to 5.2) and 1.7 ms (-2.3 to 5.7). Finally, the average differences in QT interval comparing the highest vs. the lowest categories of total physical activity was -0.8 ms (-3.0 to 1.4). Binge drinking was associated with longer QT interval in men but not in women. QT interval duration was not associated with other modifiable factors including coffee and tea intake, smoking, and physical activity.

Coffee, Alcohol, Smoking, Physical Activity and QT Interval Duration: Results from the Third National Health and Nutrition Examination Survey

PubMed Central

Zhang, Yiyi; Post, Wendy S.; Dalal, Darshan; Blasco-Colmenares, Elena; Tomaselli, Gordon F.; Guallar, Eliseo

2011-01-01

Background Abnormalities in the electrocardiographic QT interval duration have been associated with an increased risk of ventricular arrhythmias and sudden cardiac death. However, there is substantial uncertainty about the effect of modifiable factors such as coffee intake, cigarette smoking, alcohol consumption, and physical activity on QT interval duration. Methods We studied 7795 men and women from the Third National Health and Nutrition Survey (NHANES III, 1988–1994). Baseline QT interval was measured from the standard 12-lead electrocardiogram. Coffee and tea intake, alcohol consumption, leisure-time physical activities over the past month, and lifetime smoking habits were determined using validated questionnaires during the home interview. Results In the fully adjusted model, the average differences in QT interval comparing participants drinking ≥6 cups/day to those who did not drink any were −1.2 ms (95% CI −4.4 to 2.0) for coffee, and −2.0 ms (−11.2 to 7.3) for tea, respectively. The average differences in QT interval duration comparing current to never smokers was 1.2 ms (−0.6 to 2.9) while the average difference in QT interval duration comparing participants drinking ≥7 drinks/week to non-drinkers was 1.8 ms (−0.5 to 4.0). The age, race/ethnicity, and RR-interval adjusted differences in average QT interval duration comparing men with binge drinking episodes to non-drinkers or drinkers without binge drinking were 2.8 ms (0.4 to 5.3) and 4.0 ms (1.6 to 6.4), respectively. The corresponding differences in women were 1.1 (−2.9 to 5.2) and 1.7 ms (−2.3 to 5.7). Finally, the average differences in QT interval comparing the highest vs. the lowest categories of total physical activity was −0.8 ms (−3.0 to 1.4). Conclusion Binge drinking was associated with longer QT interval in men but not in women. QT interval duration was not associated with other modifiable factors including coffee and tea intake, smoking, and physical activity. PMID:21386989

Cueing listeners to attend to a target talker progressively improves word report as the duration of the cue-target interval lengthens to 2,000 ms.

PubMed

Holmes, Emma; Kitterick, Padraig T; Summerfield, A Quentin

2018-04-25

Endogenous attention is typically studied by presenting instructive cues in advance of a target stimulus array. For endogenous visual attention, task performance improves as the duration of the cue-target interval increases up to 800 ms. Less is known about how endogenous auditory attention unfolds over time or the mechanisms by which an instructive cue presented in advance of an auditory array improves performance. The current experiment used five cue-target intervals (0, 250, 500, 1,000, and 2,000 ms) to compare four hypotheses for how preparatory attention develops over time in a multi-talker listening task. Young adults were cued to attend to a target talker who spoke in a mixture of three talkers. Visual cues indicated the target talker's spatial location or their gender. Participants directed attention to location and gender simultaneously ("objects") at all cue-target intervals. Participants were consistently faster and more accurate at reporting words spoken by the target talker when the cue-target interval was 2,000 ms than 0 ms. In addition, the latency of correct responses progressively shortened as the duration of the cue-target interval increased from 0 to 2,000 ms. These findings suggest that the mechanisms involved in preparatory auditory attention develop gradually over time, taking at least 2,000 ms to reach optimal configuration, yet providing cumulative improvements in speech intelligibility as the duration of the cue-target interval increases from 0 to 2,000 ms. These results demonstrate an improvement in performance for cue-target intervals longer than those that have been reported previously in the visual or auditory modalities.

Time-order errors and standard-position effects in duration discrimination: An experimental study and an analysis by the sensation-weighting model.

PubMed

Hellström, Åke; Rammsayer, Thomas H

2015-10-01

Studies have shown that the discriminability of successive time intervals depends on the presentation order of the standard (St) and the comparison (Co) stimuli. Also, this order affects the point of subjective equality. The first effect is here called the standard-position effect (SPE); the latter is known as the time-order error. In the present study, we investigated how these two effects vary across interval types and standard durations, using Hellström's sensation-weighting model to describe the results and relate them to stimulus comparison mechanisms. In Experiment 1, four modes of interval presentation were used, factorially combining interval type (filled, empty) and sensory modality (auditory, visual). For each mode, two presentation orders (St-Co, Co-St) and two standard durations (100 ms, 1,000 ms) were used; half of the participants received correctness feedback, and half of them did not. The interstimulus interval was 900 ms. The SPEs were negative (i.e., a smaller difference limen for St-Co than for Co-St), except for the filled-auditory and empty-visual 100-ms standards, for which a positive effect was obtained. In Experiment 2, duration discrimination was investigated for filled auditory intervals with four standards between 100 and 1,000 ms, an interstimulus interval of 900 ms, and no feedback. Standard duration interacted with presentation order, here yielding SPEs that were negative for standards of 100 and 1,000 ms, but positive for 215 and 464 ms. Our findings indicate that the SPE can be positive as well as negative, depending on the interval type and standard duration, reflecting the relative weighting of the stimulus information, as is described by the sensation-weighting model.

Frequency domain tailoring for intra-pulse frequency mixing.

PubMed

Ernotte, G; Lassonde, P; Légaré, F; Schmidt, B E

2016-10-17

Generating mid infrared (MIR) pulses by difference frequency generation (DFG) is often a trade-off between the maximum stability given by all-inline intra-pulse arrangements and the independent control of pulse parameters with inter-pulse pump-probe like scenarios. We propose a coalescence between both opposing approaches by realizing an all-inline inter-pulse DFG scheme employing a 4-f setup. This allows independent manipulation of the amplitude, delay and polarization of the two corresponding spectral side bands of a supercontinuum source while maintaining 20 attoseconds jitter without any feedback stabilization. After filamentation in air, the broadened Ti:Sa spectrum is tailored in a 4-f setup to generate tunable MIR pulses. In this manner, 2 µm, 4.8 µJ, 26.5 fs and carrier-envelope-phase (CEP) stabilized pulses are generated in a single DFG stage.

A Variable Oscillator Underlies the Measurement of Time Intervals in the Rostral Medial Prefrontal Cortex during Classical Eyeblink Conditioning in Rabbits.

PubMed

Caro-Martín, C Rocío; Leal-Campanario, Rocío; Sánchez-Campusano, Raudel; Delgado-García, José M; Gruart, Agnès

2015-11-04

We were interested in determining whether rostral medial prefrontal cortex (rmPFC) neurons participate in the measurement of conditioned stimulus-unconditioned stimulus (CS-US) time intervals during classical eyeblink conditioning. Rabbits were conditioned with a delay paradigm consisting of a tone as CS. The CS started 50, 250, 500, 1000, or 2000 ms before and coterminated with an air puff (100 ms) directed at the cornea as the US. Eyelid movements were recorded with the magnetic search coil technique and the EMG activity of the orbicularis oculi muscle. Firing activities of rmPFC neurons were recorded across conditioning sessions. Reflex and conditioned eyelid responses presented a dominant oscillatory frequency of ≈12 Hz. The firing rate of each recorded neuron presented a single peak of activity with a frequency dependent on the CS-US interval (i.e., ≈12 Hz for 250 ms, ≈6 Hz for 500 ms, and≈3 Hz for 1000 ms). Interestingly, rmPFC neurons presented their dominant firing peaks at three precise times evenly distributed with respect to CS start and also depending on the duration of the CS-US interval (only for intervals of 250, 500, and 1000 ms). No significant neural responses were recorded at very short (50 ms) or long (2000 ms) CS-US intervals. rmPFC neurons seem not to encode the oscillatory properties characterizing conditioned eyelid responses in rabbits, but are probably involved in the determination of CS-US intervals of an intermediate range (250-1000 ms). We propose that a variable oscillator underlies the generation of working memories in rabbits. The way in which brains generate working memories (those used for the transient processing and storage of newly acquired information) is still an intriguing question. Here, we report that the firing activities of neurons located in the rostromedial prefrontal cortex recorded in alert behaving rabbits are controlled by a dynamic oscillator. This oscillator generated firing frequencies in a variable band of 3-12 Hz depending on the conditioned stimulus-unconditioned stimulus intervals (1 s, 500 ms, 250 ms) selected for classical eyeblink conditioning of behaving rabbits. Shorter (50 ms) and longer (2 s) intervals failed to activate the oscillator and prevented the acquisition of conditioned eyelid responses. This is an unexpected mechanism to generate sustained firing activities in neural circuits generating working memories. Copyright © 2015 the authors 0270-6474/15/3514809-13$15.00/0.

Dispersion of the corrected QT interval in the electrocardiogram of the ex-prisoners of war.

PubMed

Corović, Naima; Duraković, Zijad; Misigoj-Duraković, Marjeta

2003-04-01

The study of electrocardiograms (ECGs) was performed in a subgroup of 181 men, ex-prisoners of war with mean age 35.8+/-11.0 years and mean duration of imprisonment 164.5+/-87.1 days, chosen at random from the total sample of released prisoners (N=1458). The control group was pair-matched. The analysis of ECGs was done according to the Minnesota code, and Bazett's formula gave the values of the corrected QT interval (QT(c)). The dispersion of the QT(c) interval is determined by the difference between the longest and the shortest measured QT(c) interval in each ECG lead. The results of descriptive statistics in the group of ex-prisoners showed the range of QT(c) dispersion of 8.0-122.0 ms (mean 52.4+/-21.6 ms), while in the control group the range was 6.0-72.0 ms (mean 30.4+/-13.8 ms) (df=360, t=11.536; P<0.001). The QT(c) interval from 422.0 to 480.0 ms had 60.2% ex-prisoners and 30.4% controls, while a QT(c) interval over 480.0 ms had 19.3% ex-prisoners and 1.10% controls (P<0.0001). In the ex-prisoners group, the QT(c) dispersion over 50 ms was present in 51.4%; of those, a dispersion of 95 ms and more was found in 3.9%, while in the controls a QT(c) dispersion over 50 ms was found in 8.3%, but a dispersion of 95 ms and more was not recorded (P<0.0001). The odds ratio estimated for the prolonged QT(c) interval was 8.467 and for enlarged QT(c) dispersion it was 11.695 in the ex-prisoners versus controls (P<0.001). In conclusion, persons exposed to long-term maltreatment in detention camps have significantly greater QT(c) dispersion, as well as a higher relative risk of prolonged QT(c) interval and greater QT(c) dispersion than a control group.

Temporal-pattern recognition by single neurons in a sensory pathway devoted to social communication behavior

PubMed Central

Carlson, Bruce A.

2010-01-01

Sensory systems often encode stimulus information into the temporal pattern of action potential activity. However, little is known about how the information contained within these patterns is extracted by postsynaptic neurons. Similar to temporal coding by sensory neurons, social information in mormyrid fish is encoded into the temporal patterning of an electric organ discharge (EOD). In the current study, sensitivity to temporal patterns of electrosensory stimuli was found to arise within the midbrain posterior exterolateral nucleus (ELp). Whole-cell patch recordings from ELp neurons in vivo revealed three patterns of interpulse interval (IPI) tuning: low-pass neurons tuned to long intervals, high-pass neurons tuned to short intervals and band-pass neurons tuned to intermediate intervals. Many neurons within each class also responded preferentially to either increasing or decreasing IPIs. Playback of electric signaling patterns recorded from freely behaving fish revealed that the IPI and direction tuning of ELp neurons resulted in selective responses to particular social communication displays characterized by distinct IPI patterns. The postsynaptic potential responses of many neurons indicated a combination of excitatory and inhibitory synaptic input, and the IPI tuning of ELp neurons was directly related to rate-dependent changes in the direction and amplitude of postsynaptic potentials. These results suggest that differences in the dynamics of short-term synaptic plasticity in excitatory and inhibitory pathways may tune central sensory neurons to particular temporal patterns of presynaptic activity. This may represent a general mechanism for the processing of behaviorally-relevant stimulus information encoded into temporal patterns of activity by sensory neurons. PMID:19641105

Temporal-pattern recognition by single neurons in a sensory pathway devoted to social communication behavior.

PubMed

Carlson, Bruce A

2009-07-29

Sensory systems often encode stimulus information into the temporal pattern of action potential activity. However, little is known about how the information contained within these patterns is extracted by postsynaptic neurons. Similar to temporal coding by sensory neurons, social information in mormyrid fish is encoded into the temporal patterning of an electric organ discharge. In the current study, sensitivity to temporal patterns of electrosensory stimuli was found to arise within the midbrain posterior exterolateral nucleus (ELp). Whole-cell patch recordings from ELp neurons in vivo revealed three patterns of interpulse interval (IPI) tuning: low-pass neurons tuned to long intervals, high-pass neurons tuned to short intervals, and bandpass neurons tuned to intermediate intervals. Many neurons within each class also responded preferentially to either increasing or decreasing IPIs. Playback of electric signaling patterns recorded from freely behaving fish revealed that the IPI and direction tuning of ELp neurons resulted in selective responses to particular social communication displays characterized by distinct IPI patterns. The postsynaptic potential responses of many neurons indicated a combination of excitatory and inhibitory synaptic input, and the IPI tuning of ELp neurons was directly related to rate-dependent changes in the direction and amplitude of postsynaptic potentials. These results suggest that differences in the dynamics of short-term synaptic plasticity in excitatory and inhibitory pathways may tune central sensory neurons to particular temporal patterns of presynaptic activity. This may represent a general mechanism for the processing of behaviorally relevant stimulus information encoded into temporal patterns of activity by sensory neurons.

Left ventricular epicardial activation increases transmural dispersion of repolarization in healthy, long QT, and dilated cardiomyopathy dogs.

PubMed

Bai, Rong; Lü, Jiagao; Pu, Jun; Liu, Nian; Zhou, Qiang; Ruan, Yanfei; Niu, Huiyan; Zhang, Cuntai; Wang, Lin; Kam, Ruth

2005-10-01

Benefits of cardiac resynchronization therapy (CRT) are well established. However, less is understood concerning its effects on myocardial repolarization and the potential proarrhythmic risk. Healthy dogs (n = 8) were compared to a long QT interval (LQT) model (n = 8, induced by cesium chloride, CsCl) and a dilated cardiomyopathy with congestive heart failure (DCM-CHF, induced by rapid ventricular pacing, n = 5). Monophasic action potential (MAP) recordings were obtained from the subendocardium, midmyocardium, subepicardium, and the transmural dispersion of repolarization (TDR) was calculated. The QT interval and the interval from the peak to the end of the T wave (T(p-e)) were measured. All these characteristics were compared during left ventricular epicardial (LV-Epi), right ventricular endocardial (RV-Endo), and biventricular (Bi-V) pacing. In healthy dogs, TDR prolonged to 37.54 ms for Bi-V pacing and to 47.16 ms for LV-Epi pacing as compared to 26.75 ms for RV-Endo pacing (P < 0.001), which was parallel to an augmentation in T(p-e) interval (Bi-V pacing, 64.29 ms; LV-Epi pacing, 57.89 ms; RV-Endo pacing, 50.29 ms; P < 0.01). During CsCl exposure, Bi-V and LV-Epi pacing prolonged MAPD, TDR, and T(p-e) interval as compared to RV-Endo pacing. The midmyocardial MAPD (276.30 ms vs 257.35 ms, P < 0.0001) and TDR (33.80 ms vs 27.58 ms, P=0.002) were significantly longer in DCM-CHF dogs than those in healthy dogs. LV-Epi and Bi-V pacing further prolonged the MAPD and TDR in this model. LV-Epi and Bi-V pacing result in prolongation of ventricular repolarization time, and increase of TDR accounted for a parallel augmentation of the T(p-e) interval, which provides evidence that T(p-e) interval accurately represents TDR. These effects are magnified in the LQT and DCM-CHF canine models in addition to their intrinsic transmural heterogeneity in the intact heart. This mechanism may contribute to the development of malignant ventricular arrhythmias, such as torsades de pointes (TdP) in congestive heart failure (CHF) patients treated with CRT.

The prognostic value of the QT interval and QT interval dispersion in all-cause and cardiac mortality and morbidity in a population of Danish citizens.

PubMed

Elming, H; Holm, E; Jun, L; Torp-Pedersen, C; Køber, L; Kircshoff, M; Malik, M; Camm, J

1998-09-01

To evaluate the prognostic value of the QT interval and QT interval dispersion in total and in cardiovascular mortality, as well as in cardiac morbidity, in a general population. The QT interval was measured in all leads from a standard 12-lead ECG in a random sample of 1658 women and 1797 men aged 30-60 years. QT interval dispersion was calculated from the maximal difference between QT intervals in any two leads. All cause mortality over 13 years, and cardiovascular mortality as well as cardiac morbidity over 11 years, were the main outcome parameters. Subjects with a prolonged QT interval (430 ms or more) or prolonged QT interval dispersion (80 ms or more) were at higher risk of cardiovascular death and cardiac morbidity than subjects whose QT interval was less than 360 ms, or whose QT interval dispersion was less than 30 ms. Cardiovascular death relative risk ratios, adjusted for age, gender, myocardial infarct, angina pectoris, diabetes mellitus, arterial hypertension, smoking habits, serum cholesterol level, and heart rate were 2.9 for the QT interval (95% confidence interval 1.1-7.8) and 4.4 for QT interval dispersion (95% confidence interval 1.0-19-1). Fatal and non-fatal cardiac morbidity relative risk ratios were similar, at 2.7 (95% confidence interval 1.4-5.5) for the QT interval and 2.2 (95% confidence interval 1.1-4.0) for QT interval dispersion. Prolongation of the QT interval and QT interval dispersion independently affected the prognosis of cardiovascular mortality and cardiac fatal and non-fatal morbidity in a general population over 11 years.

Electrophysiological markers predicting impeding AV-block during ablation of atrioventricular nodal reentry tachycardia.

PubMed

Fragakis, Nikolaos; Krexi, Lydia; Kyriakou, Panagiota; Sotiriadou, Melani; Lazaridis, Charalambos; Karamanolis, Athanasios; Dalampyras, Panagiotis; Tsakiroglou, Stelios; Skeberis, Vassilios; Tsalikakis, Dimitrios; Vassilikos, Vassilios

2018-01-01

Radiofrequency (RF) ablation of the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT) is occasionally complicated with atrioventricular block (AVB) often predicted by junctional beats (JB) with loss of ventriculo-atrial (VA) conduction. We analyzed retrospectively 153 patients undergoing ablation of SP for typical AVNRT. Patients were divided into two age groups: 127 ≤ 70 years and 26 > 70 years. We analyzed the interval between the atrial electrogram in the His-bundle position and the distal ablation catheter [A(H)-A(RFd)] and between the distal ablation catheter and the proximal coronary sinus catheter [A(RFd)-A(CS)] before RF applications with and without JB. We evaluated if these intervals can be used as predictors of JB incidence and also of JB with loss of VA conduction. We also assessed if age influences the risk of loss of VA conduction. The A(H)-A(RFd) and A(RFd)-A(CS) intervals were significantly shorter in RF applications causing JB than those without JB (33 ± 11 ms vs 39 ± 9 ms, P < 0.001, 14 ± 9 ms vs 20 ± 7 ms, P < 0.001, respectively). The A(H)-A(RFd) and A(RFd)-A(CS) intervals were also significantly shorter in RFs causing JB with VA block than those with VA conduction (29 ± 11 ms vs 35 ± 11 ms, P < 0.001, 8 ± 8 ms vs 17 ± 8 ms, P < 0.001, respectively). Patients > 70 years had shorter intervals (36 ± 11 ms vs 29 ± 8 ms, P  =  0.012, 17 ± 8 ms vs 13 ± 7 ms, P  =  0.027, respectively), while VA block was more common in this age group. The A(H)-A(RFd) and A(RFd)-A(CS) intervals can be used as markers for predicting JB occurrence as well as impending AVB. JB with loss of VA conduction occur more often in older patients possibly due to a higher position of SP. © 2017 Wiley Periodicals, Inc.

Geographic variation in Northwest Atlantic fin whale (Balaenoptera physalus) song: implications for stock structure assessment.

PubMed

Delarue, Julien; Todd, Sean K; Van Parijs, Sofie M; Di Iorio, Lucia

2009-03-01

Passive acoustic data are increasingly being used as a tool for helping to define marine mammal populations and stocks. Fin whale (Balaenoptera physalus) songs present a unique opportunity to determine interstock differences. Their highly stereotyped interpulse interval has been shown to vary between geographic areas and to remain stable over time in some areas. In this study the structure of songs recorded at two geographically close feeding aggregations in the Gulf of St. Lawrence (GSL) and Gulf of Maine (GoM) was compared. Recordings were made from September 2005 through February 2006 in the GSL and intermittently between January 2006 and September 2007 at two locations in the GoM. 6257 pulse intervals corresponding to 19 GSL and 29 GoM songs were measured to characterize songs from both areas. Classification trees showed that GSL songs differ significantly from those in the GoM. The results are consistent with those derived from other stock structure assessment methodologies, such as chemical signature and photoidentification analysis, suggesting that fin whales in these areas may form separate management stocks. Song structure analysis could therefore provide a useful and cost-efficient tool for defining conservation units over temporal and geographical scales relevant to management objectives in fin whales.

Dried blood spot testing for seven steroids using liquid chromatography-tandem mass spectrometry with reference interval determination in the Korean population.

PubMed

Kim, Borahm; Lee, Mi Na; Park, Hyung Doo; Kim, Jong Won; Chang, Yun Sil; Park, Won Soon; Lee, Soo Youn

2015-11-01

Conventional screening for congenital adrenal hyperplasia (CAH) using immunoassays generates a large number of false-positive results. A more specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been introduced to minimize unnecessary follow-ups. However, because of limited data on its use in the Korean population, LC-MS/MS has not yet been incorporated into newborn screening programs in this region. The present study aims to develop and validate an LC-MS/MS method for the simultaneous determination of seven steroids in dried blood spots (DBS) for CAH screening, and to define age-specific reference intervals in the Korean population. We developed and validated an LC-MS/MS method to determine the reference intervals of cortisol, 17-hydroxyprogesterone, 11-deoxycortisol, 21-deoxycortisol, androstenedione, corticosterone, and 11-deoxycorticosterone simultaneously in 453 DBS samples. The samples were from Korean subjects stratified by age group (78 full-term neonates, 76 premature neonates, 89 children, and 100 adults). The accuracy, precision, matrix effects, and extraction recovery were satisfactory for all the steroids at three concentrations; values of intra- and inter-day precision coefficients of variance, bias, and recovery were 0.7-7.7%, -1.5-9.8%, and 49.3-97.5%, respectively. The linearity range was 1-100 ng/mL for cortisol and 0.5-50 ng/mL for other steroids (R²>0.99). The reference intervals were in agreement with the previous reports. This LC-MS/MS method and the reference intervals validated in the Korean population can be successfully applied to analyze seven steroids in DBS for the diagnosis of CAH.

Pediatric Reference Intervals for Free Thyroxine and Free Triiodothyronine

PubMed Central

Jang, Megan; Guo, Tiedong; Soldin, Steven J.

2009-01-01

Background The clinical value of free thyroxine (FT4) and free triiodothyronine (FT3) analysis depends on the reference intervals with which they are compared. We determined age- and sex-specific reference intervals for neonates, infants, and children 0–18 years of age for FT4 and FT3 using tandem mass spectrometry. Methods Reference intervals were calculated for serum FT4 (n = 1426) and FT3 (n = 1107) obtained from healthy children between January 1, 2008, and June 30, 2008, from Children's National Medical Center and Georgetown University Medical Center Bioanalytical Core Laboratory, Washington, DC. Serum samples were analyzed using isotope dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) with deuterium-labeled internal standards. Results FT4 reference intervals were very similar for males and females of all ages and ranged between 1.3 and 2.4 ng/dL for children 1 to 18 years old. FT4 reference intervals for 1- to 12-month-old infants were 1.3–2.8 ng/dL. These 2.5 to 97.5 percentile intervals were much tighter than reference intervals obtained using immunoassay platforms 0.48–2.78 ng/dL for males and 0.85–2.09 ng/dL for females. Similarly, FT3 intervals were consistent and similar for males and females and for all ages, ranging between 1.5 pg/mL and approximately 6.0 pg/mL for children 1 month of age to 18 years old. Conclusions This is the first study to provide pediatric reference intervals of FT4 and FT3 for children from birth to 18 years of age using LC/MS/MS. Analysis using LC/MS/MS provides more specific quantification of thyroid hormones. A comparison of the ultrafiltration tandem mass spectrometric method with equilibrium dialysis showed very good correlation. PMID:19583487

Systematic review of serum steroid reference intervals developed using mass spectrometry.

PubMed

Tavita, Nevada; Greaves, Ronda F

2017-12-01

The aim of this study was to perform a systematic review of the published literature to determine the available serum/plasma steroid reference intervals generated by mass spectrometry (MS) methods across all age groups in healthy subjects and to suggest recommendations to achieve common MS based reference intervals for serum steroids. MEDLINE, EMBASE and PubMed databases were used to conduct a comprehensive search for English language, MS-based reference interval studies for serum/plasma steroids. Selection of steroids to include was based on those listed in the Royal College of Pathologists of Australasia Quality Assurance Programs, Chemical Pathology, Endocrine Program. This methodology has been registered onto the PROSPERO International prospective register of systematic reviews (ID number: CRD42015029637). After accounting for duplicates, a total of 60 manuscripts were identified through the search strategy. Following critical evaluation, a total of 16 studies were selected. Of the 16 studies, 12 reported reference intervals for testosterone, 11 for 17 hydroxy-progesterone, nine for androstenedione, six for cortisol, three for progesterone, two for dihydrotestosterone and only one for aldosterone and dehydroepiandrosterone sulphate. No studies established MS-based reference intervals for oestradiol. As far as we are aware, this report provides the first comparison of the peer reviewed literature for serum/plasma steroid reference intervals generated by MS-based methods. The reference intervals based on these published studies can be used to inform the process to develop common reference intervals, and agreed reporting units for mass spectrometry based steroid methods. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

MPTP-meditated hippocampal dopamine deprivation modulates synaptic transmission and activity-dependent synaptic plasticity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Guoqi; Chen Ying; Huang Yuying

2011-08-01

Parkinson's disease (PD)-like symptoms including learning deficits are inducible by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Therefore, it is possible that MPTP may disturb hippocampal memory processing by modulation of dopamine (DA)- and activity-dependent synaptic plasticity. We demonstrate here that intraperitoneal (i.p.) MPTP injection reduces the number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra (SN) within 7 days. Subsequently, the TH expression level in SN and hippocampus and the amount of DA and its metabolite DOPAC in striatum and hippocampus decrease. DA depletion does not alter basal synaptic transmission and changes pair-pulse facilitation (PPF) of field excitatory postsynaptic potentials (fEPSPs) only atmore » the 30 ms inter-pulse interval. In addition, the induction of long-term potentiation (LTP) is impaired whereas the duration of long-term depression (LTD) becomes prolonged. Since both LTP and LTD depend critically on activation of NMDA and DA receptors, we also tested the effect of DA depletion on NMDA receptor-mediated synaptic transmission. Seven days after MPTP injection, the NMDA receptor-mediated fEPSPs are decreased by about 23%. Blocking the NMDA receptor-mediated fEPSP does not mimic the MPTP-LTP. Only co-application of D1/D5 and NMDA receptor antagonists during tetanization resembled the time course of fEPSP potentiation as observed 7 days after i.p. MPTP injection. Together, our data demonstrate that MPTP-induced degeneration of DA neurons and the subsequent hippocampal DA depletion alter NMDA receptor-mediated synaptic transmission and activity-dependent synaptic plasticity. - Highlights: > I.p. MPTP-injection mediates death of dopaminergic neurons. > I.p. MPTP-injection depletes DA and DOPAC in striatum and hippocampus. > I.p. MPTP-injection does not alter basal synaptic transmission. > Reduction of LTP and enhancement of LTD after i.p. MPTP-injection. > Attenuation of NMDA-receptors mediated fEPSPs after i.p. MPTP-injection.« less

[Nonuniform distribution and contribution of the P- and P/Q-type calcium channels to short-term inhibitory synaptic transmission in cultured hippocampal neurons].

PubMed

Mizerna, O P; Fedulova, S A; Veselovs'kyĭ, M S

2010-01-01

In the present study, we investigated the sensitivity of GABAergic short-term plasticity to the selective P- and P/Q-type calcium channels blocker omega-agatoxin-IVA. To block the P-type channels we used 30 nM of this toxin and 200 nM of the toxin was used to block the P/Q channel types. The evoked inhibitory postsynaptic currents (eIPSC) were studied using patch-clamp technique in whole-cell configuration in postsynaptic neuron and local extracellular stimulation of single presynaptic axon by rectangular pulse. The present data show that the contribution of P- and P/Q-types channels to GABAergic synaptic transmission in cultured hippocampal neurons are 30% and 45%, respectively. It was shown that the mediate contribution of the P- and P/Q-types channels to the amplitudes of eIPSC is different to every discovered neuron. It means that distribution of these channels is non-uniform. To study the short-term plasticity of inhibitory synaptic transmission, axons of presynaptic neurons were paired-pulse stimulated with the interpulse interval of 150 ms. Neurons demonstrated both the depression and facilitation. The application of 30 nM and 200 nM of the blocker decreased the depression and increased facilitation to 8% and 11%, respectively. In addition, we found that the mediate contribution of the P- and P/Q-types channels to realization of synaptic transmission after the second stimuli is 4% less compared to that after the first one. Therefore, blocking of both P- and P/Q-types calcium channels can change the efficiency of synaptic transmission. In this instance it facilitates realization of the transmission via decreased depression or increased facilitation. These results confirm that the P- and P/Q-types calcium channels are involved in regulation of the short-term inhibitory synaptic plasticity in cultured hippocampal neurons.

Effects of location and timing of co-activated neurons in the auditory midbrain on cortical activity: implications for a new central auditory prosthesis

NASA Astrophysics Data System (ADS)

Straka, Małgorzata M.; McMahon, Melissa; Markovitz, Craig D.; Lim, Hubert H.

2014-08-01

Objective. An increasing number of deaf individuals are being implanted with central auditory prostheses, but their performance has generally been poorer than for cochlear implant users. The goal of this study is to investigate stimulation strategies for improving hearing performance with a new auditory midbrain implant (AMI). Previous studies have shown that repeated electrical stimulation of a single site in each isofrequency lamina of the central nucleus of the inferior colliculus (ICC) causes strong suppressive effects in elicited responses within the primary auditory cortex (A1). Here we investigate if improved cortical activity can be achieved by co-activating neurons with different timing and locations across an ICC lamina and if this cortical activity varies across A1. Approach. We electrically stimulated two sites at different locations across an isofrequency ICC lamina using varying delays in ketamine-anesthetized guinea pigs. We recorded and analyzed spike activity and local field potentials across different layers and locations of A1. Results. Co-activating two sites within an isofrequency lamina with short inter-pulse intervals (<5 ms) could elicit cortical activity that is enhanced beyond a linear summation of activity elicited by the individual sites. A significantly greater extent of normalized cortical activity was observed for stimulation of the rostral-lateral region of an ICC lamina compared to the caudal-medial region. We did not identify any location trends across A1, but the most cortical enhancement was observed in supragranular layers, suggesting further integration of the stimuli through the cortical layers. Significance. The topographic organization identified by this study provides further evidence for the presence of functional zones across an ICC lamina with locations consistent with those identified by previous studies. Clinically, these results suggest that co-activating different neural populations in the rostral-lateral ICC rather than the caudal-medial ICC using the AMI may improve or elicit different types of hearing capabilities.

Influence of Pacing by Periodic Auditory Stimuli on Movement Continuation: Comparison with Self-regulated Periodic Movement

PubMed Central

Ito, Masanori; Kado, Naoki; Suzuki, Toshiaki; Ando, Hiroshi

2013-01-01

[Purpose] The purpose of this study was to investigate the influence of external pacing with periodic auditory stimuli on the control of periodic movement. [Subjects and Methods] Eighteen healthy subjects performed self-paced, synchronization-continuation, and syncopation-continuation tapping. Inter-onset intervals were 1,000, 2,000 and 5,000 ms. The variability of inter-tap intervals was compared between the different pacing conditions and between self-paced tapping and each continuation phase. [Results] There were no significant differences in the mean and standard deviation of the inter-tap interval between pacing conditions. For the 1,000 and 5,000 ms tasks, there were significant differences in the mean inter-tap interval following auditory pacing compared with self-pacing. For the 2,000 ms syncopation condition and 5,000 ms task, there were significant differences from self-pacing in the standard deviation of the inter-tap interval following auditory pacing. [Conclusion] These results suggest that the accuracy of periodic movement with intervals of 1,000 and 5,000 ms can be improved by the use of auditory pacing. However, the consistency of periodic movement is mainly dependent on the inherent skill of the individual; thus, improvement of consistency based on pacing is unlikely. PMID:24259932

Echolocating Big Brown Bats, Eptesicus fuscus, Modulate Pulse Intervals to Overcome Range Ambiguity in Cluttered Surroundings

PubMed Central

Wheeler, Alyssa R.; Fulton, Kara A.; Gaudette, Jason E.; Simmons, Ryan A.; Matsuo, Ikuo; Simmons, James A.

2016-01-01

Big brown bats (Eptesicus fuscus) emit trains of brief, wideband frequency-modulated (FM) echolocation sounds and use echoes of these sounds to orient, find insects, and guide flight through vegetation. They are observed to emit sounds that alternate between short and long inter-pulse intervals (IPIs), forming sonar sound groups. The occurrence of these strobe groups has been linked to flight in cluttered acoustic environments, but how exactly bats use sonar sound groups to orient and navigate is still a mystery. Here, the production of sound groups during clutter navigation was examined. Controlled flight experiments were conducted where the proximity of the nearest obstacles was systematically decreased while the extended scene was kept constant. Four bats flew along a corridor of varying widths (100, 70, and 40 cm) bounded by rows of vertically hanging plastic chains while in-flight echolocation calls were recorded. Bats shortened their IPIs for more rapid spatial sampling and also grouped their sounds more tightly when flying in narrower corridors. Bats emitted echolocation calls with progressively shorter IPIs over the course of a flight, and began their flights by emitting shorter starting IPI calls when clutter was denser. The percentage of sound groups containing 3 or more calls increased with increasing clutter proximity. Moreover, IPI sequences having internal structure become more pronounced when corridor width narrows. A novel metric for analyzing the temporal organization of sound sequences was developed, and the results indicate that the time interval between echolocation calls depends heavily on the preceding time interval. The occurrence of specific IPI patterns were dependent upon clutter, which suggests that sonar sound grouping may be an adaptive strategy for coping with pulse-echo ambiguity in cluttered surroundings. PMID:27445723

Xenon does not increase heart rate-corrected cardiac QT interval in volunteers and in patients free of cardiovascular disease.

PubMed

Neukirchen, Martin; Schaefer, Maximilian S; Kern, Carolin; Brett, Sarah; Werdehausen, Robert; Rellecke, Philipp; Reyle-Hahn, Matthias; Kienbaum, Peter

2015-09-01

Impaired cardiac repolarization, indicated by prolonged QT interval, may cause critical ventricular arrhythmias. Many anesthetics increase the QT interval by blockade of rapidly acting potassium rectifier channels. Although xenon does not affect these channels in isolated cardiomyocytes, the authors hypothesized that xenon increases the QT interval by direct and/or indirect sympathomimetic effects. Thus, the authors tested the hypothesis that xenon alters the heart rate-corrected cardiac QT (QTc) interval in anesthetic concentrations. The effect of xenon on the QTc interval was evaluated in eight healthy volunteers and in 35 patients undergoing abdominal or trauma surgery. The QTc interval was recorded on subjects in awake state, after their denitrogenation, and during xenon monoanesthesia (FetXe > 0.65). In patients, the QTc interval was recorded while awake, after anesthesia induction with propofol and remifentanil, and during steady state of xenon/remifentanil anesthesia (FetXe > 0.65). The QTc interval was determined from three consecutive cardiac intervals on electrocardiogram printouts in a blinded manner and corrected with Bazett formula. In healthy volunteers, xenon did not alter the QTc interval (mean difference: +0.11 ms [95% CI, -22.4 to 22.7]). In patients, after anesthesia induction with propofol/remifentanil, no alteration of QTc interval was noted. After propofol was replaced with xenon, the QTc interval remained unaffected (417 ± 32 ms vs. awake: 414 ± 25 ms) with a mean difference of 4.4 ms (95% CI, -4.6 to 13.5). Xenon monoanesthesia in healthy volunteers and xenon/remifentanil anesthesia in patients without clinically relevant cardiovascular disease do not increase QTc interval.

Dynamic QT Interval Changes from Supine to Standing in Healthy Children.

PubMed

Dionne, Audrey; Fournier, Anne; Dahdah, Nagib; Abrams, Dominic; Khairy, Paul; Abadir, Sylvia

2018-01-01

QT-interval variations in response to exercise-induced increases in heart rate have been reported in children and adults in the diagnosis of long QT syndrome (LQTS). A quick standing challenge has been proposed as an alternative provocative test in adults, with no pediatric data yet available. A standing test was performed in 100 healthy children (mean age, 9.7 ± 3.1 years) after 10 minutes in a supine position with continuous electrocardiographic recording. QT intervals were measured at baseline, at maximal heart rate, at maximal QT, and at each minute of a 5-minute recovery while standing. Measurements were taken in leads II/V 5 and were corrected for heart rate (QTc). On standing, the heart rate increased by 29 ± 10 beats per minute (bpm). The QT interval was similar at baseline and on standing (394 ± 34 ms vs 394 ± 34 ms; P = 1.0). However, QTc increased from 426 ± 21 to 509 ± 41 ms (P < 0.001). The 95th percentile for QTc at baseline and maximal heart rate was 457 ms and 563 ms, respectively. At 1 minute of recovery, the QT interval was shorter (375 ± 31 ms) compared with baseline (394 ± 34 ms; P < 0.001) and standing (394 ± 34 ms; P < 0.001). QTc reached baseline values after 1 minute of recovery and remained stable thereafter (423 ± 23 ms at 1 minute; 426 ± 22 ms at 5 minutes; P = 1.0). This first characterization of QTc changes on standing in children shows substantial alterations, which are greater than those seen in adults. Two-thirds of the children would have been misclassified as having LQTS by adult criteria, indicating the need to create child-specific standards. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Giant Pulses from PSR B1937+21 with Widths <=15 Nanoseconds and Tb>=5×1039 K, the Highest Brightness Temperature Observed in the Universe

NASA Astrophysics Data System (ADS)

Soglasnov, V. A.; Popov, M. V.; Bartel, N.; Cannon, W.; Novikov, A. Yu.; Kondratiev, V. I.; Altunin, V. I.

2004-11-01

Giant radio pulses of the millisecond pulsar B1937+21 were recorded with the S2 VLBI system at 1.65 GHz with NASA/JPL's 70 m radio telescope at Tidbinbilla, Australia. These pulses have been observed as strong as 65,000 Jy with widths <=15 ns, corresponding to a brightness temperature of Tb>=5×1039 K, the highest observed in the universe. The vast majority of these pulses occur in 5.8 and 8.2 μs windows at the very trailing edges of the regular main pulse and interpulse profiles, respectively. Giant pulses occur, in general, with a single spike. Only in one case of 309 was the structure clearly more complex. The cumulative distribution is fitted by a power law with index -1.40+/-0.01 with a low-energy but no high-energy cutoff. We estimate that giant pulses occur frequently but are only rarely detected. When corrected for the directivity factor, 25 giant pulses are estimated to be generated in one neutron star revolution alone. The intensities of the giant pulses of the main pulses and interpulses are not correlated with each other nor with the intensities or energies of the main pulses and interpulses themselves. Their radiation energy density can exceed 300 times the plasma energy density at the surface of the neutron star and can even exceed the magnetic field energy density at that surface. We therefore do not think that the generation of giant pulses is linked to the plasma mechanisms in the magnetosphere. Instead we suggest that it is directly related to discharges in the polar cap region of the pulsar.

Lacosamide cardiac safety: a thorough QT/QTc trial in healthy volunteers.

PubMed

Kropeit, D; Johnson, M; Cawello, W; Rudd, G D; Horstmann, R

2015-11-01

To determine whether lacosamide prolongs the corrected QT interval (QTc). In this randomized, double-blind, positive- and placebo-controlled, parallel-design trial, healthy volunteers were randomized to lacosamide 400 mg/day (maximum-recommended daily dose, 6 days), lacosamide 800 mg/day (supratherapeutic dose, 6 days), placebo (6 days), or moxifloxacin 400 mg/day (3 days). Variables included maximum time-matched change from baseline in QT interval individually corrected for heart rate ([HR] QTcI), other ECG parameters, pharmacokinetics (PK), and safety/tolerability. The QTcI mean maximum difference from placebo was -4.3 ms and -6.3 ms for lacosamide 400 and 800 mg/day; upper limits of the 2-sided 90% confidence interval were below the 10 ms non-inferiority margin (-0.5 and -2.5 ms, respectively). Placebo-corrected QTcI for moxifloxacin was +10.4 ms (lower 90% confidence bound >0 [6.6 ms]), which established assay sensitivity for this trial. As lacosamide did not increase QTcI, the trial is considered a negative QTc trial. There was no dose-related or clinically relevant effect on QRS duration. HR increased from baseline by ~5 bpm with lacosamide 800 mg/day versus placebo. Placebo-subtracted mean increases in PR interval at tmax were 7.3 ms (400 mg/day) and 11.9 ms (800 mg/day). There were no findings of second-degree or higher atrioventricular block. Adverse events (AEs) were dose related and most commonly involved the nervous and gastrointestinal systems. Lacosamide (≤ 800 mg/day) did not prolong the QTc interval. Lacosamide caused a small, dose-related increase in mean PR interval that was not associated with AEs. Cardiac, overall safety, and PK profiles for lacosamide in healthy volunteers were consistent with those observed in patients with partial-onset seizures. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Is there a prognostic relevance of electrophysiological studies in bundle branch block patients?

PubMed

Bogossian, Harilaos; Frommeyer, Gerrit; Göbbert, Kornelius; Hasan, Fuad; Nguyen, Quy Suu; Ninios, Ilias; Mijic, Dejan; Bandorski, Dirk; Hoeltgen, Reinhard; Seyfarth, Melchior; Lemke, Bernd; Eckardt, Lars; Zarse, Markus

2017-08-01

The present European guidelines suggest a diagnostic electrophysiological (EP) study to determine indication for cardiac pacing in patients with bundle branch block and unexplained syncope. We evaluated the prognostic relevance of an EP study for mortality and the development of permanent complete atrioventricular (AV) block in patients with symptomatic bifascicular block and first-degree AV block. The HV interval is a poor prognostic marker to predict the development of permanent AV block in patients with symptomatic bifascicular block (BFB) and AV block I°. Thirty consecutive patients (mean age, 74.8 ± 8.6 years; 25 males) with symptomatic BFB and first-degree AV block underwent an EP study before device implantation, according to current guidelines. For 53 ± 31 months, patients underwent yearly follow-up screening for syncope or higher-degree AV block. Thirty patients presented with prolonged HV interval during the EP study (mean, 82.2 ± 20.1 ms; range, 57-142 ms), classified into 3 groups: group 1, <70 ms (mean, 62 ± 4 ms; range, 57-67 ms; n = 7), group 2, >70 to ≤100 ms (mean, 80 ± 8 ms; range, 70-97 ms; n = 18), and group 3, >100 ms (mean, 119 ± 14 ms; range, 107-142 ms; n = 5). According to the guidelines, patients in groups 2 and 3 received a pacemaker. The length of the HV interval was not associated with the later development of third-degree AV block or with increased mortality. Our present study suggests that an indication for pacemaker implantation based solely on a diagnostic EP study with prolongation of the HV interval is not justified. © 2017 Wiley Periodicals, Inc.

Tp-Te interval predicts heart rate reduction after fingolimod administration in patients with multiple sclerosis.

PubMed

Tocci, Giuliano; Giuliani, Manuela; Canichella, Flaminia; Timpano, Jacopo; Presta, Vivianne; Francia, Pietro; Musumeci, Maria Beatrice; Fubelli, Federica; Pozzilli, Carlo; Volpe, Massimo; Ferrucci, Andrea

2016-10-15

FTY720 (Fingolimod) is an immunosuppressive drug, which provides favourable effects in patients with multiple sclerosis (MS), albeit it induces heart rate (HR) and blood pressure (BP) reductions. Therefore, we tested potential factors able to predict HR response in MS patients treated with fingolimod. We analysed patients with MS followed at our Neurology Outpatient Clinic from May 2013 to June 2015. All patients underwent BP measurements and 12-lead ECG before and 6-h after drug administration. At these time intervals, conventional and new ECG indexes for cardiac damage, including Tp-Te interval, were measured. Univariate and multivariate analyses were performed to test the outcome of HR reduction more than median difference between baseline and final observations. 69 outpatients with MS (46 males, age 35.1±9.4years, BP 119.0±12.7/73.0±9.3mmHg, HR 73.5±11.4bpm) were included. No relevant adverse reactions were reported. Fingolimod induced progressive systolic (P=0.024) and diastolic (P<0.001) BP, as well as HR (P<0.001) reductions compared to baseline. Prolonged PQ (150.4±19.5 vs. 157.0±19.5ms; P<0.001), QT (374.9±27.0 vs. 400.0±25.8ms; P<0.001), Tp-Te (1.8±0.3 vs. 1.9±0.3mm; P=0.021), and reduced QTc (414.4±24.4 vs. 404.5±24.5ms; P<0.001) intervals were also recorded at final observation. Baseline HR, QT and Tp-Te intervals provided prognostic information at univariate analysis, although Tp-Te interval resulted the best independent predictor for HR reduction at multivariate analysis [0.057 (0.005-0.660); P=0.022]. This study firstly demonstrates that prolonged Tp-Te interval may identify those MS patients treated with fingolimod at higher risk of having significant, asymptomatic HR reduction during clinical observation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Circadian rhythm in QT interval is preserved in mice deficient of potassium channel interacting protein 2.

PubMed

Gottlieb, Lisa A; Lubberding, Anniek; Larsen, Anders Peter; Thomsen, Morten B

2017-01-01

Potassium Channel Interacting Protein 2 (KChIP2) is suggested to be responsible for the circadian rhythm in repolarization duration, ventricular arrhythmias, and sudden cardiac death. We investigated the hypothesis that there is no circadian rhythm in QT interval in the absence of KChIP2. Implanted telemetric devices recorded electrocardiogram continuously for 5 days in conscious wild-type mice (WT, n = 9) and KChIP2 -/- mice (n = 9) in light:dark periods and in complete darkness. QT intervals were determined from all RR intervals and corrected for heart rate (QT 100 = QT/(RR/100) 1/2 ). Moreover, QT intervals were determined from complexes within the RR range of mean-RR ± 1% in the individual mouse (QT mean-RR ). We find that RR intervals are 125 ± 5 ms in WT and 123 ± 4 ms in KChIP2 -/- (p = 0.81), and QT intervals are 52 ± 1 and 52 ± 1 ms, respectively(p = 0.89). No ventricular arrhythmias or sudden cardiac deaths were observed. We find similar diurnal (light:dark) and circadian (darkness) rhythms of RR intervals in WT and KChIP2 -/- mice. Circadian rhythms in QT 100 intervals are present in both groups, but at physiological small amplitudes: 1.6 ± 0.2 and 1.0 ± 0.3 ms in WT and KChIP2 -/- , respectively (p = 0.15). A diurnal rhythm in QT 100 intervals was only found in WT mice. QT mean-RR intervals display clear diurnal and circadian rhythms in both WT and KChIP2 -/- . The amplitude of the circadian rhythm in QT mean-RR is 4.0 ± 0.3 and 3.1 ± 0.5 ms in WT and KChIP2 -/- , respectively (p = 0.16). In conclusion, KChIP2 expression does not appear to underlie the circadian rhythm in repolarization duration.

Association of low-moderate urine arsenic and QT interval: Cross-sectional and longitudinal evidence from the Strong Heart Study.

PubMed

Moon, Katherine A; Zhang, Yiyi; Guallar, Eliseo; Francesconi, Kevin A; Goessler, Walter; Umans, Jason G; Best, Lyle G; Howard, Barbara V; Devereux, Richard B; Okin, Peter M; Navas-Acien, Ana

2018-05-21

Epidemiologic studies suggest that chronic exposure to arsenic is related to cardiovascular disease (CVD), but the pathophysiological link remains uncertain. We evaluated the association of chronic low-moderate arsenic exposure and arsenic metabolism with baseline difference and annual change in ECG measures (QT interval, JT interval, PR interval, QRS duration, and QT dispersion) using linear mixed models in the Strong Heart Study main cohort (N = 1174, median age 55 years) and family study (N = 1695 diabetes-free, median age 36 years). At baseline, arsenic exposure was measured as the sum of inorganic and methylated species in urine (ΣAs) and arsenic metabolism was measured as the relative percentage of arsenic species. Median ΣAs and Bazett heart rate-corrected QT interval (QTc) were 8.6 μg/g creatinine and 424 ms in the main cohort and 4.3 μg/g and 414 ms in the family study, respectively. In the main cohort, a comparison of the highest to lowest ΣAs quartile (>14.4 vs. <5.2 μg/g creatinine) was associated with a 5.3 (95% CI: 1.2, 9.5) ms higher mean baseline QTc interval but no difference in annual change in QTc interval. In the family study, a comparison of the highest to lowest quartile (>7.1 vs. <2.9 μg/g creatinine) was associated with a 3.2 (95% CI: 0.6, 5.7) ms higher baseline QTc interval and a 0.6 (95% CI: 0.04, 1.2) ms larger annual increase in QTc interval. Associations with JTc interval were similar but stronger in magnitude compared to QTc interval. Arsenic exposure was largely not associated with PR interval, QRS duration or QT dispersion. Similar to arsenic exposure, a pattern of lower %MMA and higher %DMA was associated with longer baseline QTc interval in both cohorts and with a larger annual change in QTc interval in the family study. Chronic low-moderate arsenic exposure and arsenic metabolism were associated with prolonged ventricular repolarization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Formation of the stimulated electromagnetic emission spectra near gyroharmonics for quasi-stationary and decaying striations

NASA Astrophysics Data System (ADS)

Grach, Savely; Norin, Lars; Sergeev, Evgeny; Thide, Bo; Leyser, Thomas

We present new results of the analysis of the stimulated electromagnetic emission (SEE) measurements performed with special diagnostic HF-pumping scheme, for pump wave frequencies f0 close to a multiple of the electron gyroharmonic nfce , n = 4, 5. The pumping scheme used was an alternation of quasi-continuous pumping (˜ 100-200 ms on, ˜ 20-30 ms off) during a few tens of seconds, and low duty cycle radiation (pulse duration 20-500 ms with 1-3 s interpulse period). The main attention is paid to the following: (i) The development of some spectral features of the SEE, such as the downshifted maximum (DM), the second downshifted maximum (2DM), the upshifted maximum (UM) and the broad upshifted maximum (BUM) in a preconditioned ionosphere such that stationary small-scale magnetic field-aligned irregularities (striations) are already present. In particular, we characterize a fast (3-15 ms) overshoot in the DM, 2DM and UM, and we study the properties of a transient BUM with a maximum intensity for 18 kHz < f - f0 < 25 kHz and the same lower cutoff at f - f0 ≈ 14 kHz as the stationary BUM. The transient BUM vanishes after 5 to 10 ms of the pump turn-on and does not reappear. (ii) The formation of SEE features caused by the pump wave after the transition to low duty cycle pumping (i.e. on the background of decaying striations). In particular we note, that the BUM growths exponentially with a characteristic time ˜ 15 ms while the DM grows much faster and later exhibits slower dynamics. (iii) A slow (from pulse to pulse) temporal evolution of the SEE after the changing the pump scheme to a low duty cycle pulse mode. We note a disappearance of the transient BUM 1-2 s after the change of pump scheme and we observe an overshoot of the DM and (part of) the BUM. Higher frequency components of the BUM decays much faster than its lower frequencies. The results allow us to investigate ponderomotive processes responsible for the formation of upper hybrid turbulence in the HP-pumped ionosphere and the comparative contribution of the striations with different scales to the generation of different SEE spectral components. The work was supported by the RFBR (grants No. 06-02-17334, 07-02-00464).

Abnormalities of the QT interval in primary disorders of autonomic failure.

PubMed

Choy, A M; Lang, C C; Roden, D M; Robertson, D; Wood, A J; Robertson, R M; Biaggioni, I

1998-10-01

Experimental evidence shows that activation of the autonomic nervous system influences ventricular repolarization and, therefore, the QT interval on the ECG. To test the hypothesis that the QT interval is abnormal in autonomic dysfunction, we examined ECGs in patients with severe primary autonomic failure and in patients with congenital dopamine beta-hydroxylase (DbetaH) deficiency who are unable to synthesize norepinephrine and epinephrine. Maximal QT and rate-corrected QT (QTc) intervals and adjusted QTc dispersion [(maximal QTc - minimum QTc on 12 lead ECG)/square root of the number of leads measured] were determined in blinded fashion from ECGs of 67 patients with primary autonomic failure (36 patients with multiple system atrophy [MSA], and 31 patients with pure autonomic failure [PAF]) and 17 age- and sex-matched healthy controls. ECGs of 5 patients with congenital DbetaH deficiency and 6 age- and sex-matched controls were also analyzed. Patients with MSA and PAF had significantly prolonged maximum QTc intervals (492+/-58 ms(1/2) and 502+/-61 ms(1/2) [mean +/- SD]), respectively, compared with controls (450+/-18 ms(1/2), P < .05 and P < .01, respectively). A similar but not significant trend was observed for QT. QTc dispersion was also increased in MSA (40+/-20 ms(1/2), P < .05 vs controls) and PAF patients (32+/-19 ms(1/2), NS) compared with controls (21+/-5 ms(1/2)). In contrast, patients with congenital DbetaH deficiency did not have significantly different RR, QT, QTc intervals, or QTc dispersion when compared with controls. Patients with primary autonomic failure who have combined parasympathetic and sympathetic failure have abnormally prolonged QT interval and increased QT dispersion. However, QT interval in patients with congenital DbetaH deficiency was not significantly different from controls. It is possible, therefore, that QT abnormalities in patients with primary autonomic failure are not solely caused by lesions of the sympathetic nervous system, and that the parasympathetic nervous system is likely to have a modulatory role in ventricular repolarization.

Underestimated and unreported prolonged QTc by automated ECG analysis in patients on methadone: can we rely on computer reading?

PubMed

Talebi, Soheila; Azhir, Alaleh; Zuber, Sam; Soman, Sandeep; Visco, Ferdinand; Totouom-Tangho, Holly; Kalantar, Hossein; Worku Hassen, Getaw

2015-04-01

Recognition of prolonged corrected QT (QTc) interval is of particular importance, especially when using medications known to prolong QTc interval. Methadone can prolong the QTc interval and has the potential to induce torsades de pointes. The objective of this study is to investigate the accuracy of computerized ECG analysis in correctly identifying and reporting QTc interval in patients on methadone. We conducted a retrospective review of ECGs in the Muse electronic database of patients on methadone who are above 18 years old between January 2012 and December 2013 at an urban community hospital. ECGs were analyzed by the Marquette 12SL ECG Analysis Program (GE'Healthcare) reviewed by a cardiologist. A total of 826 ECGs of patients on methadone were examined manually for the QTc interval, of which 625 (75.7%) had QTc less than 470 ms, 149 (18%) had QTc between 470-499 ms and 52 (6.3%) had QTc more than 499 ms. QTc between 470-499 ms was underestimated by machine in 19 (12.8%) ECGs and QTc more than 499 ms was underestimated in 10 (19.6%) when compared to manually calculated QTc. QTc prolongation was underreported in 63 ECGs (48.5%) of those whose QTc between 470-499 ms and in 1 ECG (2.4%) of those whose QTc was more than 499 ms. QTc can be underestimated or unreported by the computer analysis. Physicians not only should calculate QTc manually but also examine the actual QTc value displayed on the report before concluding that this parameter is normal, especially in patients who are at risk of QTc prolongation.

Reinforcement and a cline in mating behaviour evolve in response to secondary contact and hybridization in shield-back katydids (Orthoptera: Tettigoniidae).

PubMed

Cole, J A

2016-09-01

In a dispersal-limited species that has evolved reproductive character displacement at a contact zone, a cline in mating behaviour may result if gene flow diffuses alleles out of the contact zone into allopatric populations. Prior work has found such a clinal pattern in the shield-back katydid Aglaothorax morsei, in which the male calling songs in a sympatric population have a displaced, short interpulse interval that increases in length with increasing distance from the contact zone. In this study, molecular phylogenetic and female preference data show that (1) sympatric populations result from secondary contact, (2) hybridization in sympatry has resulted in unidirectional mitochondrial introgression and (3) female preferences are consistent with reproductive character displacement and could generate a cline in mating behaviour. These data together suggest a history of reinforcement, generally considered rare in acoustically communicating insects; thus, Aglaothorax represents an important example of a rarely documented evolutionary process. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

A sEMG model with experimentally based simulation parameters.

PubMed

Wheeler, Katherine A; Shimada, Hiroshima; Kumar, Dinesh K; Arjunan, Sridhar P

2010-01-01

A differential, time-invariant, surface electromyogram (sEMG) model has been implemented. While it is based on existing EMG models, the novelty of this implementation is that it assigns more accurate distributions of variables to create realistic motor unit (MU) characteristics. Variables such as muscle fibre conduction velocity, jitter (the change in the interpulse interval between subsequent action potential firings) and motor unit size have been considered to follow normal distributions about an experimentally obtained mean. In addition, motor unit firing frequencies have been considered to have non-linear and type based distributions that are in accordance with experimental results. Motor unit recruitment thresholds have been considered to be related to the MU type. The model has been used to simulate single channel differential sEMG signals from voluntary, isometric contractions of the biceps brachii muscle. The model has been experimentally verified by conducting experiments on three subjects. Comparison between simulated signals and experimental recordings shows that the Root Mean Square (RMS) increases linearly with force in both cases. The simulated signals also show similar values and rates of change of RMS to the experimental signals.

Differential Effects of the Cannabinoid Agonist WIN55,212-2 on Delay and Trace Eyeblink Conditioning

PubMed Central

Steinmetz, Adam B.; Freeman, John H.

2014-01-01

Central cannabinoid-1 receptors (CB1R) play a role in the acquisition of delay eyeblink conditioning but not trace eyeblink conditioning in humans and animals. However, it is not clear why trace conditioning is immune to the effects of cannabinoid receptor compounds. The current study examined the effects of variants of delay and trace conditioning procedures to elucidate the factors that determine the effects of CB1R agonists on eyeblink conditioning. In Experiment 1 rats were administered the cannabinoid agonist WIN55,212-2 during delay, long delay, or trace conditioning. Rats were impaired during delay and long delay but not trace conditioning; the impairment was greater for long delay than delay conditioning. Trace conditioning was further examined in Experiment 2 by manipulating the trace interval and keeping constant the conditioned stimulus (CS) duration. It was found that when the trace interval was 300 ms or less WIN55,212-2 administration impaired the rate of learning. Experiment 3 tested whether the trace interval duration or the relative durations of the CS and trace interval were critical parameters influencing the effects of WIN55,212-2 on eyeblink conditioning. Rats were not impaired with a 100 ms CS, 200 ms trace paradigm but were impaired with a 1000 ms CS, 500 ms trace paradigm, indicating that the duration of the trace interval does not matter but the proportion of the interstimulus interval occupied by the CS relative to the trace period is critical. Taken together the results indicate that cannabinoid agonists affect cerebellar learning the CS is longer than the trace interval. PMID:24128358

Abnormalities of the QT interval in primary disorders of autonomic failure

NASA Technical Reports Server (NTRS)

Choy, A. M.; Lang, C. C.; Roden, D. M.; Robertson, D.; Wood, A. J.; Robertson, R. M.; Biaggioni, I.

1998-01-01

BACKGROUND: Experimental evidence shows that activation of the autonomic nervous system influences ventricular repolarization and, therefore, the QT interval on the ECG. To test the hypothesis that the QT interval is abnormal in autonomic dysfunction, we examined ECGs in patients with severe primary autonomic failure and in patients with congenital dopamine beta-hydroxylase (DbetaH) deficiency who are unable to synthesize norepinephrine and epinephrine. SUBJECTS AND METHODS: Maximal QT and rate-corrected QT (QTc) intervals and adjusted QTc dispersion [(maximal QTc - minimum QTc on 12 lead ECG)/square root of the number of leads measured] were determined in blinded fashion from ECGs of 67 patients with primary autonomic failure (36 patients with multiple system atrophy [MSA], and 31 patients with pure autonomic failure [PAF]) and 17 age- and sex-matched healthy controls. ECGs of 5 patients with congenital DbetaH deficiency and 6 age- and sex-matched controls were also analyzed. RESULTS: Patients with MSA and PAF had significantly prolonged maximum QTc intervals (492+/-58 ms(1/2) and 502+/-61 ms(1/2) [mean +/- SD]), respectively, compared with controls (450+/-18 ms(1/2), P < .05 and P < .01, respectively). A similar but not significant trend was observed for QT. QTc dispersion was also increased in MSA (40+/-20 ms(1/2), P < .05 vs controls) and PAF patients (32+/-19 ms(1/2), NS) compared with controls (21+/-5 ms(1/2)). In contrast, patients with congenital DbetaH deficiency did not have significantly different RR, QT, QTc intervals, or QTc dispersion when compared with controls. CONCLUSIONS: Patients with primary autonomic failure who have combined parasympathetic and sympathetic failure have abnormally prolonged QT interval and increased QT dispersion. However, QT interval in patients with congenital DbetaH deficiency was not significantly different from controls. It is possible, therefore, that QT abnormalities in patients with primary autonomic failure are not solely caused by lesions of the sympathetic nervous system, and that the parasympathetic nervous system is likely to have a modulatory role in ventricular repolarization.

Androgen profiling by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in healthy normal-weight ovulatory and anovulatory late adolescent and young women.

PubMed

Fanelli, Flaminia; Gambineri, Alessandra; Belluomo, Ilaria; Repaci, Andrea; Di Lallo, Valentina Diana; Di Dalmazi, Guido; Mezzullo, Marco; Prontera, Olga; Cuomo, Gaia; Zanotti, Laura; Paccapelo, Alexandro; Morselli-Labate, Antonio Maria; Pagotto, Uberto; Pasquali, Renato

2013-07-01

Physiological transient imbalance typical of adolescence needs to be distinguished from hyperandrogenism-related dysfunction. The accurate determination of circulating androgens is the best indicator of hyperandrogenism. However, reliable reference intervals for adolescent and young women are not available. The aim of the study was to define androgen reference intervals in young women and to analyze the impact of the menstrual phase and ovulation efficiency over the androgen profile as assessed by reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. Female high school students aged 16-19 years were included in the study. The study was performed on reference subjects properly selected among an unbiased population. Normal-weight, drug and disease free, eumenorrheic females with no signs of hyperandrogenism were included. The steroid hormone profile was determined by a validated in-house LC-MS/MS method. A statistical estimation of overall and menstrual phase-specific reference intervals was performed. A subgroup of anovulatory females was identified based on progesterone circulating levels. The impact of ovulation efficiency over hormonal profile was analyzed. A total of 159 females satisfied healthy criteria. Androgen levels did not vary according to menstrual phase, but a significantly higher upper reference limit was found for T in the luteal phase compared to the follicular phase. Higher T and androstenedione levels were observed in anovulatory compared to ovulatory females, paralleled by higher LH and FSH and lower 17-hydroxyprogesterone and 17β-estradiol levels. This is the first study providing LC-MS/MS-based, menstrual phase-specific reference intervals for the circulating androgen profile in young females. We identified a subgroup of anovulatory healthy females characterized by androgen imbalance.

77 FR 76456 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-28

... reach, x-ray beams with controllable polarization, and ``pump'' pulses over a vastly extended range of... project's ray probe pulses with controllable inter-pulse time delay. Justification for Duty-Free Entry... undergoes a metal to insulator transition when the LAO thickness is greater than 3 unit cells. The unique...

78 FR 5776 - University of Colorado Boulder, et al.; Notice of Consolidated Decision on Applications for Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-28

... capabilities of this instrument are expanded spectral reach, x-ray beams with controllable polarization, and... optical antennas, plasmonics in metals and semiconductors (including graphene), photonic crystals, and... the Linac Coherent Light Source II project's ray probe pulses with controllable inter-pulse time delay...

Influence of electron dynamics on the enhancement of double-pulse femtosecond laser-induced breakdown spectroscopy of fused silica

NASA Astrophysics Data System (ADS)

Cao, Zhitao; Jiang, Lan; Wang, Sumei; Wang, Mengmeng; Liu, Lei; Yang, Fan; Lu, Yongfeng

2018-03-01

Femtosecond laser pulse train induced breakdown of fused silica was studied by investigating its plasma emission and the ablated crater morphology. It was demonstrated that the electron dynamics in the ablated fused silica play a dominant role in the emission intensity of induced plasma and the volume of material removal, corresponding to the evolution of free-electron, self-trapped excitons, and the phase change of the fused silica left over by the first pulse. For a fluence of 11 J/cm2, the maximum plasma intensity of double-pulse irradiation at an interpulse delay of 120 ps was about 35 times stronger than that of a single-pulse, while the ablated crater was reduced by 27% in volume. The ionization of slow plume component generated by the first pulse was found to be the main reason for the extremely high intensity enhancement for an interpulse delay of over 10 ps. The results serve as a route to simultaneously increase the spatial resolution and plasma intensity in laser-induced breakdown spectroscopy of dielectrics.

Effect of posture on arterial baroreflex control of heart rate in humans

NASA Technical Reports Server (NTRS)

Harrison, M. H.; Rittenhouse, D.; Greenleaf, J. E.

1986-01-01

The effects of blood-volume redistribution induced by postural changes on baroreflex activity are investigated. The central blood volume and baroreceptor functions of ten males between 23-51 years old were examined while they were in the head-up tilt (HUT), head-down tilt (HDT), and supine positions. It is observed that during HDT at 15 deg the pulse interval over the first five cardiac cycles following neck suction onset is 51 + or - 18 ms longer, at 30 deg it is 61 + or - 20 ms longer, and at 45 deg it is 74 + or - 35 ms longer than at supine; during HUT at 15 deg the pulse interval is 25 + or - 9 ms shorter than when supine, but for the 30 and 45 deg there is no significant difference in pulse interval detected. The data reveal that posture does modify arterial baroreflex control of heart rate.

Multiple ECG Fiducial Points-Based Random Binary Sequence Generation for Securing Wireless Body Area Networks.

PubMed

Zheng, Guanglou; Fang, Gengfa; Shankaran, Rajan; Orgun, Mehmet A; Zhou, Jie; Qiao, Li; Saleem, Kashif

2017-05-01

Generating random binary sequences (BSes) is a fundamental requirement in cryptography. A BS is a sequence of N bits, and each bit has a value of 0 or 1. For securing sensors within wireless body area networks (WBANs), electrocardiogram (ECG)-based BS generation methods have been widely investigated in which interpulse intervals (IPIs) from each heartbeat cycle are processed to produce BSes. Using these IPI-based methods to generate a 128-bit BS in real time normally takes around half a minute. In order to improve the time efficiency of such methods, this paper presents an ECG multiple fiducial-points based binary sequence generation (MFBSG) algorithm. The technique of discrete wavelet transforms is employed to detect arrival time of these fiducial points, such as P, Q, R, S, and T peaks. Time intervals between them, including RR, RQ, RS, RP, and RT intervals, are then calculated based on this arrival time, and are used as ECG features to generate random BSes with low latency. According to our analysis on real ECG data, these ECG feature values exhibit the property of randomness and, thus, can be utilized to generate random BSes. Compared with the schemes that solely rely on IPIs to generate BSes, this MFBSG algorithm uses five feature values from one heart beat cycle, and can be up to five times faster than the solely IPI-based methods. So, it achieves a design goal of low latency. According to our analysis, the complexity of the algorithm is comparable to that of fast Fourier transforms. These randomly generated ECG BSes can be used as security keys for encryption or authentication in a WBAN system.

The effects of apremilast on the QTc interval in healthy male volunteers: a formal, thorough QT study

PubMed Central

Palmisano, Maria; Wu, Anfan; Assaf, Mahmoud; Liu, Liangang; Park, C. Hyung; Savant, Ishani; Liu, Yong; Zhou, Simon

2016-01-01

Objective: This study was conducted to evaluate the effect of apremilast and its major metabolites on the placebo-corrected change-from-baseline QTc interval of an electrocardiogram (ECG). Materials and methods: Healthy male subjects received each of 4 treatments in a randomized, crossover manner. In the 2 active treatment periods, apremilast 30 mg (therapeutic exposure) or 50 mg (supratherapeutic exposure) was administered twice daily for 9 doses. A placebo control was used to ensure double-blind treatment of apremilast, and an open-label, single dose of moxifloxacin 400 mg was administered as a positive control. ECGs were measured using 24-hour digital Holter monitoring. Results: The two-sided 98% confidence intervals (CIs) for ΔΔQTcI of moxifloxacin completely exceeded 5 ms 2 – 4 hours postdose. For both apremilast dose studies, the least-squares mean ΔΔQTcI was < 1 ms at all time points, and the upper limit of two-sided 90% CIs was < 10 ms. There were no QT/QTc values > 480 ms or a change from baseline > 60 ms. Exploratory evaluation of pharmacokinetic/pharmacodynamic data showed no trend between the changes in QT/QTc interval and the concentration of apremilast or its major metabolites M12 and M14. Conclusions: Apremilast did not prolong the QT interval and appears to be safe and well tolerated up to doses of 50 mg twice daily. PMID:27285466

Effect of intravenous amiodarone on QT and T peak-T end dispersions in patients with nonischemic heart failure treated with cardiac resynchronization-defibrillator therapy and electrical storm.

PubMed

Ogiso, Masataka; Suzuki, Atsushi; Shiga, Tsuyoshi; Nakai, Kenji; Shoda, Morio; Hagiwara, Nobuhisa

2015-02-01

The effect of intravenous amiodarone on spatial and transmural dispersion of ventricular repolarization in patients receiving cardiac resynchronization therapy (CRT) remains unclear. We studied 14 patients with nonischemic heart failure who received CRT with a defibrillator, experienced electrical storm and were treated with intravenous amiodarone. Each patient underwent 12-lead electrocardiography (ECG) and 187-channel repolarization interval-difference mapping electrocardiography (187-ch RIDM-ECG) before and during the intravenous administration of amiodarone infusion. A recurrence of ventricular tachyarrhythmia was observed in 2 patients during the early period of intravenous amiodarone therapy. Intravenous amiodarone increased the corrected QT interval (from 470±52 ms to 508±55 ms, P=0.003), but it significantly decreased the QT dispersion (from 107±35 ms to 49±27 ms, P=0.001), T peak-T end (Tp-e) dispersion (from 86±17 ms to 28±28 ms, P=0.001), and maximum inter-lead difference between corrected Tp-e intervals as measured by using the 187-ch RIDM-ECG (from 83±13 ms to 50±19 ms, P=0.001). Intravenous amiodarone suppressed the electrical storm and decreased the QT and Tp-e dispersions in patients treated by using CRT with a defibrillator.

Prevalence of the metabolic syndrome in a psychiatric hospital in Mexico.

PubMed

Díaz-Castro, Lina; Cabello-Rangel, Héctor; Cuevas-Pineda, Guillermo J; Reza-Garduño, Horacio; Castañeda-González, Carlos J

2011-01-01

The metabolic syndrome (MS) is formed by elevated blood pressure, hypercholesterolemia, hypertriglyceridemía, hyperglycemia and abdominal obesity. Mexico occupies the second place worldwide in prevalence of obesity. It has been reported that the use of psychopharmaceuticals increase the risk of MS. To detect prevalence of MS in patients with a psychiatric diagnosis with or without psychopharmaceutical treatment. An observational, descriptive study was designed. Informed consent was obtained, enrolling a sample of 216 patients in the six-month period, all of them over 18 years of age. The following variables were measured: blood pressure, weight, height, waist circumference, triglyceride, glucose and high-density lipoprotein serum levels, by colorimetric enzyme assay in Roche analyzer. Student's t-test, and Cochran-Mantel- Haenszel and Fisher's exact test. A total of 50% of the sample had a waist circumference >88 cm; 10% glycemia superior to 110 mg/dl, 30% triglycerides >150 mg/dl; 14% met the MS criteria. When patients with and without MS were grouped, and glucose and triglycerides were compared, a p 0.0001 was obtained. With a 93.4% confidence interval, the relationship between sedentary life and MS was accepted. Women, aged 40-59 years tended to have MS, with 98.4% CI. The only family background associated to MS was obesity (97.7% CI). There is a positive relationship between MS and the use of typical or atypical antipsychotics. SSRIs are significantly related with MS: p 0.072 and 91.5% confidence interval, benzodiazepines with p 0.073 and 92.7% confidence interval. Only 14% of the sample had MS. Psychopharmaceuticals were associated to MS, women between 40 to 59 years having a greater risk.

Associative spike timing-dependent potentiation of the basal dendritic excitatory synapses in the hippocampus in vivo.

PubMed

Fung, Thomas K; Law, Clayton S; Leung, L Stan

2016-06-01

Spike timing-dependent plasticity in the hippocampus has rarely been studied in vivo. Using extracellular potential and current source density analysis in urethane-anesthetized adult rats, we studied synaptic plasticity at the basal dendritic excitatory synapse in CA1 after excitation-spike (ES) pairing; E was a weak basal dendritic excitation evoked by stratum oriens stimulation, and S was a population spike evoked by stratum radiatum apical dendritic excitation. We hypothesize that positive ES pairing-generating synaptic excitation before a spike-results in long-term potentiation (LTP) while negative ES pairing results in long-term depression (LTD). Pairing (50 pairs at 5 Hz) at ES intervals of -10 to 0 ms resulted in significant input-specific LTP of the basal dendritic excitatory sink, lasting 60-120 min. Pairing at +10- to +20-ms ES intervals, or unpaired 5-Hz stimulation, did not induce significant basal dendritic or apical dendritic LTP or LTD. No basal dendritic LTD was found after stimulation of stratum oriens with 200 pairs of high-intensity pulses at 25-ms interval. Pairing-induced LTP was abolished by pretreatment with an N-methyl-d-aspartate receptor antagonist, 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), which also reduced spike bursting during 5-Hz pairing. Pairing at 0.5 Hz did not induce spike bursts or basal dendritic LTP. In conclusion, ES pairing at 5 Hz resulted in input-specific basal dendritic LTP at ES intervals of -10 ms to 0 ms but no LTD at ES intervals of -20 to +20 ms. Associative LTP likely occurred because of theta-rhythmic coincidence of subthreshold excitation with a backpropagated spike burst, which are conditions that can occur naturally in the hippocampus. Copyright © 2016 the American Physiological Society.

Associative spike timing-dependent potentiation of the basal dendritic excitatory synapses in the hippocampus in vivo

PubMed Central

Fung, Thomas K.; Law, Clayton S.

2016-01-01

Spike timing-dependent plasticity in the hippocampus has rarely been studied in vivo. Using extracellular potential and current source density analysis in urethane-anesthetized adult rats, we studied synaptic plasticity at the basal dendritic excitatory synapse in CA1 after excitation-spike (ES) pairing; E was a weak basal dendritic excitation evoked by stratum oriens stimulation, and S was a population spike evoked by stratum radiatum apical dendritic excitation. We hypothesize that positive ES pairing—generating synaptic excitation before a spike—results in long-term potentiation (LTP) while negative ES pairing results in long-term depression (LTD). Pairing (50 pairs at 5 Hz) at ES intervals of −10 to 0 ms resulted in significant input-specific LTP of the basal dendritic excitatory sink, lasting 60–120 min. Pairing at +10- to +20-ms ES intervals, or unpaired 5-Hz stimulation, did not induce significant basal dendritic or apical dendritic LTP or LTD. No basal dendritic LTD was found after stimulation of stratum oriens with 200 pairs of high-intensity pulses at 25-ms interval. Pairing-induced LTP was abolished by pretreatment with an N-methyl-d-aspartate receptor antagonist, 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), which also reduced spike bursting during 5-Hz pairing. Pairing at 0.5 Hz did not induce spike bursts or basal dendritic LTP. In conclusion, ES pairing at 5 Hz resulted in input-specific basal dendritic LTP at ES intervals of −10 ms to 0 ms but no LTD at ES intervals of −20 to +20 ms. Associative LTP likely occurred because of theta-rhythmic coincidence of subthreshold excitation with a backpropagated spike burst, which are conditions that can occur naturally in the hippocampus. PMID:27052581

Prevalence of QT interval prolongation in patients admitted to cardiac care units and frequency of subsequent administration of QT interval-prolonging drugs: a prospective, observational study in a large urban academic medical center in the US.

PubMed

Tisdale, James E; Wroblewski, Heather A; Overholser, Brian R; Kingery, Joanna R; Trujillo, Tate N; Kovacs, Richard J

2012-06-01

Cardiac arrest due to torsades de pointes (TdP) is a rare but catastrophic event in hospitals. Patients admitted to cardiac units are at higher risk of drug-induced QT interval prolongation and TdP, due to a preponderance of risk factors. Few data exist regarding the prevalence of QT interval prolongation in patients admitted to cardiac units or the frequency of administering QT interval-prolonging drugs to patients presenting with QT interval prolongation. The aim of this study was to determine the prevalence of Bazett's-corrected QT (QT(c)) interval prolongation upon admission to cardiac units and the proportion of patients presenting with QT(c) interval prolongation who are subsequently administered QT interval-prolonging drugs during hospitalization. This was a prospective, observational study conducted over a 1-year period (October 2008-October 2009) in 1159 consecutive patients admitted to two cardiac units in a large urban academic medical centre located in Indianapolis, IN, USA. Patients were enrolled into the study at the time of admission to the hospital and were followed daily during hospitalization. Exclusion criteria were age <18 years, ECG rhythm of complete ventricular pacing, and patient designation as 'outpatient' in a bed and/or duration of stay <24 hours. Data collected included demographic information, past medical history, daily progress notes, medication administration records, laboratory data, ECGs, telemetry monitoring strips and diagnostic reports. All patients underwent continuous cardiac telemetry monitoring and/or had a baseline 12-lead ECG obtained within 4 hours of admission. QT intervals were determined manually from lead II of 12-lead ECGs or from continuous lead II telemetry monitoring strips. QT(c) interval prolongation was defined as ≥470 ms for males and ≥480 ms for females. In both males and females, QT(c) interval >500 ms was considered abnormally high. A medication was classified as QT interval-prolonging if there were published data indicating that the drug causes QT interval prolongation and/or TdP. Study endpoints were (i) prevalence of QT(c) interval prolongation upon admission to the Cardiac Medical Critical Care Unit (CMCCU) or an Advanced Heart Care Unit (AHCU); (ii) proportion of patients admitted to the CMCCU/AHCU with QT(c) interval prolongation who subsequently were administered QT interval-prolonging drugs during hospitalization; (iii) the proportion of these higher-risk patients in whom TdP risk factor monitoring was performed; (iv) proportion of patients with QT(c) interval prolongation who subsequently received QT-prolonging drugs and who experienced further QT(c) interval prolongation. Of 1159 patients enrolled, 259 patients met exclusion criteria, resulting in a final sample size of 900 patients. mean (± SD) age, 65 ± 15 years; female, 47%; Caucasian, 70%. Admitting diagnoses: heart failure (22%), myocardial infarction (16%), atrial fibrillation (9%), sudden cardiac arrest (3%). QT(c) interval prolongation was present in 27.9% of patients on admission; 18.2% had QT(c) interval >500 ms. Of 251 patients admitted with QT(c) interval prolongation, 87 (34.7%) were subsequently administered QT interval-prolonging drugs. Of 166 patients admitted with QT(c) interval >500 ms, 70 (42.2%) were subsequently administered QT interval-prolonging drugs; additional QT(c) interval prolongation ≥60 ms occurred in 57.1% of these patients. QT(c) interval prolongation is common among patients admitted to cardiac units. QT interval-prolonging drugs are commonly prescribed to patients presenting with QT(c) interval prolongation.

Validation of PR interval length as a criterion for development of atrial fibrillation in non-Hispanic whites, African Americans and Hispanics.

PubMed

Shulman, Eric; Aagaard, Philip; Kargoli, Faraj; Hoch, Ethan; Zheng, Laura; Di Biase, Luigi; Fisher, John; Gross, Jay; Kim, Soo; Ferrick, Kevin; Krumerman, Andrew

2015-01-01

PR interval prolongation on electrocardiogram (ECG) increases the risk of atrial fibrillation (AF). Non-Hispanic Whites are at higher risk of AF compared to African Americans and Hispanics. However, it remains unknown if prolongation of the PR interval for the development of AF varies by race/ethnicity. Therefore, we determined whether race affects the PR interval length's ability to predict AF and if the commonly used criterion of 200 ms in AF prediction models can continue to be used for non-White cohorts. This is a retrospective epidemiological study of consecutive inpatient and outpatients. An ECG database was initially interrogated. Patients were included if their initial ECG demonstrated sinus rhythm and had two or more electrocardiograms and declared a race and/or ethnicity as non-Hispanic White, African American or Hispanic. Development of AF was stratified by race/ethnicity along varying PR intervals. Cox models controlled for age, gender, race/ethnicity, systolic blood pressure, BMI, QRS, QTc, heart rate, murmur, treatment for hypertension, heart failure and use of AV nodal blocking agents to assess PR interval's predictive ability for development of AF. 50,870 patients met inclusion criteria of which 5,199 developed AF over 3.72 mean years of follow-up. When the PR interval was separated by quantile, prolongation of the PR interval to predict AF first became significant in Hispanic and African Americans at the 92.5th quantile of 196-201 ms (HR: 1.42, 95% CI: 1.09-1.86, p=0.01; HR: 1.32, 95% CI: 1.07-1.64, p=0.01, respectively) then in non-Hispanic Whites at the 95th quantile at 203-212 ms (HR: 1.24, 95% CI: 1.24-1.53, p=0.04). For those with a PR interval above 200 ms, African Americans had a lower risk than non-Hispanic Whites to develop AF (HR: 0.80, 95% CI: 0.64-0.95, p=0.012), however, no significant difference was demonstrated in Hispanics. This is the first study to validate a PR interval value of 200 ms as a criterion in African Americans and Hispanics for the development of AF. However, a value of 200 ms may be less sensitive as a predictive measure for the development of AF in African Americans compared to non-Hispanic Whites. Copyright © 2015 Elsevier Inc. All rights reserved.

Atrial electromechanical coupling intervals in pregnant subjects.

PubMed

Altun, Burak; Tasolar, Hakan; Gazï, Emïne; Gungor, Aysenur Cakir; Uysal, Ahmet; Temïz, Ahmet; Barutcu, Ahmet; Acar, Gurkan; Colkesen, Yucel; Ozturk, Ufuk; Akkoy, Murat

2014-01-01

The aim of this study was to evaluate atrial conduction abnormalities obtained by tissue Doppler imaging (TDI) and electrocardiogram analysis in pregnant subjects. A total of 30 pregnant subjects (28 ± 4 years) and 30 controls (28 ± 3 years) were included. Systolic and diastolic left ventricular (LV) function was measured using conventional echocardiography and TDI. Inter-atrial, intraatrial and intra-left atrial electromechanical coupling (PA) intervals were measured with TDI. P-wave dispersion (PD) was calculated from a 12-lead electrocardiogram. Atrial electromechanical coupling at the septal and left lateral mitral annulus (PA septal, PA lateral) was significantly prolonged in pregnant subjects (62.1 ± 2.7 vs 55.3 ±3.2 ms, p < 0.001; 45.7 ± 2.5 vs 43.1 ± 2.7 ms, p < 0.001, respectively). Inter-atrial (PA lateral - PA tricuspid), intra-atrial (PA septum - PA tricuspid) and intra-left atrial (PA lateral - PA septum) electromechanical coupling intervals, maximum P-wave (Pmax) duration and PD were significantly longer in the pregnant subjects (26.4 ± 4.0 vs 20.2 ± 3.6 ms, p < 0.001; 10.0 ± 2.0 vs 8.0 ± 2.6 ms, p = 0.002; 16.4 ± 3.3 vs 12.2 ± 3.0 ms, p < 0.001; 103.1 ± 5.4 vs 96.8 ± 7.4 ms, p ± 0.001; 50.7 ± 6.8 vs 41.6 ± 5.5 ms, p < 0.001, respectively). We found a significant positive correlation between inter-atrial and intraleft atrial electromechanical coupling intervals and Pmax (r = 0.282, p = 0.029, r = 0.378, p = 0.003, respectively). This study showed that atrial electromechanical coupling intervals and PD, which are predictors of AF, were longer in pregnant subjects and this may cause an increased risk of AF in pregnancy.

Abnormal myocardial repolarisation in response to hypoxaemia and fenoterol.

PubMed Central

Kiely, D. G.; Cargill, R. I.; Grove, A.; Struthers, A. D.; Lipworth, B. J.

1995-01-01

BACKGROUND--Prolongation of the QTc interval has been associated with cardiac dysrhythmias and sudden death. QTc dispersion (interlead variability in QTc interval) has recently been proposed as being a more sensitive marker of repolarisation abnormalities and shown to be a more specific index of arrhythmia risk. Although hypoxaemia and fenoterol have previously been shown to prolong the QTc interval, this does not reflect regional myocardial repolarisation abnormalities. METHODS--Electrophysiological effects were measured at baseline and after 30 minutes steady state hypoxaemia at an arterial oxygen saturation (SaO2) of 75-80% (study 1) and at baseline then 30 minutes after inhaled fenoterol 2.4 mg (study 2). From the ECG, lead II corrected QT interval (QTc) and overall corrected QT dispersion were measured using a computer linked digitising tablet according to standard criteria. RESULTS--QTc dispersion was increased during hypoxia compared with baseline values (mean (SE) 69 (6) ms v 50 (5) ms) and after fenoterol compared with baseline (79 (13) v 46 (4) ms), respectively. There was also an increase in QTc interval and heart rate after fenoterol (493 (23) v 420 (6) ms and 98 (3) v 71 (6) bpm, respectively). The heart rate was increased during hypoxaemia compared with baseline (78 (3) v 64 (2) bpm), but no change occurred in the QTc interval. CONCLUSIONS--Both hypoxaemia and fenoterol cause myocardial repolarisation abnormalities in man in terms of increased QTc dispersion, but only fenoterol increased the QTc interval. This may be relevant in the aetiology of arrhythmias in patients with acute severe asthma where beta agonist therapy and hypoxaemia coexist. PMID:7491554

The optimized V-V interval determined by interventricular conduction times versus invasive measurement by LVdP/dtMAX.

PubMed

van Gelder, Berry M; Meijer, Albert; Bracke, Frank A

2008-09-01

We compared the calculated optimal V-V interval derived from intracardiac electrograms (IEGM) with the optimized V-V interval determined by invasive measurement of LVdP/dt(MAX). Thirty-two patients with heart failure (six females, ages 68 +/- 7.8 years) had a CRT device implanted. After implantation of the atrial, right and a left ventricular lead, the optimal V-V interval was calculated using the QuickOpt formula (St. Jude Medical, Sylmar, CA, USA) applied to the respective IEGM recordings (V-V(IEGM)), and also determined by invasive measurement of LVdP/dt(MAX) (V-V(dP/dt)). The optimal V-V(IEGM) and V-V(dP/dt) intervals were 52.7 +/- 18 ms and 24.0 +/- 33 ms, respectively (P = 0.017), without correlation between the two. The baseline LVdP/dt(MAX) was 748 +/- 191 mmHg/s. The mean value of LVdP/dt(MAX) at invasive optimization was 947 +/- 198 mmHg/s, and at the calculated optimal V-V(IEGM) interval 920 +/- 191 mmHg/s (P < 0.0001). In spite of this significant difference, there was a good correlation between both methods (R = 0.991, P < 0.0001). However, a similarly good correlation existed between the maximum value of LVdP/dt(MAX) and LVdP/dt(MAX) at a fixed V-V interval of 0 ms (R = 0.993, P < 0.0001), or LVdP/dt(MAX) at a randomly selected V-V interval between 0 and +80 ms (R = 0.991, P < 0.0001). Optimizing the V-V interval with the IEGM method does not yield better hemodynamic results than simultaneous BiV pacing. Although a good correlation between LVdP/dt(MAX) determined with V-V(IEGM) and V-V(dP/dt) can be constructed, there is no correlation with the optimal settings of V-V interval in the individual patient.

Prolonged corrected QT interval is predictive of future stroke events even in subjects without ECG-diagnosed left ventricular hypertrophy.

PubMed

Ishikawa, Joji; Ishikawa, Shizukiyo; Kario, Kazuomi

2015-03-01

We attempted to evaluate whether subjects who exhibit prolonged corrected QT (QTc) interval (≥440 ms in men and ≥460 ms in women) on ECG, with and without ECG-diagnosed left ventricular hypertrophy (ECG-LVH; Cornell product, ≥244 mV×ms), are at increased risk of stroke. Among the 10 643 subjects, there were a total of 375 stroke events during the follow-up period (128.7±28.1 months; 114 142 person-years). The subjects with prolonged QTc interval (hazard ratio, 2.13; 95% confidence interval, 1.22-3.73) had an increased risk of stroke even after adjustment for ECG-LVH (hazard ratio, 1.71; 95% confidence interval, 1.22-2.40). When we stratified the subjects into those with neither a prolonged QTc interval nor ECG-LVH, those with a prolonged QTc interval but without ECG-LVH, and those with ECG-LVH, multivariate-adjusted Cox proportional hazards analysis demonstrated that the subjects with prolonged QTc intervals but not ECG-LVH (1.2% of all subjects; incidence, 10.7%; hazard ratio, 2.70, 95% confidence interval, 1.48-4.94) and those with ECG-LVH (incidence, 7.9%; hazard ratio, 1.83; 95% confidence interval, 1.31-2.57) had an increased risk of stroke events, compared with those with neither a prolonged QTc interval nor ECG-LVH. In conclusion, prolonged QTc interval was associated with stroke risk even among patients without ECG-LVH in the general population. © 2014 American Heart Association, Inc.

Acousto-Optical Vector Matrix Product Processor: Implementation Issues

DTIC Science & Technology

1989-04-25

power by a factor of 3.8. The acoustic velocity in longitudinal TeO2 is 4200 m/s, almost the same as the 4100 m/s acoustic velocity in dense flint glass ...field via an Interaction Model AOD150 dense flint glass Bragg Cell. The cell’s specifications are listed in the table below. BRAGG CELL SPECIFICATIONS...39 ns intervals). Since the speed of sound in dense flint glass is 4100 m/s, the acoustic field generated in a 10 As interval is distributed over a 4.1

QTc abnormalities in deliberate self-poisoning with moclobemide.

PubMed

Downes, M A; Whyte, I M; Isbister, G K

2005-07-01

Several medications have been found to prolong the QT interval in overdose. This can predispose to torsade de pointes-type ventricular tachycardia. To analyse the effects of moclobemide deliberate self-poisoning on the length of both QT and corrected QT (QTc) intervals. Electrocardiograms (ECG) of all patients presenting to a regional toxicology service with moclobemide ingestion were reviewed. Cases where a cardiotoxic agent was coingested were excluded. QT and QTc parameters were compared with a comparison group of patients ingesting paracetamol or benzodiazepines. Of 75 patients where ECG were available, the median ingested dose was 4.5 g (interquartile range (IQR): 2.4-7.5; range: 0.6-18 g) and the median age was 34 years (IQR: 26-44). The mean QT interval was 415 ms (standard deviation (SD): 51 ms) with a mean QTc of 459 ms (SD: 44 ms), and were prolonged compared with the comparison group. Twelve female patients had a QTc > 500 ms and in seven of these causality was established based on a pre- or post-ECG with a QTc < 500 ms. Only 10% of the moclobemide cases had a heart rate (HR) > 100 beats per minute, making overcorrection of HR by Bazett's formula an unlikely cause of the findings. No cardiac arrythmias were observed other than one case of first-degree heart block. Moclobemide prolongs the QT and QTc intervals in overdose and a 12-lead ECG should be done on all moclobemide deliberate self-poisonings. Continuous cardiac monitoring for what is otherwise a relatively benign overdose would appear to be an inappropriate use of resources but can be considered in patients with a QTc > 500 ms or with known risks for QT prolongation.

Effect of hyperventilation on rate corrected QT interval of children.

PubMed

Kannivelu, Arivalagan; Kudumula, Vikram; Bhole, Vinay

2013-02-01

Hyperventilation is known to cause ST segment changes and QT variability in adults, but this has not been systematically studied in children. To investigate the effect of hyperventilation on rate corrected QT interval (QTc) in children. 25 children (male=10) with a median age of 14 (range 8.3-17.6) years were asked to hyperventilate for 1 min before exercise testing using the modified Bruce protocol. Mean QTc at rest, after hyperventilation, at peak exercise and at 1 min of recovery was 425(±31), 460(±30), 446(±38) and 420(±32) ms, respectively. Mean increase (95% CI) in QTc after hyperventilation was 35(19 to 51) ms (p<0.001), while there was minimal difference between QT interval at rest and after hyperventilation (mean QT 352(±41) vs 357(±44) ms). In six children, there were abnormalities in T wave morphology following hyperventilation. The QTc increment following hyperventilation was more pronounced in children with resting QTc <440 ms (n=14, mean increment (95% CI): 55 (33 to 78) ms) compared to children with QTc ≥440 ms (n=11, mean increment (95% CI): 9 (-4 to 22) ms) (p=0.001). QTc prolongation following hyperventilation was seen in children with both low and intermediate probability of long QT syndrome (LQTS). Peak exercise and early recovery did not cause a statistically significant change in QTc in either of these groups. Hyperventilation produces repolarisation abnormalities, including prolongation of QTc and T wave abnormalities in children with low probability of LQTS. The likely mechanism is delayed adaptation of QT interval with increased heart rate. Thus, a hyperventilation episode can be misdiagnosed as LQTS, especially in an emergency department.

[Structure of maxillary sinus mucous membrane under normal conditions and in odontogenic perforative sinusitis].

PubMed

Baĭdik, O D; Logvinov, S V; Zubarev, S G; Sysoliatin, P G; Gurin, A A

2011-01-01

Methods of light, electron microscopy and immunohistochemistry were used to study the samples of maxillary sinus (MS) mucous membrane (MM) under normal conditions and in odontogenic sinusitis. To study the normal structure, the samples were obtained at autopsy from 26 human corpses 12-24 hours after death. Electron microscopic and immunohistochemical study was performed on biopsies of grossly morphologically unchanged MS MM, obtained during the operations for retention cysts in 6 patients. MS MM in perforative sinusitis was studied using the biopsies obtained from 43 patients. The material is broken into 4 groups depending on perforative sinusitis duration. Under normal conditions, MS MM is lined with a pseudostratified columnar ciliated epithelium. Degenerative changes of ciliated epithelial cells were already detected at short time intervals after MS perforations and become apparent due to reduction of specific volume of mitochondria and, rough endoplasmic reticulum, and increase of nuclear-cytoplasmic ratio. In the globlet cells, the reduction of nuclear-cytoplasmic ratio was associated with the disturbance of the secretory product release. At time intervals exceeding 3 months, epithelium underwent metaplasia into simple cuboidal and stratified squamous keratinized, while in MS MM lamina propria, cellular infiltration was increased. CD4+ cell content in sinus MM gradually increased, while at late periods after perforation occurrence it decreased. Low CD4+ cell count within the epithelium and the absence of muromidase on the surface of MS MM was detected. With the increase of the time interval since MS perforation, the number of CD8+ and CD20+ cells in MS MM was found to increase.

Drug-Induced QTc Interval Prolongation: A Multicenter Study to Detect Drugs and Clinical Factors Involved in Every Day Practice.

PubMed

Keller, Guillermo A; Alvarez, Paulino A; Ponte, Marcelo L; Belloso, Waldo H; Bagnes, Claudia; Sparanochia, Cecilia; Gonzalez, Claudio D; Villa Etchegoyen, M Cecilia; Diez, Roberto A; Di Girolamo, Guillermo

2016-01-01

The actual prevalence of drug induced QTc prolongation in clinical practice is unknown. Our objective was to determine the occurrence and characteristics of drug-induced QT prolongation in several common clinical practices. Additionally, a subgroup of patients treated with dextropropoxyphene of particular interest for the regulatory authority was analysed. Medical history and comorbidities predisposing to QT interval prolongation were registered for 1270 patient requiring medical assistance that involved drug administration. Three ionograms and ECGs were performed: baseline, intra- and after treatment; QT interval was corrected with Bazzet formula. Among patients, 9.9% presented QTc >450/470 ms, 3% QTc > 500 ms, 12.7% ΔQTc >30 ms and 5.2% ΔQTc >60 ms. QTc prolongation associated with congestive heart failure, ischemic cardiopathy, diabetes, renal failure, arrhythmias, hypothyroidism, and bradycardia. At univariate analysis, clarithromycin, haloperidol, tramadol, amiodarone, glyceryl trinitrate, amoxicillin + clavulanic acid, amoxicillin + sulbactam, ampicillin + sulbactam, fentanyl, piperacillin + tazobactam, and diazepam prolonged QTc. Prolongation remained significantly associated with furosemide, clarithromycin, glyceryl trinitrate and betalactamase inhibitors after multivariate analysis. QT interval prolongation in everyday practice is frequent, in association to clinical factors and drugs that can be easily identified for monitoring and prevention strategies.

Type 1 diabetes and multiple sclerosis: A Danish population-based cohort study.

PubMed

Nielsen, Nete M; Westergaard, Tine; Frisch, Morten; Rostgaard, Klaus; Wohlfahrt, Jan; Koch-Henriksen, Nils; Melbye, Mads; Hjalgrim, Henrik

2006-07-01

Type 1 diabetes mellitus (T1D) and multiple sclerosis (MS) contribute considerably to the burden of autoimmune diseases in young adults. Although HLA patterns of T1D and MS are considered mutually exclusive, individual and familial co-occurrence of the 2 diseases has been reported. To assess the co-occurrence of T1D and MS by estimating the risk for MS in patients with T1D and the risk for T1D in first-degree relatives of patients with MS. Two population-based disease registers, the Danish Hospital Discharge Register and the Danish Multiple Sclerosis Register were used to identify patients with T1D, defined as patients in whom diabetes was diagnosed before age 20 years (N = 6078), and patients with MS (N = 11 862). First-degree relatives (N = 14,771) of patients with MS were identified from family information in the Danish Civil Registration System. Patients with T1D and first-degree relatives of patients with MS were followed up for occurrence of MS and T1D, respectively, and the relative risks were expressed as standardized incidence ratios, that is, ratios of observed to expected numbers of outcomes based on national age, sex, and period-specific MS and T1D incidence rates. Patients with T1D were at more than 3-fold increased risk for development of MS (relative risk, 3.26; 95% confidence interval, 1.80-5.88; n = 11). First-degree relatives of patients with MS were at 63% increased risk (relative risk, 1.63; 95% confidence interval, 1.26-2.12; n = 56) for development of T1D. However, adjusting for familial relationship to patients with T1D reduced the excess risk to 44% (relative risk, 1.44; 95% confidence interval, 1.11-1.88; n = 56). The present nationwide cohort study demonstrates an intraindividual and, to a lesser degree, an intrafamilial co-occurrence of MS and T1D.

Evaluation of inhomogeneities of repolarization in patients with psoriasis vulgaris

PubMed Central

İnci, Sinan; Aksan, Gökhan; Nar, Gökay; Yüksel, Esra Pancar; Ocal, Hande Serra; Çapraz, Mustafa; Yüksel, Serkan; Şahin, Mahmut

2016-01-01

Introduction The arrhythmia potential has not been investigated adequately in psoriatic patients. In this study, we assessed the ventricular repolarization dispersion, using the Tp-e interval and the Tp-e/QT ratio, and investigated the association with inflammation. Material and methods Seventy-one psoriasis vulgaris patients and 70 age- and gender-matched healthy individuals were enrolled in the study. The severity of the disease was calculated using Psoriasis Area and Severity Index scoring. The QTd was defined as the difference between the maximum and minimum QT intervals. The Tp-e interval was defined as the interval from the peak of the T wave to the end of the T wave. The Tp-e interval was corrected for heart rate. The Tp-e/QT ratio was calculated using these measurements. Results There were no significant differences between the groups with respect to basal clinical and laboratory characteristics (p > 0.05). The Tp-e interval, the corrected Tp-e interval (cTp-e) and the Tp-e/QT ratio were also significantly higher in psoriasis patients compared to the control group (78.5 ±8.0 ms vs. 71.4 ±7.6 ms, p < 0.001, 86.3 ±13.2 ms vs. 77.6 ±9.0 ms, p < 0.001 and 0.21 ±0.02 vs. 0.19 ±0.02, p < 0.001 respectively). A significant correlation was detected between the cTp-e time and the Tp-e/QT ratio and the PASI score in the group of psoriatic patients (r = 0.51, p < 0.001; r = 0.59, p < 0.001, respectively). Conclusions In our study, we detected a significant increase in the Tp-e interval and the Tp-e/QT ratio in patients with psoriasis vulgaris. The Tp-e interval and the Tp-e/QT ratio may be predictors for ventricular arrhythmias in patients with psoriasis vulgaris. PMID:27904512

Severity of Vision Loss Interacts With Word-Specific Features to Impact Out-Loud Reading in Glaucoma

PubMed Central

Mathews, Priya M.; Rubin, Gary S.; McCloskey, Michael; Salek, Sherveen; Ramulu, Pradeep Y.

2015-01-01

Purpose. To assess the impact of glaucoma-related vision loss on measures of out-loud reading, including time to say individual words, interval time between consecutive words, lexical errors, skipped words, and repetitions. Methods. Glaucoma subjects (n = 63) with bilateral visual field loss and glaucoma suspect controls (n = 57) were recorded while reading a standardized passage out loud. A masked evaluator determined the start and end of each recorded word and identified reading errors. Results. Glaucoma subjects demonstrated longer durations to recite individual words (265 vs. 243 ms, P < 0.001), longer intervals between words (154 vs. 124 ms, P < 0.001), and longer word/post-word interval complexes (the time spanned by the word and the interval following the word; 419 vs. 367 ms, P < 0.001) than controls. In multivariable analyses, each 0.1 decrement in log contrast sensitivity (logCS) was associated with a 15.0 ms longer word/post-interval complex (95% confidence interval [CI] = 9.6–20.4; P < 0.001). Contrast sensitivity was found to significantly interact with word length, word frequency, and word location at the end of a line with regards to word/post-word interval complex duration (P < 0.05 for all). Glaucoma severity was also associated with more lexical errors (Odds ratio = 1.20 for every 0.1 logCS decrement; 95% CI = 1.02–1.39, P < 0.05), but not with more skipped or repeated words. Conclusions. Glaucoma patients with greater vision loss make more lexical errors, are slower in reciting longer and less frequently used words, and more slowly transition to new lines of text. These problem areas may require special attention when designing methods to rehabilitate reading in patients with glaucoma. PMID:25737150

Oral Contraceptives Attenuate Cardiac Autonomic Responses to Musical Auditory Stimulation: Pilot Study.

PubMed

Milan, Réveni Carmem; Plassa, Bruna Oliveira; Guida, Heraldo Lorena; de Abreu, Luiz Carlos; Gomes, Rayana L; Garner, David M; Valenti, Vitor E

2015-01-01

The literature presents contradictory results regarding the effects of contraceptives on cardiac autonomic regulation. The research team aimed to evaluate the effects of musical auditory stimulation on cardiac autonomic regulation in women who use oral contraceptives. The research team designed a transversal observational pilot study. The setting was the Centro de Estudos do Sistema Nervoso Autônomo (CESNA) in the Departamento de Fonoaudiologia at the Universidade Estadual Paulista (UNESP) in Marília, SP, Brazil. Participants were 22 healthy nonathletic and nonsedentary females, all nonsmokers and aged between 18 and 27 y. Participants were divided into 2 groups: (1) 12 women who were not taking oral contraceptives, the control group; and (2) 10 women who were taking oral contraceptives, the oral contraceptive group. In the first stage, a rest control, the women sat with their earphones turned off for 20 min. After that period, the participants were exposed to 20 min of classical baroque music (ie, "Canon in D Major," Johann Pachelbel), at 63-84 dB. Measurements of the equivalent sound levels were conducted in a soundproof room, and the intervals between consecutive heartbeats (R-R intervals) were recorded, with a sampling rate of 1000 Hz. For calculation of the linear indices, the research team used software to perform an analysis of heart rate variability (HRV). Linear indices of HRV were analyzed in the time domain: (1) the standard deviation of normal-to-normal R-R intervals (SDNN), (2) the root-mean square of differences between adjacent normal R-R intervals in a time interval (RMSSD), and (3) the percentage of adjacent R-R intervals with a difference of duration greater than 50 ms (pNN50). The study also analyzed the frequency domain-low frequency (LF), high frequency (HF), and LF/HF ratio. For the control group, the musical auditory stimulation reduced (1) the SDNN from 52.2 ± 10 ms to 48.4 ± 16 ms (P = .0034); (2) the RMSSD from 45.8 ± 22 ms to 41.2 ± 19 ms (P = .0128); (3) the pNN50 from 25.5 ± 19 to 22.0 ± 18 (P = .0211); and (4) the LF (ms2) from 954.8 ± 457 ms2 to 686.2 ± 491 ms2 (P = .0024). In the oral contraceptive group, no significant changes occurred for the HRV indices during exposure to music. Musical auditory stimulation had a greater influence on cardiac autonomic regulation in women who did not use oral contraceptives.

Absorption spectrum of a two-level system subjected to a periodic pulse sequence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fotso, H. F.; Dobrovitski, V. V.

We investigate how the quantum control of a two-level system (TLS) coupled to photons can modify and tune the TLS’s photon absorption spectrum. Tuning and controlling the emission and the absorption is of much interest e.g. for the development of efficient interfaces between stationary and flying qubits in modern architectures for quantum computation and quantum communication. We consider the periodic pulse control, where the TLS is subjected to a periodic sequence of the near-resonant Rabi driving pulses, each pulse implementing a 180° rotation. For small inter-pulse delays, the absorption spectrum features a pronounced peak of stimulated emission at the pulsemore » frequency, as well as equidistant satellite peaks with smaller spectral weights. As long as the detuning between the carrier frequency of the driving and the TLS transition frequency remains moderate, this spectral shape shows little change. Therefore, the quantum control allows shifting the absorption peak to a desired position, and locks the absorption peak to the carrier frequency of the driving pulses. Detailed description of the spectrum, and its evolution as a function time, the inter-pulse spacing and the detuning, is presented.« less

Absorption spectrum of a two-level system subjected to a periodic pulse sequence

DOE PAGES

Fotso, H. F.; Dobrovitski, V. V.

2017-06-01

We investigate how the quantum control of a two-level system (TLS) coupled to photons can modify and tune the TLS’s photon absorption spectrum. Tuning and controlling the emission and the absorption is of much interest e.g. for the development of efficient interfaces between stationary and flying qubits in modern architectures for quantum computation and quantum communication. We consider the periodic pulse control, where the TLS is subjected to a periodic sequence of the near-resonant Rabi driving pulses, each pulse implementing a 180° rotation. For small inter-pulse delays, the absorption spectrum features a pronounced peak of stimulated emission at the pulsemore » frequency, as well as equidistant satellite peaks with smaller spectral weights. As long as the detuning between the carrier frequency of the driving and the TLS transition frequency remains moderate, this spectral shape shows little change. Therefore, the quantum control allows shifting the absorption peak to a desired position, and locks the absorption peak to the carrier frequency of the driving pulses. Detailed description of the spectrum, and its evolution as a function time, the inter-pulse spacing and the detuning, is presented.« less

Simultaneous manipulation and observation of multiple ro-vibrational eigenstates in solid para-hydrogen.

PubMed

Katsuki, Hiroyuki; Ohmori, Kenji

2016-09-28

We have experimentally performed the coherent control of delocalized ro-vibrational wave packets (RVWs) of solid para-hydrogen (p-H 2 ) by the wave packet interferometry (WPI) combined with coherent anti-Stokes Raman scattering (CARS). RVWs of solid p-H 2 are delocalized in the crystal, and the wave function with wave vector k ∼ 0 is selectively excited via the stimulated Raman process. We have excited the RVW twice by a pair of femtosecond laser pulses with delay controlled by a stabilized Michelson interferometer. Using a broad-band laser pulse, multiple ro-vibrational states can be excited simultaneously. We have observed the time-dependent Ramsey fringe spectra as a function of the inter-pulse delay by a spectrally resolved CARS technique using a narrow-band probe pulse, resolving the different intermediate states. Due to the different fringe oscillation periods among those intermediate states, we can manipulate their amplitude ratio by tuning the inter-pulse delay on the sub-femtosecond time scale. The state-selective manipulation and detection of the CARS signal combined with the WPI is a general and efficient protocol for the control of the interference of multiple quantum states in various quantum systems.

Effects of electrical stimulation of the hunger center in the lateral hypothalamus and food reinforcement on impulse activity of the mylohyoid muscle in rabbits under conditions of hunger and satiety.

PubMed

Ignatova, Ju P; Kromin, A A

2011-03-01

Effects of electrical stimulation of the hunger center in the lateral hypothalamus and food reinforcement on impulse activity of mylohyoid muscle were studied in chronic experiments under conditions of hunger and satiety. Threshold stimulation of the lateral hypothalamus in starving and satiated rabbits in the absence of food induced searching behavior associated with burst-like impulse activity with a bimodal distribution of interpulse intervals. Regular spike burst in the mylohyoid muscle during stimulation of the lateral hypothalamus in the absence of food serves as an example of the anticipatory type reaction. Increased food motivation during threshold stimulation of the lateral hypothalamus in starving and satiated rabbits with food offered led to successful food-procuring behavior, during which the frequency of spike bursts in the mylohyoid muscle became comparable with that under conditions of natural foraging behavior stimulated by the need in nutrients. Our results suggest that temporal structure of mylohyoid muscle impulse activity reflects convergent interactions of food-motivation excitation with reinforcement excitation on neurons of the masticatory and deglutitive centers.

Fin whale song variability in southern California and the Gulf of California.

PubMed

Širović, Ana; Oleson, Erin M; Buccowich, Jasmine; Rice, Ally; Bayless, Alexandra R

2017-08-31

Songs are distinct, patterned sounds produced by a variety of animals including baleen whales. Fin whale songs, which consist of short pulses repeated at regular interpulse intervals (IPIs), have been suggested as a tool to distinguish populations. Fin whale songs were analyzed from data collected from 2000-2012 in Southern California and from 2004-2010 in the Gulf of California using autonomous acoustic recorders. IPIs were measured for each identifiable song sequence during two random days of each month with recordings. Four distinct song types were identified: long doublet, short doublet, long triplet, and short triplet. Long and short doublets were the dominant songs in Southern California, while long and short triplets were dominant in the Gulf of California. An abrupt change in song type occurred in both areas during the monitoring period. We argue that each song type is unique to a population and these changes represent a shift in the primary population in the monitoring area. Occasional temporal and spatial song overlap indicated some exchange or visitation among populations. Fin whales appear to synchronize and gradually modify song rhythm over long time scales. A better understanding of the evolutionary and ecological importance of songs to fin whale populations is needed.

EVOLUTION OF DIVERGENT FEMALE MATING PREFERENCE IN RESPONSE TO EXPERIMENTAL SEXUAL SELECTION

PubMed Central

Debelle, Allan; Ritchie, Michael G; Snook, Rhonda R

2014-01-01

Sexual selection is predicted to drive the coevolution of mating signals and preferences (mating traits) within populations, and could play a role in speciation if sexual isolation arises due to mating trait divergence between populations. However, few studies have demonstrated that differences in mating traits between populations result from sexual selection alone. Experimental evolution is a promising approach to directly examine the action of sexual selection on mating trait divergence among populations. We manipulated the opportunity for sexual selection (low vs. high) in populations of Drosophila pseudoobscura. Previous studies on these experimental populations have shown that sexual selection manipulation resulted in the divergence between sexual selection treatments of several courtship song parameters, including interpulse interval (IPI) which markedly influences male mating success. Here, we measure female preference for IPI using a playback design to test for preference divergence between the sexual selection treatments after 130 generations of experimental sexual selection. The results suggest that female preference has coevolved with male signal, in opposite directions between the sexual selection treatments, providing direct evidence of the ability of sexual selection to drive the divergent coevolution of mating traits between populations. We discuss the implications in the context sexual selection and speciation. PMID:24931497

Substitution of (R,S)-methadone by (R)-methadone: Impact on QTc interval.

PubMed

Ansermot, Nicolas; Albayrak, Ozgür; Schläpfer, Jürg; Crettol, Séverine; Croquette-Krokar, Marina; Bourquin, Michel; Déglon, Jean-Jacques; Faouzi, Mohamed; Scherbaum, Norbert; Eap, Chin B

2010-03-22

Methadone is administered as a chiral mixture of (R,S)-methadone. The opioid effect is mainly mediated by (R)-methadone, whereas (S)-methadone blocks the human ether-à-go-go-related gene (hERG) voltage-gated potassium channel more potently, which can cause drug-induced long QT syndrome, leading to potentially lethal ventricular tachyarrhythmias. To investigate whether substitution of (R,S)-methadone by (R)-methadone could reduce the corrected QT (QTc) interval, (R,S)-methadone was replaced by (R)-methadone (half-dose) in 39 opioid-dependent patients receiving maintenance treatment for 14 days. (R)-methadone was then replaced by the initial dose of (R,S)-methadone for 14 days (n = 29). Trough (R)-methadone and (S)-methadone plasma levels and electrocardiogram measurements were taken. The Fridericia-corrected QT (QTcF) interval decreased when (R,S)-methadone was replaced by a half-dose of (R)-methadone; the median (interquartile range [IQR]) values were 423 (398-440) milliseconds (ms) and 412 (395-431) ms (P = .06) at days 0 and 14, respectively. Using a univariate mixed-effect linear model, the QTcF value decreased by a mean of -3.9 ms (95% confidence interval [CI], -7.7 to -0.2) per week (P = .04). The QTcF value increased when (R)-methadone was replaced by the initial dose of (R,S)-methadone for 14 days; median (IQR) values were 424 (398-436) ms and 424 (412-443) ms (P = .01) at days 14 and 28, respectively. The univariate model showed that the QTcF value increased by a mean of 4.7 ms (95% CI, 1.3-8.1) per week (P = .006). Substitution of (R,S)-methadone by (R)-methadone reduces the QTc interval value. A safer cardiac profile of (R)-methadone is in agreement with previous in vitro and pharmacogenetic studies. If the present results are confirmed by larger studies, (R)-methadone should be prescribed instead of (R,S)-methadone to reduce the risk of cardiac toxic effects and sudden death.

Comparison of automated measurements of electrocardiographic intervals and durations by computer-based algorithms of digital electrocardiographs.

PubMed

Kligfield, Paul; Badilini, Fabio; Rowlandson, Ian; Xue, Joel; Clark, Elaine; Devine, Brian; Macfarlane, Peter; de Bie, Johan; Mortara, David; Babaeizadeh, Saeed; Gregg, Richard; Helfenbein, Eric D; Green, Cynthia L

2014-02-01

Automated measurements of electrocardiographic (ECG) intervals are widely used by clinicians for individual patient diagnosis and by investigators in population studies. We examined whether clinically significant systematic differences exist in ECG intervals measured by current generation digital electrocardiographs from different manufacturers and whether differences, if present, are dependent on the degree of abnormality of the selected ECGs. Measurements of RR interval, PR interval, QRS duration, and QT interval were made blindly by 4 major manufacturers of digital electrocardiographs used in the United States from 600 XML files of ECG tracings stored in the US FDA ECG warehouse and released for the purpose of this study by the Cardiac Safety Research Consortium. Included were 3 groups based on expected QT interval and degree of repolarization abnormality, comprising 200 ECGs each from (1) placebo or baseline study period in normal subjects during thorough QT studies, (2) peak moxifloxacin effect in otherwise normal subjects during thorough QT studies, and (3) patients with genotyped variants of congenital long QT syndrome (LQTS). Differences of means between manufacturers were generally small in the normal and moxifloxacin subjects, but in the LQTS patients, differences of means ranged from 2.0 to 14.0 ms for QRS duration and from 0.8 to 18.1 ms for the QT interval. Mean absolute differences between algorithms were similar for QRS duration and QT intervals in the normal and in the moxifloxacin subjects (mean ≤6 ms) but were significantly larger in patients with LQTS. Small but statistically significant group differences in mean interval and duration measurements and means of individual absolute differences exist among automated algorithms of widely used, current generation digital electrocardiographs. Measurement differences, including QRS duration and the QT interval, are greatest for the most abnormal ECGs. © 2014.

L2-L1 Translation Priming Effects in a Lexical Decision Task: Evidence From Low Proficient Korean-English Bilinguals

PubMed Central

Lee, Yoonhyoung; Jang, Euna; Choi, Wonil

2018-01-01

One of the key issues in bilingual lexical representation is whether L1 processing is facilitated by L2 words. In this study, we conducted two experiments using the masked priming paradigm to examine how L2-L1 translation priming effects emerge when unbalanced, low proficiency, Korean-English bilinguals performed a lexical decision task. In Experiment 1, we used a 150 ms SOA (50 ms prime duration followed by a blank interval of 100 ms) and found a significant L2-L1 translation priming effect. In contrast, in Experiment 2, we used a 60 ms SOA (50 ms prime duration followed by a blank interval of 10 ms) and found a null effect of L2-L1 translation priming. This finding is the first demonstration of a significant L2-L1 translation priming effect with unbalanced Korean-English bilinguals. Implications of this work are discussed with regard to bilingual word recognition models. PMID:29599733

Effects of phenobarbital and levetiracetam on PR and QTc intervals in patients with post-stroke seizure.

PubMed

Siniscalchi, Antonio; Scaglione, Francesco; Sanzaro, Enzo; Iemolo, Francesco; Albertini, Giorgio; Quirino, Gianluca; Manes, Maria Teresa; Gratteri, Santo; Mercuri, Nicola Biagio; De Sarro, Giovambattista; Gallelli, Luca

2014-12-01

Sudden unexplained/unexpected death (SUDEP) is related to high mortality in patients with epilepsy. The prolongation of QT interval, involved in cardiac arrhythmia-related SUDEP, may be precipitated by antiepileptic drugs (AEDs). In this study, we evaluated the effects of phenobarbital and levetiracetam on PR-QTc intervals in patients with post-stroke seizures. We performed an open-label, parallel group, prospective, multicenter study between June 2009 and December 2013 in patients older than 18 years of age with a clinical diagnosis of post-stroke seizure and treated with phenobarbital or levetiracetam. In order to exclude a role of cerebral post-stroke injury on modulation of PR and QTc intervals, patients with cerebral post-stroke injury and without seizures were also enrolled as controls. Interictal electrocardiography analysis revealed no significant difference in PR interval between patients treated with an AED (n = 49) and control patients (n = 50) (181.25 ± 12.05 vs. 182.4 ± 10.3 ms; p > 0.05). In contrast, a significantly longer QTc interval was recorded in patients treated with an AED compared with control patients (441.2 ± 56.6 vs. 396.8 ± 49.3 ms; p < 0.01). Patients treated with phenobarbital showed a significantly longer QTc interval than patients treated with levetiracetam (460.0 ± 57.2 vs. 421.5 ± 50.1 ms; p < 0.05). The study reported that in patients with late post-stroke seizures, phenobarbital prolonged QTc interval more so than levetiracetam.

Prevalence and risk factors for prolonged QT interval and QT dispersion in patients with type 2 diabetes.

PubMed

Ninkovic, Vladan M; Ninkovic, Srdjan M; Miloradovic, Vanja; Stanojevic, Dejan; Babic, Marijana; Giga, Vojislav; Dobric, Milan; Trenell, Michael I; Lalic, Nebojsa; Seferovic, Petar M; Jakovljevic, Djordje G

2016-10-01

Prolonged QT interval is associated with cardiac arrhythmias and sudden death. The present study determined the prevalence of prolonged QT interval and QT dispersion and defined their clinical and metabolic predictors in patients with type 2 diabetes. Cross-sectional study included 501 patients with type 2 diabetes. A standard 12-lead electrocardiogram was recorded. QT corrected for heart rate (QTc) >440 ms and QT dispersion (QTd) >80 ms were considered abnormally prolonged. QTc ≥ 500 ms was considered a high-risk QTc prolongation. Demographic, clinical and laboratory data were collected. Independent risk factors for prolonged QTc and QTd were assessed using logistic regression analysis. Prevalence of QTc > 440 ms and QTd > 80 ms were 44.1 and 3.6 %, respectively. Prevalence of high-risk QTc (≥500 ms) was 2 % only. Independent risk factors for QTc prolongation >440 ms were mean blood glucose (β = 2.192, p < 0.001), treatment with sulphonylurea (β = 5.198, p = 0.027), female gender (β = 8.844, p < 0.001), and coronary heart disease (β = 8.636, p = 0.001). Independent risk factors for QTc ≥ 500 ms were coronary heart disease (β = 4.134, p < 0.001) and mean blood glucose level (β = 1.735, p < 0.001). The independent risk factor for prolonged QTd was only coronary heart disease (β = 5.354, p < 0.001). Although the prevalence of prolonged QTc > 440 ms is significant, the prevalence of high-risk QTc (≥500 ms) and QTd > 80 ms is very low in patients with type 2 diabetes. Hyperglycaemia and coronary heart disease are strong predictors of high-risk QTc.

Automated saliva processing for LC-MS/MS: Improving laboratory efficiency in cortisol and cortisone testing.

PubMed

Antonelli, Giorgia; Padoan, Andrea; Artusi, Carlo; Marinova, Mariela; Zaninotto, Martina; Plebani, Mario

2016-04-01

The aim of this study was to implement in our routine practice an automated saliva preparation protocol for quantification of cortisol (F) and cortisone (E) by LC-MS/MS using a liquid handling platform, maintaining the previously defined reference intervals with the manual preparation. Addition of internal standard solution to saliva samples and calibrators and SPE on μ-elution 96-well plate were performed by liquid handling platform. After extraction, the eluates were submitted to LC-MS/MS analysis. The manual steps within the entire process were to transfer saliva samples in suitable tubes, to put the cap mat and transfer of the collection plate to the LC auto sampler. Transference of the reference intervals from the manual to the automated procedure was established by Passing Bablok regression on 120 saliva samples analyzed simultaneously with the two procedures. Calibration curves were linear throughout the selected ranges. The imprecision ranged from 2 to 10%, with recoveries from 95 to 116%. Passing Bablok regression demonstrated no significant bias. The liquid handling platform translates the manual steps into automated operations allowing for saving hands-on time, while maintaining assay reproducibility and ensuring reliability of results, making it implementable in our routine with the previous established reference intervals. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Kinetic processes determining attainable pulse repetition rate in pulsed metal vapor lasers

NASA Astrophysics Data System (ADS)

Petrash, Gueorgii G.

1998-06-01

A review of the investigations of the main processes determining the attainable pulse repetition rate of elemental metal vapor pulsed gas discharge self-terminating lasers, such as copper vapor laser, gold vapor laser, lead vapor laser, is given. Kinetic processes during an excitation pulse and interpulse period are considered as well as experiments with lasers operating at high repetition rate.

Standardization of magnetocardiography in nonhuman primates

NASA Astrophysics Data System (ADS)

Seki, Yusuke; Muneyuki, Kenta; Kandori, Akihiko; Tsukada, Keiji; Terao, Keiji; Ageyama, Naohide

2008-03-01

To establish the electrophysiological mappings of nonhuman primates by using magnetocardiogram (MCG) data and obtain the normal values of MCG parameters, we used 64-channel superconducting quantum interference devices to measure 8 × 8 MCG data for 95 cynomolgus monkeys (Macaca fascicularis, 51 female and 44 male). The PQ interval, QRS duration, QT interval and QTc were respectively 79 ± 14 ms, 42 ± 7 ms, 222 ± 23 ms and 363 ± 25 (mean ± SD), and these parameters did not differ significantly between female and male monkeys. These results indicate the normal values of the MCG parameters of the cynomolgus monkey and should facilitate animal experiments in magnetocardiography.

Venetoclax does not prolong the QT interval in patients with hematological malignancies: an exposure-response analysis.

PubMed

Freise, Kevin J; Dunbar, Martin; Jones, Aksana K; Hoffman, David; Enschede, Sari L Heitner; Wong, Shekman; Salem, Ahmed Hamed

2016-10-01

Venetoclax (ABT-199/GDC-0199) is a selective first-in-class B cell lymphoma-2 inhibitor being developed for the treatment of hematological malignancies. The aim of this study was to determine the potential of venetoclax to prolong the corrected QT (QTc) interval and to evaluate the relationship between systemic venetoclax concentration and QTc interval. The study population included 176 male and female patients with relapsed or refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (n = 105) or non-Hodgkin's lymphoma (n = 71) enrolled in a phase 1 safety, pharmacokinetic, and efficacy study. Electrocardiograms were collected in triplicate at time-matched points (2, 4, 6, and 8 h) prior to the first venetoclax administration and after repeated venetoclax administration to achieve steady state conditions. Venetoclax doses ranged from 100 to 1200 mg daily. Plasma venetoclax samples were collected after steady state electrocardiogram measurements. The mean and upper bound of the 2-sided 90 % confidence interval (CI) QTc change from baseline were <5 and <10 ms, respectively, at all time points and doses (<400, 400, and >400 mg). Three subjects had single QTc values >500 ms and/or ΔQTc > 60 ms. The effect of venetoclax concentration on both ΔQTc and QTc was not statistically significant (P > 0.05). At the mean maximum concentrations achieved with therapeutic (400 mg) and supra-therapeutic (1200 mg) venetoclax doses, the estimated drug effects on QTc were 0.137 (90 % CI [-1.01 to 1.28]) and 0.263 (90 % CI [-1.92 to 2.45]) ms, respectively. Venetoclax does not prolong QTc interval even at supra-therapeutic doses, and there is no relationship between venetoclax concentrations and QTc interval.

Spike Timing Matters in Novel Neuronal Code Involved in Vibrotactile Frequency Perception.

PubMed

Birznieks, Ingvars; Vickery, Richard M

2017-05-22

Skin vibrations sensed by tactile receptors contribute significantly to the perception of object properties during tactile exploration [1-4] and to sensorimotor control during object manipulation [5]. Sustained low-frequency skin vibration (<60 Hz) evokes a distinct tactile sensation referred to as flutter whose frequency can be clearly perceived [6]. How afferent spiking activity translates into the perception of frequency is still unknown. Measures based on mean spike rates of neurons in the primary somatosensory cortex are sufficient to explain performance in some frequency discrimination tasks [7-11]; however, there is emerging evidence that stimuli can be distinguished based also on temporal features of neural activity [12, 13]. Our study's advance is to demonstrate that temporal features are fundamental for vibrotactile frequency perception. Pulsatile mechanical stimuli were used to elicit specified temporal spike train patterns in tactile afferents, and subsequently psychophysical methods were employed to characterize human frequency perception. Remarkably, the most salient temporal feature determining vibrotactile frequency was not the underlying periodicity but, rather, the duration of the silent gap between successive bursts of neural activity. This burst gap code for frequency represents a previously unknown form of neural coding in the tactile sensory system, which parallels auditory pitch perception mechanisms based on purely temporal information where longer inter-pulse intervals receive higher perceptual weights than short intervals [14]. Our study also demonstrates that human perception of stimuli can be determined exclusively by temporal features of spike trains independent of the mean spike rate and without contribution from population response factors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancing Heart-Beat-Based Security for mHealth Applications.

PubMed

Seepers, Robert M; Strydis, Christos; Sourdis, Ioannis; De Zeeuw, Chris I

2017-01-01

In heart-beat-based security, a security key is derived from the time difference between consecutive heart beats (the inter-pulse interval, IPI), which may, subsequently, be used to enable secure communication. While heart-beat-based security holds promise in mobile health (mHealth) applications, there currently exists no work that provides a detailed characterization of the delivered security in a real system. In this paper, we evaluate the strength of IPI-based security keys in the context of entity authentication. We investigate several aspects that should be considered in practice, including subjects with reduced heart-rate variability (HRV), different sensor-sampling frequencies, intersensor variability (i.e., how accurate each entity may measure heart beats) as well as average and worst-case-authentication time. Contrary to the current state of the art, our evaluation demonstrates that authentication using multiple, less-entropic keys may actually increase the key strength by reducing the effects of intersensor variability. Moreover, we find that the maximal key strength of a 60-bit key varies between 29.2 bits and only 5.7 bits, depending on the subject's HRV. To improve security, we introduce the inter-multi-pulse interval (ImPI), a novel method of extracting entropy from the heart by considering the time difference between nonconsecutive heart beats. Given the same authentication time, using the ImPI for key generation increases key strength by up to 3.4 × (+19.2 bits) for subjects with limited HRV, at the cost of an extended key-generation time of 4.8 × (+45 s).

A 2:1 AV rhythm: an adverse effect of a long AV delay during DDI pacing and its prevention by the ventricular intrinsic preference algorithm in DDD mode.

PubMed

Minamiguchi, Hitoshi; Oginosawa, Yasushi; Kohno, Ritsuko; Tamura, Masahito; Takeuchi, Masaaki; Otsuji, Yutaka; Abe, Haruhiko

2012-07-01

A 91-year-old woman received a dual-chamber pacemaker for sick sinus syndrome and intermittently abnormal atrioventricular (AV) conduction. The pacemaker was set in DDI mode with a 350-ms AV delay to preserve intrinsic ventricular activity. She complained of palpitation during AV sequential pacing. The electrocardiogram showed a 2:1 AV rhythm from 1:1 ventriculoatrial (VA) conduction during ventricular pacing in DDI mode with a long AV interval. After reprogramming of the pacemaker in DDD mode with a 250-ms AV interval and additional 100-ms prolongation of the AV interval by the ventricular intrinsic preference function, VA conduction disappeared and the patient's symptom were alleviated without increasing unnecessary right ventricular pacing. ©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.

Programming Cardiac Resynchronization Therapy for Electrical Synchrony: Reaching Beyond Left Bundle Branch Block and Left Ventricular Activation Delay.

PubMed

Varma, Niraj; O'Donnell, David; Bassiouny, Mohammed; Ritter, Philippe; Pappone, Carlo; Mangual, Jan; Cantillon, Daniel; Badie, Nima; Thibault, Bernard; Wisnoskey, Brian

2018-02-06

QRS narrowing following cardiac resynchronization therapy with biventricular (BiV) or left ventricular (LV) pacing is likely affected by patient-specific conduction characteristics (PR, qLV, LV-paced propagation interval), making a universal programming strategy likely ineffective. We tested these factors using a novel, device-based algorithm (SyncAV) that automatically adjusts paced atrioventricular delay (default or programmable offset) according to intrinsic atrioventricular conduction. Seventy-five patients undergoing cardiac resynchronization therapy (age 66±11 years; 65% male; 32% with ischemic cardiomyopathy; LV ejection fraction 28±8%; QRS duration 162±16 ms) with intact atrioventricular conduction (PR interval 194±34, range 128-300 ms), left bundle branch block, and optimized LV lead position were studied at implant. QRS duration (QRSd) reduction was compared for the following pacing configurations: nominal simultaneous BiV (Mode I: paced/sensed atrioventricular delay=140/110 ms), BiV+SyncAV with 50 ms offset (Mode II), BiV+SyncAV with offset that minimized QRSd (Mode III), or LV-only pacing+SyncAV with 50 ms offset (Mode IV). The intrinsic QRSd (162±16 ms) was reduced to 142±17 ms (-11.8%) by Mode I, 136±14 ms (-15.6%) by Mode IV, and 132±13 ms (-17.8%) by Mode II. Mode III yielded the shortest overall QRSd (123±12 ms, -23.9% [ P <0.001 versus all modes]) and was the only configuration without QRSd prolongation in any patient. QRS narrowing occurred regardless of QRSd, PR, or LV-paced intervals, or underlying ischemic disease. Post-implant electrical optimization in already well-selected patients with left bundle branch block and optimized LV lead position is facilitated by patient-tailored BiV pacing adjusted to intrinsic atrioventricular timing using an automatic device-based algorithm. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Factors associated with the development of atrial fibrillation in patients with rheumatic mitral stenosis.

PubMed

Ozaydin, Mehmet; Turker, Yasin; Varol, Ercan; Alaca, Sule; Erdogan, Dogan; Yilmaz, Nigar; Dogan, Abdullah

2010-06-01

The aim of this study was to evaluate the factors associated with the development of atrial fibrillation (AF) in patients with rheumatic mitral stenosis (MS). A total of 146 consecutive patients with rheumatic MS were screened. They were accepted to be in AF group and sinus rhythm group according to their rhythm in the baseline ECG. After screening, 38 patients were excluded due to hyperthyroidism (n = 13), chronic obstructive pulmonary disease (n = 22), malignancy (n = 2) and rheumatoid arthritis (n = 1). Therefore, remaining 108 patients, 74 of whom in sinus rhythm (MS-SR) and 34 of whom in AF (MS-AF) constituted study population. Fourty age- and gender-matched patients constituted control group. Factors associated with development of AF in multivariable analysis included High sensitivity C reactive protein (P = 0.005; odds ratio, 3.44; 95% confidence interval, 1.44-8.22), N-terminal of brain natriuretic peptide precursor (P < 0.0001; odds ratio, 1.03; 95% confidence interval, 1.02-1.06) and left atrial diameter (P < 0.0001; odds ratio, 1.68; 95% confidence interval, 1.32-2.14). Present study suggests that High sensitivity C reactive protein, N-terminal of brain natriuretic peptide precursor and left atrial diameter are associated with development AF in patients with MS.

Differentiating the origin of outflow tract ventricular arrhythmia using a simple, novel approach.

PubMed

Efimova, Elena; Dinov, Borislav; Acou, Willem-Jan; Schirripa, Valentina; Kornej, Jelena; Kosiuk, Jedrzej; Rolf, Sascha; Sommer, Philipp; Richter, Sergio; Bollmann, Andreas; Hindricks, Gerhard; Arya, Arash

2015-07-01

Numerous electrocardiographic (ECG) criteria have been proposed to identify localization of outflow tract ventricular arrhythmias (OT-VAs); however, in some cases, it is difficult to accurately localize the origin of OT-VA using the surface ECG. The purpose of this study was to assess a simple criterion for localization of OT-VAs during electrophysiology study. We measured the interval from the onset of the earliest QRS complex of premature ventricular contractions (PVCs) to the distal right ventricular apical signal (the QRS-RVA interval) in 66 patients (31 men aged 53.3 ± 14.0 years; right ventricular outflow tract [RVOT] origin in 37) referred for ablation of symptomatic outflow tract PVCs. We prospectively validated this criterion in 39 patients (22 men aged 52 ± 15 years; RVOT origin in 19). Compared with patients with RVOT PVCs, the QRS-RVA interval was significantly longer in patients with left ventricular outflow tract (LVOT) PVCs (70 ± 14 vs 33.4±10 ms, P < .001). Receiver operating characteristic analysis showed that a QRS-RVA interval ≥49 ms had sensitivity, specificity, and positive and negative predictive values of 100%, 94.6%, 93.5%, and 100%, respectively, for prediction of an LVOT origin. The same analysis in the validation cohort showed sensitivity, specificity, and positive and negative predictive values of 94.7%, 95%, 95%, and 94.7%, respectively. When these data were combined, a QRS-RVA interval ≥49 ms had sensitivity, specificity, and positive and negative predictive values of 98%, 94.6%, 94.1%, and 98.1%, respectively, for prediction of an LVOT origin. A QRS-RVA interval ≥49 ms suggests an LVOT origin. The QRS-RVA interval is a simple and accurate criterion for differentiating the origin of outflow tract arrhythmia during electrophysiology study; however, the accuracy of this criterion in identifying OT-VA from the right coronary cusp is limited. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Spatiotemporal brain dynamics of emotional face processing modulations induced by the serotonin 1A/2A receptor agonist psilocybin.

PubMed

Bernasconi, Fosco; Schmidt, André; Pokorny, Thomas; Kometer, Michael; Seifritz, Erich; Vollenweider, Franz X

2014-12-01

Emotional face processing is critically modulated by the serotonergic system. For instance, emotional face processing is impaired by acute psilocybin administration, a serotonin (5-HT) 1A and 2A receptor agonist. However, the spatiotemporal brain mechanisms underlying these modulations are poorly understood. Here, we investigated the spatiotemporal brain dynamics underlying psilocybin-induced modulations during emotional face processing. Electrical neuroimaging analyses were applied to visual evoked potentials in response to emotional faces, following psilocybin and placebo administration. Our results indicate a first time period of strength (i.e., Global Field Power) modulation over the 168-189 ms poststimulus interval, induced by psilocybin. A second time period of strength modulation was identified over the 211-242 ms poststimulus interval. Source estimations over these 2 time periods further revealed decreased activity in response to both neutral and fearful faces within limbic areas, including amygdala and parahippocampal gyrus, and the right temporal cortex over the 168-189 ms interval, and reduced activity in response to happy faces within limbic and right temporo-occipital brain areas over the 211-242 ms interval. Our results indicate a selective and temporally dissociable effect of psilocybin on the neuronal correlates of emotional face processing, consistent with a modulation of the top-down control. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Temporal structure in the light response of relay cells in the dorsal lateral geniculate nucleus of the cat.

PubMed Central

Funke, K; Wörgötter, F

1995-01-01

1. The spike interval pattern during the light responses of 155 on- and 81 off-centre cells of the dorsal lateral geniculate nucleus (LGN) was studied in anaesthetized and paralysed cats by the use of a novel analysis. Temporally localized interval distributions were computed from a 100 ms time window, which was shifted along the time axis in 10 ms steps, resulting in a 90% overlap between two adjacent windows. For each step the interval distribution was computed inside the time window with 1 ms resolution, and plotted as a greyscale-coded pixel line orthogonal to the time axis. For visual stimulation, light or dark spots of different size and contrast were presented with different background illumination levels. 2. Two characteristic interval patterns were observed during the sustained response component of the cells. Mainly on-cells (77%) responded with multimodal interval distributions, resulting in elongated 'bands' in the 2-dimensional time window plots. In similar situations, the interval distributions for most (71%) off-cells were rather wide and featureless. In those cases where interval bands (i.e. multimodal interval distributions) were observed for off-cells (14%), they were always much wider than for the on-cells. This difference between the on- and off-cell population was independent of the background illumination and the contrast of the stimulus. Y on-cells also tended to produce wider interval bands than X on-cells. 3. For most stimulation situations the first interval band was centred around 6-9 ms, which has been called the fundamental interval; higher order bands are multiples thereof. The fundamental interval shifted towards larger sizes with decreasing stimulus contrast. Increasing stimulus size, on the other hand, resulted in a redistribution of the intervals into higher order bands, while at the same time the location of the fundamental interval remained largely unaffected. This was interpreted as an effect of the increasing surround inhibition at the geniculate level, by which individual retinal EPSPs were cancelled. A changing level of adaptation can result in a mixed shift/redistribution effect because of the changing stimulus contrast and changing level of tonic inhibition. 4. The occurrence of interval bands is not directly related to the shape of the autocorrelation function, which can be flat, weakly oscillatory or strongly oscillatory, regardless of the interval band pattern. 5. A simple computer model was devised to account for the observed cell behaviour. The model is highly robust against parameter variations.(ABSTRACT TRUNCATED AT 400 WORDS) Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 15 PMID:7562612

Temporal prediction modulates the evaluative processing of "good" action feedback: An electrophysiological study.

PubMed

Kimura, Kenta; Kimura, Motohiro; Iwaki, Sunao

2016-10-01

The present study aimed to investigate whether or not the evaluative processing of action feedback can be modulated by temporal prediction. For this purpose, we examined the effects of the predictability of the timing of action feedback on an ERP effect that indexed the evaluative processing of action feedback, that is, an ERP effect that has been interpreted as a feedback-related negativity (FRN) elicited by "bad" action feedback or a reward positivity (RewP) elicited by "good" action feedback. In two types of experimental blocks, the participants performed a gambling task in which they chose one of two cards and received an action feedback that indicated monetary gain or loss. In fixed blocks, the time interval between the participant's choice and the onset of the action feedback was fixed at 0, 500, or 1,000 ms in separate blocks; thus, the timing of action feedback was predictable. In mixed blocks, the time interval was randomly chosen from the same three intervals with equal probability; thus, the timing was less predictable. The results showed that the FRN/RewP was smaller in mixed than fixed blocks for the 0-ms interval trial, whereas there was no difference between the two block types for the 500-ms and 1,000-ms interval trials. Interestingly, the smaller FRN/RewP was due to the modulation of gain ERPs rather than loss ERPs. These results suggest that temporal prediction can modulate the evaluative processing of action feedback, and particularly good feedback, such as that which indicates monetary gain. © 2016 Society for Psychophysiological Research.

Effects of auditory stimulation with music of different intensities on heart period

PubMed Central

do Amaral, Joice A.T.; Guida, Heraldo L.; de Abreu, Luiz Carlos; Barnabé, Viviani; Vanderlei, Franciele M.; Valenti, Vitor E.

2015-01-01

Various studies have indicated that music therapy with relaxant music improves cardiac function of patients treated with cardiotoxic medication and heavy-metal music acutely reduces heart rate variability (HRV). There is also evidence that white noise auditory stimulation above 50 dB causes cardiac autonomic responses. In this study, we aimed to evaluate the acute effects of musical auditory stimulation with different intensities on cardiac autonomic regulation. This study was performed on 24 healthy women between 18 and 25 years of age. We analyzed HRV in the time [standard deviation of normal-to-normal RR intervals (SDNN), percentage of adjacent RR intervals with a difference of duration >50 ms (pNN50), and root-mean square of differences between adjacent normal RR intervals in a time interval (RMSSD)] and frequency [low frequency (LF), high frequency (HF), and LF/HF ratio] domains. HRV was recorded at rest for 10 minutes. Subsequently, the volunteers were exposed to baroque or heavy-metal music for 5 minutes through an earphone. The volunteers were exposed to three equivalent sound levels (60–70, 70–80, and 80–90 dB). After the first baroque or heavy-metal music, they remained at rest for 5 minutes and then they were exposed to the other music. The sequence of songs was randomized for each individual. Heavy-metal musical auditory stimulation at 80–90 dB reduced the SDNN index compared with control (44.39 ± 14.40 ms vs. 34.88 ± 8.69 ms), and stimulation at 60–70 dB decreased the LF (ms2) index compared with control (668.83 ± 648.74 ms2 vs. 392.5 ± 179.94 ms2). Baroque music at 60–70 dB reduced the LF (ms2) index (587.75 ± 318.44 ms2 vs. 376.21 ± 178.85 ms2). In conclusion, heavy-metal and baroque musical auditory stimulation at lower intensities acutely reduced global modulation of the heart and only heavy-metal music reduced HRV at higher intensities. PMID:26870675

Cortical Plasticity Induction by Pairing Subthalamic Nucleus Deep-Brain Stimulation and Primary Motor Cortical Transcranial Magnetic Stimulation in Parkinson's Disease.

PubMed

Udupa, Kaviraja; Bahl, Nina; Ni, Zhen; Gunraj, Carolyn; Mazzella, Filomena; Moro, Elena; Hodaie, Mojgan; Lozano, Andres M; Lang, Anthony E; Chen, Robert

2016-01-13

Noninvasive brain stimulation studies have shown abnormal motor cortical plasticity in Parkinson's disease (PD). These studies used peripheral nerve stimulation paired with transcranial magnetic stimulation (TMS) to primary motor cortex (M1) at specific intervals to induce plasticity. Induction of cortical plasticity through stimulation of the basal ganglia (BG)-M1 connections has not been studied. In the present study, we used a novel technique of plasticity induction by repeated pairing of deep-brain stimulation (DBS) of the BG with M1 stimulation using TMS. We hypothesize that repeated pairing of subthalamic nucleus (STN)-DBS and M1-TMS at specific time intervals will lead to plasticity in the M1. Ten PD human patients with STN-DBS were studied in the on-medication state with DBS set to 3 Hz. The interstimulus intervals (ISIs) between STN-DBS and TMS that produced cortical facilitation were determined individually for each patient. Three plasticity induction conditions with repeated pairings (180 times) at specific ISIs (∼ 3 and ∼ 23 ms) that produced cortical facilitation and a control ISI of 167 ms were tested in random order. Repeated pairing of STN-DBS and M1-TMS at short (∼ 3 ms) and medium (∼ 23 ms) latencies increased M1 excitability that lasted for at least 45 min, whereas the control condition (fixed ISI of 167 ms) had no effect. There were no specific changes in motor thresholds, intracortical circuits, or recruitment curves. Our results indicate that paired-associative cortical plasticity can be induced by repeated STN and M1 stimulation at specific intervals. These results show that STN-DBS can modulate cortical plasticity. We introduced a new experimental paradigm to test the hypothesis that pairing subthalamic nucleus deep-brain stimulation (STN-DBS) with motor cortical transcranial magnetic stimulation (M1-TMS) at specific times can induce cortical plasticity in patients with Parkinson's disease (PD). We found that repeated pairing of STN-DBS with TMS at short (∼ 3 ms) and medium (∼ 23 ms) intervals increased cortical excitability that lasted for up to 45 min, whereas the control condition (fixed latency of 167 ms) had no effects on cortical excitability. This is the first demonstration of associative plasticity in the STN-M1 circuits in PD patients using this novel technique. The potential therapeutic effects of combining DBS and noninvasive cortical stimulation should be investigated further. Copyright © 2016 the authors 0270-6474/16/360397-09$15.00/0.

Superconducting Cavity Development for Free Electron Lasers.

DTIC Science & Technology

1986-06-30

effects have been modeled extensively using the code PARMELA, including finite space charge . The conflict is resolved through the use of harmonically...depends on the specifics of how the whole accelerator is run, i.e., bunch length, interpulse spacing , macrobunch length, charge per bunch, external...this indicates that the bunch length should be as long as possible. 2.4 OPTIMUM BUNCH LENGTH 20 Although wakefield, HOM excitation and space charge

Laser-induced fluorescence detection of lead atoms in a laser-induced plasma: An experimental analytical optimization study

NASA Astrophysics Data System (ADS)

Laville, Stéphane; Goueguel, Christian; Loudyi, Hakim; Vidal, François; Chaker, Mohamed; Sabsabi, Mohamad

2009-04-01

The combination of the laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) techniques was investigated to improve the limit of detection (LoD) of trace elements in solid matrices. The influence of the main experimental parameters on the LIF signal, namely the ablation fluence, the excitation energy, and the inter-pulse delay, was studied experimentally and a discussion of the results was presented. For illustrative purpose we considered detection of lead in brass samples. The plasma was produced by a Q-switched Nd:YAG laser and then re-excited by a nanosecond Optical Parametric Oscillator (OPO) laser. The experiments were performed in air at atmospheric pressure. We found out that the optimal conditions were obtained for our experimental set-up using relatively weak ablation fluence of 2-3 J/cm 2 and an inter-pulse delay of about 5-10 μs. Also, a few tens of microjoules was typically required to maximize the LIF signal. Using the LIBS-LIFS technique, a single-shot LoD for lead of about 1.5 part per million (ppm) was obtained while a value of 0.2 ppm was obtained after accumulating over 100 shots. These values represent an improvement of about two orders of magnitude with respect to LIBS.

Impairment of willed actions and use of advance information for movement preparation in schizophrenia

PubMed Central

Fuller, R.; Jahanshahi, M.

1999-01-01

OBJECTIVES—To assess willed actions in patients with schizophrenia using reaction time (RT) tasks that differ in the degree to which they involve volitionally controlled versus stimulus driven responses.
METHODS—Ten patients diagnosed with schizophrenia and 13 normal controls of comparable age were tested. Subjects performed a visual simple RT (SRT), an uncued four choice reaction time (CRT), and a fully cued four choice RT task. A stimulus 1(S1)−stimulus 2(S2) paradigm was used. The warning signal/precue (S1) preceded the imperative stimulus (S2) by either 0 (no warning signal or precue) 200, 800, 1600, or 3200ms.
RESULTS—The patients with schizophrenia had significantly slower RTs and movement times than normal subjects across all RT tasks. The unwarned SRT trials were significantly faster than the uncued CRT trials for both groups. For both groups, fully cued CRTs were significantly faster than the uncued CRTs. However, the S1−S2 interval had a differential effect on CRTs in the two groups. For the normal subjects fully cued CRTs and SRTs were equivalent when S1-S2 intervals were 800 ms or longer. A similar pattern of effects was not seen in the patients with schizophrenia, for whom the fully cued CRT were unexpectedly equivalent to SRT for the 200 ms interval and expectedly for the 1600 ms S1-S2 interval, but not the 3200 or 800 ms intervals.
CONCLUSIONS—Patients with schizophrenia were able to use advance information inherent in SRT or provided by the precue in fully cued CRT to speed up RT relative to uncued CRT. However, in the latter task, in which the volitional demands of preprogramming are higher since a different response has to be prepared on each trial, patients showed some unusual and inconsistent interval effects suggesting instability of attentional set. It is possible that future studies using RT tasks with higher volitional demands in patients with predominance of negative signs may disclose greater deficits in willed action in schizophrenia.

 PMID:10201424

Patients with left bundle branch block and left axis deviation show a specific left ventricular asynchrony pattern: Implications for left ventricular lead placement during CRT implantation.

PubMed

Sciarra, Luigi; Golia, Paolo; Palamà, Zefferino; Scarà, Antonio; De Ruvo, Ermenegildo; Borrelli, Alessio; Martino, Anna Maria; Minati, Monia; Fagagnini, Alessandro; Tota, Claudia; De Luca, Lucia; Grieco, Domenico; Delise, Pietro; Calò, Leonardo

Left bundle branch block (LBBB) and left axis deviation (LAD) patients may have poor response to resynchronization therapy (CRT). We sought to assess if LBBB and LAD patients show a specific pattern of mechanical asynchrony. CRT candidates with non-ischemic cardiomyopathy and LBBB were categorized as having normal QRS axis (within -30° and +90°) or LAD (within -30° and -90°). Patients underwent tissue Doppler imaging (TDI) to measure time interval between onset of QRS complex and peak systolic velocity in ejection period (Q-peak) at basal segments of septal, inferior, lateral and anterior walls, as expression of local timing of mechanical activation. Thirty patients (mean age 70.6years; 19 males) were included. Mean left ventricular ejection fraction was 0.28±0.06. Mean QRS duration was 172.5±13.9ms. Fifteen patients showed LBBB with LAD (QRS duration 173±14; EF 0.27±0.06). The other 15 patients had LBBB with a normal QRS axis (QRS duration 172±14; EF 0.29±0.05). Among patients with LAD, Q-peak interval was significantly longer at the anterior wall in comparison to each other walls (septal 201±46ms, inferior 242±58ms, lateral 267±45ms, anterior 302±50ms; p<0.0001). Conversely, in patients without LAD Q-peak interval was longer at lateral wall, when compared to each other (septal 228±65ms, inferior 250±64ms, lateral 328±98ms, anterior 291±86ms; p<0.0001). Patients with heart failure, presenting LBBB and LAD, show a specific pattern of ventricular asynchrony, with latest activation at anterior wall. This finding could affect target vessel selection during CRT procedures in these patients. Copyright © 2017 Elsevier Inc. All rights reserved.

Right Ventricular Pacing for Assessment of Cavo-Tricuspid Isthmus Block.

PubMed

Venkataraman, Ganesh; Wish, Marc; Friehling, Ted; Strickberger, S Adam

2016-01-01

Background: Cavo-tricuspid isthmus (CTI) dependent atrial flutter is typically treated with cardiac ablation. Standard techniques to assess CTI block after ablation can be technically challenging. Right ventricular (RV) pacing may allow for another technique to assess CTI block after ablation. Objective: The purpose of this study was to evaluate RV pacing as a method to assess CTI block after ablation of CTI dependent atrial flutter, and define endpoints of ablation using this technique. Methods: 28 patients undergoing ablation of CTI dependent atrial flutter with intact ventriculoatrial (VA) conduction were prospectively enrolled in this study and underwent the RV pacing protocol, as well as standard coronary sinus (CS) pacing techniques to assess CTI block. Results: The mean trans-isthmus conduction interval during CS pacing (TICI CS ) at 600 and 400ms after CTI ablation was 168 +/- 9ms and 175 +/- 18ms, respectively. The mean trans-isthmus conduction interval during RV pacing (TICI RV ) at 600ms and 400ms after CTI ablation was 109 +/- 5ms and 111 +/- 5ms, respectively. A TICI RV >100ms was associated with a successful outcome after CTI ablation. Conclusions: RV pacing may add incremental value in the assessment of CTI block in patients undergoing ablation of CTI dependent atrial flutter.

A modeling and simulation approach to characterize methadone QT prolongation using pooled data from five clinical trials in MMT patients.

PubMed

Florian, J; Garnett, C E; Nallani, S C; Rappaport, B A; Throckmorton, D C

2012-04-01

Pharmacokinetic (PK)-pharmacodynamic modeling and simulation were used to establish a link between methadone dose, concentrations, and Fridericia rate-corrected QT (QTcF) interval prolongation, and to identify a dose that was associated with increased risk of developing torsade de pointes. A linear relationship between concentration and QTcF described the data from five clinical trials in patients on methadone maintenance treatment (MMT). A previously published population PK model adequately described the concentration-time data, and this model was used for simulation. QTcF was increased by a mean (90% confidence interval (CI)) of 17 (12, 22) ms per 1,000 ng/ml of methadone. Based on this model, doses >120 mg/day would increase the QTcF interval by >20 ms. The model predicts that 1-3% of patients would have ΔQTcF >60 ms, and 0.3-2.0% of patients would have QTcF >500 ms at doses of 160-200 mg/day. Our predictions are consistent with available observational data and support the need for electrocardiogram (ECG) monitoring and arrhythmia risk factor assessment in patients receiving methadone doses >120 mg/day.

Reassessment of the Access Testosterone chemiluminescence assay and comparison with LC-MS method.

PubMed

Dittadi, Ruggero; Matteucci, Mara; Meneghetti, Elisa; Ndreu, Rudina

2018-03-01

To reassess the imprecision and Limit of Quantitation, to evaluate the cross-reaction with dehydroepiandrosterone-sulfate (DHEAS), the accuracy toward liquid chromatography-mass spectrometry (LC-MS) and the reference interval of the Access Testosterone method, performed by DxI immunoassay platform (Beckman Coulter). Imprecision was evaluated testing six pool samples assayed in 20 different run using two reagents lots. The cross-reaction with DHEAS was studied both by a displacement curve and by spiking DHEAS standard in two serum samples with known amount of testosterone. The comparison with LC-MS was evaluated by Passing-Bablock analysis in 21 routine serum samples and 19 control samples from an External Quality Assurance (EQA) scheme. The reference interval was verified by an indirect estimation on 2445 male and 2838 female outpatients. The imprecision study showed a coefficient of variation (CV) between 2.7% and 34.7% for serum pools from 16.3 and 0.27 nmol/L. The value of Limit of Quantitation at 20% CV was 0.53 nmol/L. The DHEAS showed a cross-reaction of 0.0074%. A comparison with LC-MS showed a trend toward a slight underestimation of immunoassay vs LC-MS (Passing-Bablock equations: DxI=-0.24+0.906 LCMS in serum samples and DxI=-0.299+0.981 LCMS in EQA samples). The verification of reference interval showed a 2.5th-97.5th percentile distribution of 6.6-24.3 nmol/L for male over 14 years and <0.5-2.78 nmol/L for female subjects, in accord with the reference intervals reported by the manufacturer. The Access Testosterone method could be considered an adequately reliable tool for the testosterone measurement. © 2017 Wiley Periodicals, Inc.

Electrocardiographic and blood pressure effects of energy drinks and Panax ginseng in healthy volunteers: A randomized clinical trial.

PubMed

Shah, Sachin A; Occiano, Andrew; Nguyen, Tinh An; Chan, Amanda; Sky, Joseph C; Bhattacharyya, Mouchumi; O'Dell, Kate M; Shek, Allen; Nguyen, Nancy N

2016-09-01

Energy drink usage has been linked to emergency room visits and deaths. The objective of the study is to assess the electrocardiographic and blood pressure effects of energy drinks, Panax ginseng and placebo in healthy individuals. This was a randomized, double blinded, placebo controlled, crossover study. Young healthy volunteers with no comorbid conditions consumed 32oz of an energy drink, control drink with 800mg of Panax ginseng or matching placebo-control drink over 45min. Primary endpoints were QTc interval and systolic blood pressure. Secondary endpoints included QT interval, PR interval, QRS duration, heart rate, and diastolic blood pressure. All endpoints were assessed at baseline, 1, 2, 3.5, and 5.5h. A significant increase in QTc interval 2h post energy drink consumption was evident when compared to placebo (3.37±10.7ms and -3.19±11.8ms respectively; p=0.030). Similarly, systolic blood pressure 2h post energy drink consumption increased when compared to placebo (2.00±6.37mmHg and -2.67±5.83mmHg respectively; p=0.014). The PR interval significantly reduced over a 2h period post energy drink use in a clinically non-meaningful manner. Heart rate at 2h was not significantly higher in the energy drink group when compared to others. The QT interval, QRS interval and diastolic blood pressure were not impacted at any time point. Certain energy drinks consumed at a high volume significantly increase the QTc interval and systolic blood pressure by over 6ms and 4mmHg respectively. Panax ginseng does not have a significant impact on ECG or blood pressure parameters. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Delta of the local ventriculo-atrial intervals at the septal location to differentiate tachycardia using septal accessory pathways from atypical atrioventricular nodal re-entry.

PubMed

Calvo, David; Pérez, Diego; Rubín, José; García, Daniel; Ávila, Pablo; Javier García-Fernández, F; Pachón, Marta; Bravo, Loreto; Hernández, Jesús; Miracle, Ángel L; Valverde, Irene; Gozalez-Vasserot, Mar; Árias, Miguel Ángel; Jimenez-Candíl, Javier; Morís, César

2018-01-02

Tachycardia mediated by septal accessory pathways (AP) and atypical atrioventricular nodal re-entry (AVNRT) require careful electrophysiologic evaluation for differential diagnosis. We aim to describe the differential behaviour of local ventriculo-atrial (VA) intervals which predicts the tachycardia mechanism. The local VA intervals at the para-Hisian septum were measured under three different situations: (i) tachycardia; (ii) sustained entrainment from the right ventricular apex (RVA); and (iii) continuous pacing from the RVA during sinus rhythm. Differences were computed as follows: Δ-VAentr = VA during entrainment - VA during tachycardia; and Δ-VApac = VA while pacing during sinus rhythm - VA during tachycardia. In contrast to AVNRT, we hypothesized that an invariable retrograde conduction through the septal AP will keep the result of the subtractions close to 0 ms in cases of ortodromic atrioventricular re-entrant tachycardia (AVRT). We analysed 55 atypical AVNRT (45% posterior type) and 82 AVRT (10 anteroseptal, 18 para-Hisian, 12 mid-septal, and 42 posteroseptal). Δ-VAentr was longer for AVNRT (98.5 ± 40.3 ms) compared with septal AP (-5.7 ± 19.3 ms; P < 0.001). A value of 50 ms showed 98.7% sensitivity and 92% specificity (AUC 0.99; 95% CI 0.98-1). According to physiological criteria, a negative Δ-VAentr remains unobserved in the case of AVNRT (positive predictive value 100% for septal AP). Δ-VApac was also longer for AVNRT (66.5 ± 14.6 ms) compared with septal AP (-9.7 ± 3.3 ms; P < 0.001). A value of 50 ms showed 100% sensitivity and 74% specificity (AUC 0.86; 95% CI 0.76-0.93). Delta of the local VA intervals enables distinction between atypical AVNRT and AVRT mediated by septal AP. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.

Emotion processing in the visual brain: a MEG analysis.

PubMed

Peyk, Peter; Schupp, Harald T; Elbert, Thomas; Junghöfer, Markus

2008-06-01

Recent functional magnetic resonance imaging (fMRI) and event-related brain potential (ERP) studies provide empirical support for the notion that emotional cues guide selective attention. Extending this line of research, whole head magneto-encephalogram (MEG) was measured while participants viewed in separate experimental blocks a continuous stream of either pleasant and neutral or unpleasant and neutral pictures, presented for 330 ms each. Event-related magnetic fields (ERF) were analyzed after intersubject sensor coregistration, complemented by minimum norm estimates (MNE) to explore neural generator sources. Both streams of analysis converge by demonstrating the selective emotion processing in an early (120-170 ms) and a late time interval (220-310 ms). ERF analysis revealed that the polarity of the emotion difference fields was reversed across early and late intervals suggesting distinct patterns of activation in the visual processing stream. Source analysis revealed the amplified processing of emotional pictures in visual processing areas with more pronounced occipito-parieto-temporal activation in the early time interval, and a stronger engagement of more anterior, temporal, regions in the later interval. Confirming previous ERP studies showing facilitated emotion processing, the present data suggest that MEG provides a complementary look at the spread of activation in the visual processing stream.

Effect of Moderate Versus High-Intensity Interval Exercise Training on Heart Rate Variability Parameters in Inactive Latin-American Adults: A Randomised Clinical Trial.

PubMed

Ramírez-Vélez, Robinson; Tordecilla-Sanders, Alejandra; Téllez-T, Luis Andrés; Camelo-Prieto, Diana; Hernández-Quiñonez, Paula Andrea; Correa-Bautista, Jorge Enrique; Garcia-Hermoso, Antonio; Ramírez-Campillo, Rodrigo; Izquierdo, Mikel

2017-02-01

We investigated the effect of moderate versus high-intensity interval exercise training on the HRV indices in physically inactive adults. Twenty inactive adults were randomly allocated to receive either moderate intensity training (MCT group) or high-intensity interval training (HIT group). The MCT group performed aerobic training at an intensity of 55-75%, which consisted of walking on a treadmill at 60-80% of the maximum heart rate (HRmax) until the expenditure of 300 kcal. The HIT group ran on a treadmill for 4 minutes at 85-95% peak HRmax and had a recovery of 4 minutes at 65% peak HRmax until the expenditure of 300 kcal. Supine resting HRV indices (time domain: SDNN, standard deviation of normal-to-normal intervals; rMSSD, Root mean square successive difference of RR intervals and frequency domain: HFLn, high-frequency spectral power; LF, low-frequency spectral power and HF/LF ratio) were measured at baseline and 12 weeks thereafter. The SDNN changes were 3.4 (8.9) ms in the MCT group and 29.1 (7.6) ms in the HIT group (difference between groups 32.6 [95% CI, 24.9 to 40.4 (P = 0.01)]. The LF/HFLn ratio change 0.19 (0.03) ms in the MCT group and 0.13 (0.01) ms in the HIT group (P between groups = 0.016). No significant group differences were observed for the rMSSD, HF and LF parameters. In inactive adults, this study showed that a 12-week HIT training program could increase short-term HRV, mostly in vagally mediated indices such as SDNN and HF/LFLn ratio power.

Characterization of Myocardial Repolarization Reserve in Adolescent Females With Anorexia Nervosa.

PubMed

Padfield, Gareth J; Escudero, Carolina A; DeSouza, Astrid M; Steinberg, Christian; Gibbs, Karen; Puyat, Joseph H; Lam, Pei Yoong; Sanatani, Shubhayan; Sherwin, Elizabeth; Potts, James E; Sandor, George; Krahn, Andrew D

2016-02-09

Patients with anorexia nervosa exhibit abnormal myocardial repolarization and are susceptible to sudden cardiac death. Exercise testing is useful in unmasking QT prolongation in disorders associated with abnormal repolarization. We characterized QT adaptation during exercise in anorexia. Sixty-one adolescent female patients with anorexia nervosa and 45 age- and sex-matched healthy volunteers performed symptom-limited cycle ergometry during 12-lead ECG monitoring. Changes in the QT interval during exercise were measured, and QT/RR-interval slopes were determined by using mixed-effects regression modeling. Patients had significantly lower body mass index than controls; however, resting heart rates and QT/QTc intervals were similar at baseline. Patients had shorter exercise times (13.7±4.5 versus 20.6±4.5 minutes; P<0.001) and lower peak heart rates (159±20 versus 184±9 beats/min; P<0.001). The mean QTc intervals were longer at peak exercise in patients (442±29 versus 422±19 ms; P<0.001). During submaximal exertion at comparable heart rates (114±6 versus 115±11 beats/min; P=0.54), the QTc interval had prolonged significantly more in patients than controls (37±28 versus 24±25 ms; P<0.016). The RR/QT slope, best described by a curvilinear relationship, was more gradual in patients than in controls (13.4; 95% confidence interval, 12.8-13.9 versus 15.8; 95% confidence interval, 15.3-16.4 ms QT change per 10% change in RR interval; P<0.001) and steepest in patients within the highest body mass index tertile versus the lowest (13.9; 95% confidence interval, 12.9-14.9 versus 12.3; 95% confidence interval, 11.3-13.3; P=0.026). Despite the absence of manifest QT prolongation, adolescent anorexic females have impaired repolarization reserve in comparison with healthy controls. Further study may identify impaired QT dynamics as a risk factor for arrhythmias in anorexia nervosa. © 2016 American Heart Association, Inc.

Fin whale tracks recorded by a seismic network on the Juan de Fuca Ridge, Northeast Pacific Ocean.

PubMed

Soule, Dax C; Wilcock, William S D

2013-03-01

Fin whale calls recorded from 2003 to 2004 by a seafloor seismic network on the Endeavour segment of the Juan de Fuca Ridge were analyzed to determine tracks and calling patterns. Over 150 tracks were obtained with a total duration of ~800 h and swimming speeds from 1 to 12 km/h. The dominant inter-pulse interval (IPI) is 24 s and the IPI patterns define 4 categories: a 25 s single IPI and 24/30 s dual IPI produced by single calling whales, a 24/13 s dual IPI interpreted as two calling whales, and an irregular IPI interpreted as groups of calling whales. There are also tracks in which the IPI switches between categories. Call rates vary seasonally with all the tracks between August and April. From August to October tracks are dominated by the irregular IPI and are predominantly headed to the northwest, suggesting that a portion of the fin whale population does not migrate south in the fall. The other IPI categories occur primarily from November to March. These tracks have slower swimming speeds, tend to meander, and are predominantly to the south. The distribution of fin whales around the network is non-random with more calls near the network and to the east and north.

Optimal size of stochastic Hodgkin-Huxley neuronal systems for maximal energy efficiency in coding pulse signals

NASA Astrophysics Data System (ADS)

Yu, Lianchun; Liu, Liwei

2014-03-01

The generation and conduction of action potentials (APs) represents a fundamental means of communication in the nervous system and is a metabolically expensive process. In this paper, we investigate the energy efficiency of neural systems in transferring pulse signals with APs. By analytically solving a bistable neuron model that mimics the AP generation with a particle crossing the barrier of a double well, we find the optimal number of ion channels that maximizes the energy efficiency of a neuron. We also investigate the energy efficiency of a neuron population in which the input pulse signals are represented with synchronized spikes and read out with a downstream coincidence detector neuron. We find an optimal number of neurons in neuron population, as well as the number of ion channels in each neuron that maximizes the energy efficiency. The energy efficiency also depends on the characters of the input signals, e.g., the pulse strength and the interpulse intervals. These results are confirmed by computer simulation of the stochastic Hodgkin-Huxley model with a detailed description of the ion channel random gating. We argue that the tradeoff between signal transmission reliability and energy cost may influence the size of the neural systems when energy use is constrained.

[Effect of electrostimulation "hunger center" of lateral hypothalamus on the impulse activity of masticatory muscles in unfed and fed rabbits in the absence and the presence of food].

PubMed

Ignatova, Iu P; Kromin, A A

2011-01-01

In chronic experiences on rabbits the influence of electrostimulation of "the hunger centres" of the lateral hypothalamus (LH) on impulse activity of chewing muscles of rabbits under the conditions of hunger and satiation was studied. It is established, threshold irritation of the LH of hungry and preliminary fed animals in the absence of food caused the occurrence of incessant search behavior which was followed by the regular generation of bursts of AP by masseter and mylohyoideus muscles with bimodal distributions of interpulse intervals. Such reaction of chewing muscles during irritation of the LH in the absence of food is an example of advancing type reaction. The increase of level of alimentary motivation, arising at threshold irritation of the LH of rabbits under the conditions of hunger and satiety during the resultant food-intake behavior, increased frequency of generation of bursts of AP in a phase of the capture of food, but did not influence on this indicator in a phase of chewing of food. The received results testify about descending stimulating influences of alimentary motivational excitation on neurons of the chewing centre in medulla and on impulse activity of chewing muscles.

Sensitivity to binaural timing in bilateral cochlear implant users.

PubMed

van Hoesel, Richard J M

2007-04-01

Various measures of binaural timing sensitivity were made in three bilateral cochlear implant users, who had demonstrated moderate-to-good interaural time delay (ITD) sensitivity at 100 pulses-per-second (pps). Overall, ITD thresholds increased at higher pulse rates, lower levels, and shorter durations, although intersubject differences were evident. Monaural rate-discrimination thresholds, using the same stimulation parameters, showed more substantial elevation than ITDs with increased rate. ITD sensitivity with 6000 pps stimuli, amplitude-modulated at 100 Hz, was similar to that with unmodulated pulse trains at 100 pps, but at 200 and 300 Hz performance was poorer than with unmodulated signals. Measures of sensitivity to binaural beats with unmodulated pulse-trains showed that all three subjects could use time-varying ITD cues at 100 pps, but not 300 pps, even though static ITD sensitivity was relatively unaffected over that range. The difference between static and dynamic ITD thresholds is discussed in terms of relative contributions from initial and later arriving cues, which was further examined in an experiment using two-pulse stimuli as a function of interpulse separation. In agreement with the binaural-beat data, findings from that experiment showed poor discrimination of ITDs on the second pulse when the interval between pulses was reduced to a few milliseconds.

Using a coherent hydrophone array for observing sperm whale range, classification, and shallow-water dive profiles.

PubMed

Tran, Duong D; Huang, Wei; Bohn, Alexander C; Wang, Delin; Gong, Zheng; Makris, Nicholas C; Ratilal, Purnima

2014-06-01

Sperm whales in the New England continental shelf and slope were passively localized, in both range and bearing, and classified using a single low-frequency (<2500 Hz), densely sampled, towed horizontal coherent hydrophone array system. Whale bearings were estimated using time-domain beamforming that provided high coherent array gain in sperm whale click signal-to-noise ratio. Whale ranges from the receiver array center were estimated using the moving array triangulation technique from a sequence of whale bearing measurements. Multiple concurrently vocalizing sperm whales, in the far-field of the horizontal receiver array, were distinguished and classified based on their horizontal spatial locations and the inter-pulse intervals of their vocalized click signals. The dive profile was estimated for a sperm whale in the shallow waters of the Gulf of Maine with 160 m water-column depth located close to the array's near-field where depth estimation was feasible by employing time difference of arrival of the direct and multiply reflected click signals received on the horizontal array. By accounting for transmission loss modeled using an ocean waveguide-acoustic propagation model, the sperm whale detection range was found to exceed 60 km in low to moderate sea state conditions after coherent array processing.

Evolution of divergent female mating preference in response to experimental sexual selection.

PubMed

Debelle, Allan; Ritchie, Michael G; Snook, Rhonda R

2014-09-01

Sexual selection is predicted to drive the coevolution of mating signals and preferences (mating traits) within populations, and could play a role in speciation if sexual isolation arises due to mating trait divergence between populations. However, few studies have demonstrated that differences in mating traits between populations result from sexual selection alone. Experimental evolution is a promising approach to directly examine the action of sexual selection on mating trait divergence among populations. We manipulated the opportunity for sexual selection (low vs. high) in populations of Drosophila pseudoobscura. Previous studies on these experimental populations have shown that sexual selection manipulation resulted in the divergence between sexual selection treatments of several courtship song parameters, including interpulse interval (IPI) which markedly influences male mating success. Here, we measure female preference for IPI using a playback design to test for preference divergence between the sexual selection treatments after 130 generations of experimental sexual selection. The results suggest that female preference has coevolved with male signal, in opposite directions between the sexual selection treatments, providing direct evidence of the ability of sexual selection to drive the divergent coevolution of mating traits between populations. We discuss the implications in the context sexual selection and speciation. © 2014 The Authors. Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Multi-channel acoustic recording and automated analysis of Drosophila courtship songs

PubMed Central

2013-01-01

Background Drosophila melanogaster has served as a powerful model system for genetic studies of courtship songs. To accelerate research on the genetic and neural mechanisms underlying courtship song, we have developed a sensitive recording system to simultaneously capture the acoustic signals from 32 separate pairs of courting flies as well as software for automated segmentation of songs. Results Our novel hardware design enables recording of low amplitude sounds in most laboratory environments. We demonstrate the power of this system by collecting, segmenting and analyzing over 18 hours of courtship song from 75 males from five wild-type strains of Drosophila melanogaster. Our analysis reveals previously undetected modulation of courtship song features and extensive natural genetic variation for most components of courtship song. Despite having a large dataset with sufficient power to detect subtle modulations of song, we were unable to identify previously reported periodic rhythms in the inter-pulse interval of song. We provide detailed instructions for assembling the hardware and for using our open-source segmentation software. Conclusions Analysis of a large dataset of acoustic signals from Drosophila melanogaster provides novel insight into the structure and dynamics of species-specific courtship songs. Our new system for recording and analyzing fly acoustic signals should therefore greatly accelerate future studies of the genetics, neurobiology and evolution of courtship song. PMID:23369160

Optimal size of stochastic Hodgkin-Huxley neuronal systems for maximal energy efficiency in coding pulse signals.

PubMed

Yu, Lianchun; Liu, Liwei

2014-03-01

The generation and conduction of action potentials (APs) represents a fundamental means of communication in the nervous system and is a metabolically expensive process. In this paper, we investigate the energy efficiency of neural systems in transferring pulse signals with APs. By analytically solving a bistable neuron model that mimics the AP generation with a particle crossing the barrier of a double well, we find the optimal number of ion channels that maximizes the energy efficiency of a neuron. We also investigate the energy efficiency of a neuron population in which the input pulse signals are represented with synchronized spikes and read out with a downstream coincidence detector neuron. We find an optimal number of neurons in neuron population, as well as the number of ion channels in each neuron that maximizes the energy efficiency. The energy efficiency also depends on the characters of the input signals, e.g., the pulse strength and the interpulse intervals. These results are confirmed by computer simulation of the stochastic Hodgkin-Huxley model with a detailed description of the ion channel random gating. We argue that the tradeoff between signal transmission reliability and energy cost may influence the size of the neural systems when energy use is constrained.

Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind braille readers.

PubMed

Bhattacharjee, Arindam; Ye, Amanda J; Lisak, Joy A; Vargas, Maria G; Goldreich, Daniel

2010-10-27

Braille reading is a demanding task that requires the identification of rapidly varying tactile patterns. During proficient reading, neighboring characters impact the fingertip at ∼100 ms intervals, and adjacent raised dots within a character at 50 ms intervals. Because the brain requires time to interpret afferent sensorineural activity, among other reasons, tactile stimuli separated by such short temporal intervals pose a challenge to perception. How, then, do proficient Braille readers successfully interpret inputs arising from their fingertips at such rapid rates? We hypothesized that somatosensory perceptual consolidation occurs more rapidly in proficient Braille readers. If so, Braille readers should outperform sighted participants on masking tasks, which demand rapid perceptual processing, but would not necessarily outperform the sighted on tests of simple vibrotactile sensitivity. To investigate, we conducted two-interval forced-choice vibrotactile detection, amplitude discrimination, and masking tasks on the index fingertips of 89 sighted and 57 profoundly blind humans. Sighted and blind participants had similar unmasked detection (25 ms target tap) and amplitude discrimination (compared with 100 μm reference tap) thresholds, but congenitally blind Braille readers, the fastest readers among the blind participants, exhibited significantly less masking than the sighted (masker, 50 Hz, 50 μm; target-masker delays, ±50 and ±100 ms). Indeed, Braille reading speed correlated significantly and specifically with masking task performance, and in particular with the backward masking decay time constant. We conclude that vibrotactile sensitivity is unchanged but that perceptual processing is accelerated in congenitally blind Braille readers.

Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind Braille readers

PubMed Central

Bhattacharjee, Arindam; Ye, Amanda J.; Lisak, Joy A.; Vargas, Maria G.; Goldreich, Daniel

2010-01-01

Braille reading is a demanding task that requires the identification of rapidly varying tactile patterns. During proficient reading, neighboring characters impact the fingertip at about 100-ms intervals, and adjacent raised dots within a character at 50-ms intervals. Because the brain requires time to interpret afferent sensorineural activity, among other reasons, tactile stimuli separated by such short temporal intervals pose a challenge to perception. How, then, do proficient Braille readers successfully interpret inputs arising from their fingertips at such rapid rates? We hypothesized that somatosensory perceptual consolidation occurs more rapidly in proficient Braille readers. If so, Braille readers should outperform sighted participants on masking tasks, which demand rapid perceptual processing, but would not necessarily outperform the sighted on tests of simple vibrotactile sensitivity. To investigate, we conducted two-interval forced-choice vibrotactile detection, amplitude discrimination, and masking tasks on the index fingertips of 89 sighted and 57 profoundly blind humans. Sighted and blind participants had similar unmasked detection (25-ms target tap) and amplitude discrimination (compared to 100-micron reference tap) thresholds, but congenitally blind Braille readers, the fastest readers among the blind participants, exhibited significantly less masking than the sighted (masker: 50-Hz, 50-micron; target-masker delays ±50 and ±100 ms). Indeed, Braille reading speed correlated significantly and specifically with masking task performance, and in particular with the backward masking decay time constant. We conclude that vibrotactile sensitivity is unchanged, but that perceptual processing is accelerated in congenitally blind Braille readers. PMID:20980584

Dynamical analysis of the avian-human influenza epidemic model using the semi-analytical method

NASA Astrophysics Data System (ADS)

Jabbari, Azizeh; Kheiri, Hossein; Bekir, Ahmet

2015-03-01

In this work, we present a dynamic behavior of the avian-human influenza epidemic model by using efficient computational algorithm, namely the multistage differential transform method(MsDTM). The MsDTM is used here as an algorithm for approximating the solutions of the avian-human influenza epidemic model in a sequence of time intervals. In order to show the efficiency of the method, the obtained numerical results are compared with the fourth-order Runge-Kutta method (RK4M) and differential transform method(DTM) solutions. It is shown that the MsDTM has the advantage of giving an analytical form of the solution within each time interval which is not possible in purely numerical techniques like RK4M.

The combined effects of forward masking by noise and high click rate on monaural and binaural human auditory nerve and brainstem potentials.

PubMed

Pratt, Hillel; Polyakov, Andrey; Bleich, Naomi; Mittelman, Naomi

2004-07-01

To study effects of forward masking and rapid stimulation on human monaurally- and binaurally-evoked brainstem potentials and suggest their relation to synaptic fatigue and recovery and to neuronal action potential refractoriness. Auditory brainstem evoked potentials (ABEPs) were recorded from 12 normally- and symmetrically hearing adults, in response to each click (50 dB nHL, condensation and rarefaction) in a train of nine, with an inter-click interval of 11 ms, that followed a white noise burst of 100 ms duration (50 dB nHL). Sequences of white noise and click train were repeated at a rate of 2.89 s(-1). The interval between noise and first click in the train was 2, 11, 22, 44, 66 or 88 ms in different runs. ABEPs were averaged (8000 repetitions) using a dwell time of 25 micros/address/channel. The binaural interaction components (BICs) of ABEPs were derived and the single, centrally located equivalent dipoles of ABEP waves I and V and of the BIC major wave were estimated. The latencies of dipoles I and V of ABEP, their inter-dipole interval and the dipole magnitude of component V were significantly affected by the interval between noise and clicks and by the serial position of the click in the train. The latency and dipole magnitude of the major BIC component were significantly affected by the interval between noise and clicks. Interval from noise and the click's serial position in the train interacted to affect dipole V latency, dipole V magnitude, BIC latencies and the V-I inter-dipole latency difference. Most of the effects were fully apparent by the first few clicks in the train, and the trend (increase or decrease) was affected by the interval between noise and clicks. The changes in latency and magnitude of ABEP and BIC components with advancing position in the click train and the interactions of click position in the train with the intervals from noise indicate an interaction of fatigue and recovery, compatible with synaptic depletion and replenishing, respectively. With the 2 ms interval between noise and the first click in the train, neuronal action potential refractoriness may also be involved.

Cardiovascular Autonomic Dysfunction in Patients with Morbid Obesity

PubMed Central

de Sant Anna Junior, Maurício; Carneiro, João Regis Ivar; Carvalhal, Renata Ferreira; Torres, Diego de Faria Magalhães; da Cruz, Gustavo Gavina; Quaresma, José Carlos do Vale; Lugon, Jocemir Ronaldo; Guimarães, Fernando Silva

2015-01-01

Background Morbid obesity is directly related to deterioration in cardiorespiratory capacity, including changes in cardiovascular autonomic modulation. Objective This study aimed to assess the cardiovascular autonomic function in morbidly obese individuals. Methods Cross-sectional study, including two groups of participants: Group I, composed by 50 morbidly obese subjects, and Group II, composed by 30 nonobese subjects. The autonomic function was assessed by heart rate variability in the time domain (standard deviation of all normal RR intervals [SDNN]; standard deviation of the normal R-R intervals [SDNN]; square root of the mean squared differences of successive R-R intervals [RMSSD]; and the percentage of interval differences of successive R-R intervals greater than 50 milliseconds [pNN50] than the adjacent interval), and in the frequency domain (high frequency [HF]; low frequency [LF]: integration of power spectral density function in high frequency and low frequency ranges respectively). Between-group comparisons were performed by the Student’s t-test, with a level of significance of 5%. Results Obese subjects had lower values of SDNN (40.0 ± 18.0 ms vs. 70.0 ± 27.8 ms; p = 0.0004), RMSSD (23.7 ± 13.0 ms vs. 40.3 ± 22.4 ms; p = 0.0030), pNN50 (14.8 ± 10.4 % vs. 25.9 ± 7.2%; p = 0.0061) and HF (30.0 ± 17.5 Hz vs. 51.7 ± 25.5 Hz; p = 0.0023) than controls. Mean LF/HF ratio was higher in Group I (5.0 ± 2.8 vs. 1.0 ± 0.9; p = 0.0189), indicating changes in the sympathovagal balance. No statistical difference in LF was observed between Group I and Group II (50.1 ± 30.2 Hz vs. 40.9 ± 23.9 Hz; p = 0.9013). Conclusion morbidly obese individuals have increased sympathetic activity and reduced parasympathetic activity, featuring cardiovascular autonomic dysfunction. PMID:26536979

Impact of transforming growth factor-beta1 on atrioventricular node conduction modification by injected autologous fibroblasts in the canine heart.

PubMed

Bunch, T Jared; Mahapatra, Srijoy; Bruce, G Keith; Johnson, Susan B; Miller, Dylan V; Horne, Benjamin D; Wang, Xiao-Li; Lee, Hon-Chi; Caplice, Noel M; Packer, Douglas L

2006-05-30

Atrioventricular (AV) nodal ablation for management of atrial fibrillation (AF) is irreversible and requires permanent pacemaker implantation. We hypothesized that as an alternative, implantation of autologous fibroblasts in the perinodal region would focally modify AV nodal conduction and that this modulation would be enhanced by pretreatment with transforming growth factor-beta1 (TGF-beta1), a stimulant of fibroblasts. Skin biopsies were taken from 12 mongrel dogs, and derived fibroblasts were dissociated and grown in culture for 2 weeks. Multiple injections (0.25 mL) were made through an 8F NOGA catheter along the fast/slow AV nodal pathways as guided by an electroanatomic mapping system. Seven dogs received fibroblasts alone (1x10(6) cells/mL), 7 dogs received TGF-beta1 (5 microg), 4 dogs received fibroblasts and TGF-beta1 (1x10(6) cells/mL+5 microg), and 4 dogs received saline only. AV node function was assessed at baseline and after 4 weeks. Saline (80 mL) with assigned therapy (0.25 mL per injection) was injected into the peri-AV nodal region in each dog. At baseline, the AH interval (66+/-3 ms) and the average RR interval (331+/-17 ms) in pacing-induced AF were similar in each cohort. The increase in AH interval in normal sinus rhythm was longer after fibroblast (23+/-4 versus 5+/-5 ms; P=0.05) and fibroblast plus TGF-beta1 (50+/-5 versus 5+/-5 ms; P<0.001) injections than with saline alone, with similar findings during high right atrium and distal coronary sinus pacing. The AH interval was not significantly increased after TGF-beta1 injections. The AH interval was significantly longer after fibroblast plus TGF-beta1 injections than with either therapy (TGF-beta1 or fibroblasts) alone. The RR interval during AF was increased in dogs that received fibroblasts alone (110+/-36 versus -41+/-34 ms) and to a greater extent with the addition of TGF-beta1 (294+/-108 versus -41+/-34 ms). No AV block was seen in any cohort at 4 weeks. Labeled fibroblasts that expressed vimentin were identified in all dogs that received cell injections at 4 weeks. AV nodal modification can be achieved with injected fibroblasts without the creation of AV block. The effect on AV node conduction is substantially enhanced by pretreatment of fibroblasts with TGF-beta1. These data have therapeutic potential for the management of rapid ventricular rate during AF without pacemaker implantation.

Comparison of timing and force control of foot tapping between elderly and young subjects.

PubMed

Takimoto, Koji; Takebayashi, Hideaki; Miyamoto, Kenzo; Takuma, Yutaka; Inoue, Yoshikazu; Miyamoto, Shoko; Okabe, Takao; Okuda, Takahiro; Kaba, Hideto

2016-06-01

[Purpose] To examine the ability of young and elderly individuals to control the timing and force of periodic sequential foot tapping. [Subjects and Methods] Participants were 10 young (age, 22.1 ± 4.3 years) and 10 elderly individuals (74.8 ± 6.7 years) who were healthy and active. The foot tapping task consisted of practice (stimulus-synchronized tapping with visual feedback) and recall trials (self-paced tapping without visual feedback), periodically performed in this order, at 500-, 1,000-, and 2,000-ms target interstimulus-onset intervals, with a target force of 20% maximum voluntary contraction of the ankle plantar-flexor muscle. [Results] The coefficients of variation of force and intertap interval, used for quantifying the steadiness of the trials, were significantly greater in the elderly than in the young individuals. At the 500-ms interstimulus-onset interval, age-related effects were observed on the normalized mean absolute error of force, which was used to quantify the accuracy of the trials. The coefficients of variation of intertap interval for elderly individuals were significantly greater in the practice than in the recall trials at the 500- and 1,000-ms interstimulus-onset intervals. [Conclusion] The elderly individuals exhibited greater force and timing variability than the young individuals and showed impaired visuomotor processing during foot tapping sequences.

[Estimation of the atrioventricular time interval by pulse Doppler in the normal fetal heart].

PubMed

Hamela-Olkowska, Anita; Dangel, Joanna

2009-08-01

To assess normative values of the fetal atrioventricular (AV) time interval by pulse-wave Doppler methods on 5-chamber view. Fetal echocardiography exams were performed using Acuson Sequoia 512 in 140 singleton fetuses at 18 to 40 weeks of gestation with sinus rhythm and normal cardiac and extracardiac anatomy. Pulsed Doppler derived AV intervals were measured from left ventricular inflow/outflow view using transabdominal convex 3.5-6 MHz probe. The values of AV time interval ranged from 100 to 150 ms (mean 123 +/- 11.2). The AV interval was negatively correlated with the heart rhythm (p<0.001). Fetal heart rate decreased as gestation progressed (p<0.001). Thus, the AV intervals increased with the age of gestation (p=0.007). However, in the same subgroup of the fetal heart rate there was no relation between AV intervals and gestational age. Therefore, the AV intervals showed only the heart rate dependence. The 95th percentiles of AV intervals according to FHR ranged from 135 to 148 ms. 1. The AV interval duration was negatively correlated with the heart rhythm. 2. Measurement of AV time interval is easy to perform and has a good reproducibility. It may be used for the fetal heart block screening in anti-Ro and anti-La positive pregnancies. 3. Normative values established in the study may help obstetricians in assessing fetal abnormalities of the AV conduction.

A fast BK-type KCa current acts as a postsynaptic modulator of temporal selectivity for communication signals.

PubMed

Kohashi, Tsunehiko; Carlson, Bruce A

2014-01-01

Temporal patterns of spiking often convey behaviorally relevant information. Various synaptic mechanisms and intrinsic membrane properties can influence neuronal selectivity to temporal patterns of input. However, little is known about how synaptic mechanisms and intrinsic properties together determine the temporal selectivity of neuronal output. We tackled this question by recording from midbrain electrosensory neurons in mormyrid fish, in which the processing of temporal intervals between communication signals can be studied in a reduced in vitro preparation. Mormyrids communicate by varying interpulse intervals (IPIs) between electric pulses. Within the midbrain posterior exterolateral nucleus (ELp), the temporal patterns of afferent spike trains are filtered to establish single-neuron IPI tuning. We performed whole-cell recording from ELp neurons in a whole-brain preparation and examined the relationship between intrinsic excitability and IPI tuning. We found that spike frequency adaptation of ELp neurons was highly variable. Postsynaptic potentials (PSPs) of strongly adapting (phasic) neurons were more sharply tuned to IPIs than weakly adapting (tonic) neurons. Further, the synaptic filtering of IPIs by tonic neurons was more faithfully converted into variation in spiking output, particularly at short IPIs. Pharmacological manipulation under current- and voltage-clamp revealed that tonic firing is mediated by a fast, large-conductance Ca(2+)-activated K(+) (KCa) current (BK) that speeds up action potential repolarization. These results suggest that BK currents can shape the temporal filtering of sensory inputs by modifying both synaptic responses and PSP-to-spike conversion. Slow SK-type KCa currents have previously been implicated in temporal processing. Thus, both fast and slow KCa currents can fine-tune temporal selectivity.

Efficient Intracellular Delivery of Molecules with High Cell Viability Using Nanosecond-Pulsed Laser-Activated Carbon Nanoparticles

PubMed Central

2015-01-01

Conventional physical and chemical methods that efficiently deliver molecules into cells are often associated with low cell viability. In this study, we evaluated the cellular effects of carbon nanoparticles believed to emit photoacoustic waves due to nanosecond-pulse laser activation to test the hypothesis that this method could achieve efficient intracellular delivery while maintaining high cell viability. Suspensions of DU145 human prostate carcinoma cells, carbon black (CB) nanoparticles, and calcein were exposed to 5–9 ns long laser pulses of near-infrared (1064 nm wavelength) light and then analyzed by flow cytometry for intracellular uptake of calcein and cell viability by propidium iodide staining. We found that intracellular uptake increased and in some cases saturated at high levels with only small losses in cell viability as a result of increasing laser fluence, laser exposure time, and as a unifying parameter, the total laser energy. Changing interpulse spacing between 0.1 and 10 s intervals showed no significant change in bioeffects, suggesting that the effects of each pulse were independent when spaced by at least 0.1 s intervals. Pretreatment of CB nanoparticles to intense laser exposure followed by mixing with cells also had no significant effect on uptake or viability. Similar uptake and viability were seen when CB nanoparticles were substituted with India ink, when DU145 cells were substituted with H9c2 rat cardiomyoblast cells, and when calcein was substituted with FITC-dextran. The best laser exposure conditions tested led to 88% of cells with intracellular uptake and close to 100% viability, indicating that nanosecond-pulse laser-activated carbon nanoparticles can achieve efficient intracellular delivery while maintaining high cell viability. PMID:24547946

Detecting REM sleep from the finger: an automatic REM sleep algorithm based on peripheral arterial tone (PAT) and actigraphy.

PubMed

Herscovici, Sarah; Pe'er, Avivit; Papyan, Surik; Lavie, Peretz

2007-02-01

Scoring of REM sleep based on polysomnographic recordings is a laborious and time-consuming process. The growing number of ambulatory devices designed for cost-effective home-based diagnostic sleep recordings necessitates the development of a reliable automatic REM sleep detection algorithm that is not based on the traditional electroencephalographic, electrooccolographic and electromyographic recordings trio. This paper presents an automatic REM detection algorithm based on the peripheral arterial tone (PAT) signal and actigraphy which are recorded with an ambulatory wrist-worn device (Watch-PAT100). The PAT signal is a measure of the pulsatile volume changes at the finger tip reflecting sympathetic tone variations. The algorithm was developed using a training set of 30 patients recorded simultaneously with polysomnography and Watch-PAT100. Sleep records were divided into 5 min intervals and two time series were constructed from the PAT amplitudes and PAT-derived inter-pulse periods in each interval. A prediction function based on 16 features extracted from the above time series that determines the likelihood of detecting a REM epoch was developed. The coefficients of the prediction function were determined using a genetic algorithm (GA) optimizing process tuned to maximize a price function depending on the sensitivity, specificity and agreement of the algorithm in comparison with the gold standard of polysomnographic manual scoring. Based on a separate validation set of 30 patients overall sensitivity, specificity and agreement of the automatic algorithm to identify standard 30 s epochs of REM sleep were 78%, 92%, 89%, respectively. Deploying this REM detection algorithm in a wrist worn device could be very useful for unattended ambulatory sleep monitoring. The innovative method of optimization using a genetic algorithm has been proven to yield robust results in the validation set.

Effects of practice on variability in an isochronous serial interval production task: asymptotical levels of tapping variability after training are similar to those of musicians.

PubMed

Madison, Guy; Karampela, Olympia; Ullén, Fredrik; Holm, Linus

2013-05-01

Timing permeates everyday activities such as walking, dancing and music, yet the effect of short-term practice in this ubiquitous activity is largely unknown. In two training experiments involving sessions spread across several days, we examined short-term practice effects on timing variability in a sequential interval production task. In Experiment 1, we varied the mode of response (e.g., drumstick and finger tapping) and the level of sensory feedback. In Experiment 2 we varied the interval in 18 levels ranging from 500 ms to 1624 ms. Both experiments showed a substantial decrease in variability within the first hour of practice, but little thereafter. This effect was similar across mode of response, amount of feedback, and interval duration, and was manifested as a reduction in both local variability (between neighboring intervals) and drift (fluctuation across multiple intervals). The results suggest mainly effects on motor implementation rather than on cognitive timing processes, and have methodological implications for timing studies that have not controlled for practice. Copyright © 2013 Elsevier B.V. All rights reserved.

Measurement of spin-lattice relaxation times and concentrations in systems with chemical exchange using the one-pulse sequence: breakdown of the Ernst model for partial saturation in nuclear magnetic resonance spectroscopy.

PubMed

Spencer, R G; Fishbein, K W

2000-01-01

A fundamental problem in Fourier transform NMR spectroscopy is the calculation of observed resonance amplitudes for a repetitively pulsed sample, as first analyzed by Ernst and Anderson in 1966. Applications include determination of spin-lattice relaxation times (T(1)'s) by progressive saturation and correction for partial saturation in order to determine the concentrations of the chemical constituents of a spectrum. Accordingly, the Ernst and Anderson formalism has been used in innumerable studies of chemical and, more recently, physiological systems. However, that formalism implicitly assumes that no chemical exchange occurs. Here, we present an analysis of N sites in an arbitrary chemical exchange network, explicitly focusing on the intermediate exchange rate regime in which the spin-lattice relaxation rates and the chemical exchange rates are comparable in magnitude. As a special case of particular importance, detailed results are provided for a system with three sites undergoing mutual exchange. Specific properties of the N-site network are then detailed. We find that (i) the Ernst and Anderson analysis describing the response of a system to repetitive pulsing is inapplicable to systems with chemical exchange and can result in large errors in T(1) and concentration measurements; (ii) T(1)'s for systems with arbitrary exchange networks may still be correctly determined from a one-pulse experiment using the Ernst formula, provided that a short interpulse delay time and a large flip angle are used; (iii) chemical concentrations for exchanging systems may be correctly determined from a one-pulse experiment either by using a short interpulse delay time with a large flip angle, as for measuring T(1)'s, and correcting for partial saturation by use of the Ernst formula, or directly by using a long interpulse delay time to avoid saturation; (iv) there is a significant signal-to-noise penalty for performing one-pulse experiments under conditions which permit accurate measurements of T(1)'s and chemical concentrations. The present results are analogous to but are much more general than those that we have previously derived for systems with two exchanging sites. These considerations have implications for the design and interpretation of one-pulse experiments for all systems exhibiting chemical exchange in the intermediate exchange regime, including virtually all physiologic samples.

Motor Synchronization in Patients With Schizophrenia: Preserved Time Representation With Abnormalities in Predictive Timing.

PubMed

Wilquin, Hélène; Delevoye-Turrell, Yvonne; Dione, Mariama; Giersch, Anne

2018-01-01

Objective: Basic temporal dysfunctions have been described in patients with schizophrenia, which may impact their ability to connect and synchronize with the outer world. The present study was conducted with the aim to distinguish between interval timing and synchronization difficulties and more generally the spatial-temporal organization disturbances for voluntary actions. A new sensorimotor synchronization task was developed to test these abilities. Method: Twenty-four chronic schizophrenia patients matched with 27 controls performed a spatial-tapping task in which finger taps were to be produced in synchrony with a regular metronome to six visual targets presented around a virtual circle on a tactile screen. Isochronous (time intervals of 500 ms) and non-isochronous auditory sequences (alternated time intervals of 300/600 ms) were presented. The capacity to produce time intervals accurately versus the ability to synchronize own actions (tap) with external events (tone) were measured. Results: Patients with schizophrenia were able to produce the tapping patterns of both isochronous and non-isochronous auditory sequences as accurately as controls producing inter-response intervals close to the expected interval of 500 and 900 ms, respectively. However, the synchronization performances revealed significantly more positive asynchrony means (but similar variances) in the patient group than in the control group for both types of auditory sequences. Conclusion: The patterns of results suggest that patients with schizophrenia are able to perceive and produce both simple and complex sequences of time intervals but are impaired in the ability to synchronize their actions with external events. These findings suggest a specific deficit in predictive timing, which may be at the core of early symptoms previously described in schizophrenia.

Evaluating dedicated and intrinsic models of temporal encoding by varying context

PubMed Central

Spencer, Rebecca M.C.; Karmarkar, Uma; Ivry, Richard B.

2009-01-01

Two general classes of models have been proposed to account for how people process temporal information in the milliseconds range. Dedicated models entail a mechanism in which time is explicitly encoded; examples include clock–counter models and functional delay lines. Intrinsic models, such as state-dependent networks (SDN), represent time as an emergent property of the dynamics of neural processing. An important property of SDN is that the encoding of duration is context dependent since the representation of an interval will vary as a function of the initial state of the network. Consistent with this assumption, duration discrimination thresholds for auditory intervals spanning 100 ms are elevated when an irrelevant tone is presented at varying times prior to the onset of the test interval. We revisit this effect in two experiments, considering attentional issues that may also produce such context effects. The disruptive effect of a variable context was eliminated or attenuated when the intervals between the irrelevant tone and test interval were made dissimilar or the duration of the test interval was increased to 300 ms. These results indicate how attentional processes can influence the perception of brief intervals, as well as point to important constraints for SDN models. PMID:19487188

Single therapeutic and supratherapeutic doses of corifollitropin alfa, a sustained follicle stimulant, do not prolong the QTcF-interval in healthy postmenopausal volunteers.

PubMed

de Kam, Pieter-Jan; van Kuijk, Jacqueline H M; Zandvliet, Anthe S; Thomsen, Torben

2015-09-01

Corifollitropin alfa (Elonva®) is the first hybrid follicle-stimulating hormone molecule with demonstrated sustained follicle-stimulating activity after a single subcutaneous injection. This trial evaluated if corifollitropin alfa is associated with QT/QTc prolongation and/ or proarrhythmic potential as compared to placebo in healthy post-menopausal women. Participants were healthy, postmenopausal women. Study treatments were corifollitropin alfa 150 μg, corifollitropin alfa 240 μg, and moxifloxacin 400 mg with placebo. This randomized, double blind, double-dummy, 4-period crossover trial compared single doses of corifollitropin alfa 150 μg (therapeutic dose), corifollitropin alfa 240 μg (supratherapeutic dose), and moxifloxacin 400 mg (positive control) with placebo. Corifollitropin alfa was administered on day 1 and moxifloxacin on day 2. The largest time-matched mean QTcF difference versus placebo for the therapeutic dose of corifollitropin alfa was 1.4 ms (upper limit of 1-sided 95% confidence interval (UL 95% CI) = 3.4 ms), and for the supratherapeutic dose was 1.2 ms (UL 95% CI = 3.6 ms). For both the therapeutic and the supratherapeutic dose of corifollitropin alfa and at all time points, the UL 95% CI for the time matched QTcF differences compared with placebo was below 10 ms, the threshold of relevance defined by the ICH E14 guideline. Single therapeutic and supratherapeutic doses of corifollitropin alfa are not associated with clinically relevant QT/QTc-interval prolongation in healthy post-menopausal women.

The Effects of Continuous One-Arm Kettlebell Swing Training on Physiological Parameters in United States Air Force Personnel: A Pilot Study

DTIC Science & Technology

2016-11-01

collegiate soccer players . KB snatches were performed 3 days per week for 20 minutes with 15-second work-to-rest intervals, while the control group...10] used KB weights that were 18% of total body mass and reported a 6% improvement in aerobic capacity in women’s collegiate soccer players who...Force Personnel: A Pilot Study Molly Wade, MS; Reginald O’Hara, PhD; Lydia Caldwell, MS; Jason Ordway, MS; Darryn Bryant, MS

Temporal-Spectral Characterization and Classification of Marine Mammal Vocalizations and Diesel-Electric Ships Radiated Sound over Continental Shelf Scale Regions with Coherent Hydrophone Array Measurements

NASA Astrophysics Data System (ADS)

Huang, Wei

The passive ocean acoustic waveguide remote sensing (POAWRS) technology is capable of monitoring a large variety of underwater sound sources over instantaneous wide areas spanning continental-shelf scale regions. POAWRS uses a large-aperture densely-sampled coherent hydrophone array to significantly enhance the signal-to-noise ratio via beamforming, enabling detection of sound sources roughly two-orders of magnitude more distant in range than that possible with a single hydrophone. The sound sources detected by POAWRS include ocean biology, geophysical processes, and man-made activities. POAWRS provides detection, bearing-time estimation, localization, and classification of underwater sound sources. The volume of underwater sounds detected by POAWRS is immense, typically exceeding a million unique signal detections per day, in the 10-4000 Hz frequency range, making it a tremendously challenging task to distinguish and categorize the various sound sources present in a given region. Here we develop various approaches for characterizing and clustering the signal detections for various subsets of data acquired using the POAWRS technology. The approaches include pitch tracking of the dominant signal detections, time-frequency feature extraction, clustering and categorization methods. These approaches are essential for automatic processing and enhancing the efficiency and accuracy of POAWRS data analysis. The results of the signal detection, clustering and classification analysis are required for further POAWRS processing, including localization and tracking of a large number of oceanic sound sources. Here the POAWRS detection, localization and clustering approaches are applied to analyze and elucidate the vocalization behavior of humpback, sperm and fin whales in the New England continental shelf and slope, including the Gulf of Maine from data acquired using coherent hydrophone arrays. The POAWRS technology can also be applied for monitoring ocean vehicles. Here the approach is calibrated by application to known ships present in the Gulf of Maine and in the Norwegian Sea from their underwater sounds received using a coherent hydrophone array. The vocalization behavior of humpback whales was monitored over vast areas of the Gulf of Maine using the POAWRS technique over multiple diel cycles in Fall 2006. The humpback vocalizations, received at a rate of roughly 1800+/-1100 calls per day, comprised of both song and non-song. The song vocalizations, composed of highly structured and repeatable set of phrases, are characterized by inter-pulse intervals of 3.5 +/- 1.8 s. Songs were detected throughout the diel cycle, occuring roughly 40% during the day and 60% during the night. The humpback non-song vocalizations, dominated by shorter duration (≤3 s) downsweep and bow-shaped moans, as well as a small fraction of longer duration (˜5 s) cries, have significantly larger mean and more variable inter-pulse intervals of 14.2 +/- 11 s. The non-song vocalizations were detected at night with negligible detections during the day, implying they probably function as nighttime communication signals. The humpback song and non-song vocalizations are separately localized using the moving array triangulation and array invariant techniques. The humpback song and non-song moan calls are both consistently localized to a dense area on northeastern Georges Bank and a less dense region extended from Franklin Basin to the Great South Channel. Humpback cries occur exclusively on northeastern Georges Bank and during nights with coincident dense Atlantic herring shoaling populations, implying the cries are feeding-related. Sperm whales in the New England continental shelf and slope were passively localized and classified from their vocalizations received using a single low-frequency (<2500 Hz) densely-sampled horizontal coherent hydrophone array deployed in Spring 2013 in Gulf of Maine. Whale bearings were estimated using time-domain beamforming that provided high coherent array gain in sperm whale click signal-to-noise ratio. Whale ranges from the receiver array center were estimated using the moving array triangulation technique from a sequence of whale bearing measurements. Multiple concurrently vocalizing sperm whales, in the far-field of the horizontal receiver array, were distinguished and classified based on their horizontal spatial locations and the inter-pulse intervals of their vocalized click signals. We provide detailed analysis of over 15,000 fin whale 20 Hz vocalizations received on Oct 1-3, 2006 in the Gulf of Maine. These vocalizations are separated into 16 clusters following the clustering approaches. Seven of these types are prominent, each acounting for between 8% to 16% and together comprise roughly 85% of all the analyzed vocalizations. The 7 prominent clusters are each more abundant during nighttime hours by a factor of roughly 2.5 times than that of the daytime. The diel-spatial correlation of the 7 prominent clusters to the simultaneously observed densities of their fish prey, the Atlantic herring in the Gulf of Maine, is provided which implies that the factor of roughly 2.5 increase in call rate during night-time hours can be attributed to increased fish-feeding activities. (Abstract shortened by ProQuest.).

Assessment of atrial electromechanical interval and P wave dispersion in patients with polycystic ovary syndrome.

PubMed

Bayır, Pınar Türker; Güray, Ümit; Duyuler, Serkan; Demirkan, Burcu; Kayaalp, Oya; Kanat, Selçuk; Güray, Yeşim

2016-02-01

Polycystic ovary syndrome (PCOS) is associated with increased cardiovascular risk, including ischemic stroke. Prolonged atrial electromechanical interval (EMI) is related to increased atrial fibrillation (AF) risk. The aim of the study is to evaluate atrial EMI and electrocardiographic P-wave indices related to increased AF risk in patients with PCOS. Forty PCOS patients diagnosed on the basis of the Rotterdam criteria and 20 age-matched controls were prospectively included. patients with atrioventricular or intraventricular conduction abnormalities, dysrhythmia or taking antiarrhythmic drugs, atherosclerotic heart disease, cardiomyopathies, valvular lesions, pericardial disease, a history of pulmonary emboli or pulmonary hypertension, and abnormal thyroid function were excluded. Intra and interatrial EMI were measured by tissue Doppler imaging and P-wave dispersion (Pd) was calculated on 12-lead electrocardiography (ECG). The Isovolumetric relaxation time was the interval between the aortic valve closure artifact at the end of the LV outflow envelope and the mitral valve opening artifact at the beginning of the mitral E wave. Patients with PCOS had significantly higher interatrial [38 (24-65) ms vs. 16 (9-19) ms p<0.001], left-sided intra-atrial (14.8±6.1 vs. 7±1.7 ms, p<0.001), and right-sided intra-atrial (22.3±8.1 vs. 8.6±3.6 ms, p<0.001) EMI compared with the control group. Pd was significantly greater in the PCOS group compared with control group [45 (27-60) ms vs. 30 (26-38) ms, p<0.001]. Echocardiographic parameters of atrial EMI were significantly correlated with body mass index, Pd, and isovolumetric relaxation time in patients with PCOS. PCOS is associated with prolonged inter- and intra-atrial conduction times, which are related to increased AF risk.

Visual Working Memory Cannot Trade Quantity for Quality.

PubMed

Ramaty, Ayelet; Luria, Roy

2018-01-01

Two main models have been proposed to describe how visual working memory (WM) allocates its capacity: the slot-model and the continuous resource-model. The purpose of the current study was to test a direct prediction of the resource model suggesting that WM can trade-off between the quantity and quality of the encoded information. Previous research reported equivocal results, with studies that failed to find such a trade-off and other studies that reported a trade-off. Following the design of previous studies, in Experiment 1 we replicated this trade-off, by presenting the memory array for 1200 ms. Experiment 2 failed to observe a trade-off between quantity and quality using a memory array interval of 300 ms (a standard interval for visual WM). Experiment 3 again failed to find this trade-off, when reinstating the 1200 ms memory array interval but adding an articulatory suppression manipulation. We argue that while participants can trade quantity for quality, this pattern depends on verbal encoding and transfer to long-term memory processes that were possible to perform only during the long retention interval. When these processes were eliminated, the trade-off disappeared. Thus, we didn't find any evidence that the trade-off between quantity for quality can occur within visual WM.

Effect of maternal use of chewing gums containing xylitol on transmission of mutans streptococci in children: a meta-analysis of randomized controlled trials.

PubMed

Lin, Hsi-Kuei; Fang, Chia-En; Huang, Mao-Suan; Cheng, Hsin-Chung; Huang, Tsai-Wei; Chang, Hui-Ting; Tam, Ka-Wai

2016-01-01

Mutans streptococci (MS) are the major causative bacteria involved in human dental decay. Habitual consumption of xylitol has been proved to reduce MS levels in saliva and plaque. To evaluate the effect of the maternal use of xylitol gum on MS reduction in infants. A structured literature review and meta-analysis. A random effects model was used to assess the relative risks of the incidence of MS in the saliva or plaque of children who were 6, 9, 12, 18, and 24 months old. We reviewed 11 RCTs derived from 5 research teams that included 601 mothers. Our results indicated that the incidence of MS in the saliva or plaque of the infants was significantly reduced in the xylitol group (risk ratio: 0.54; 95% confidence interval: 0.39-0.73, at 12-18 months) and (risk ratio: 0.56; 95% confidence interval: 0.40-0.79, at 36 months) compared with the control groups. The long-term effect of maternal xylitol gum exposure on their children's dental caries was controversial. Habitual xylitol consumption by mothers with high MS levels was associated with a significant reduction in the mother-child transmission of salivary MS. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Maternal Oral Bacterial Levels Predict Early Childhood Caries Development

PubMed Central

Chaffee, B.W.; Gansky, S.A.; Weintraub, J.A.; Featherstone, J.D.B.; Ramos-Gomez, F.J.

2014-01-01

Objective: To calculate the association of maternal salivary bacterial challenge (mutans streptococci [MS] and lactobacilli [LB]) from pregnancy through 24 months’ postpartum with child caries incidence (≥1 cavitated or restored teeth) at 36 months. Materials & Methods: Dental, salivary bacterial, sociodemographic, and behavioral measures were collected at three- to six-month intervals from a birth cohort of low-income Hispanic mother-child dyads (N = 243). We calculated the relative child caries incidence, adjusted for confounding, following higher maternal challenge of MS (>4500 colony-forming units per milliliter of saliva [CFU/mL]) and LB (>50 CFU/mL) based on multivariable models. Results: Salivary MS and LB levels were greater among mothers of caries-affected children versus caries-free children. Mothers with higher salivary MS challenge were more likely to have MS-positive children (>0 CFU/mL), but maternal LB challenge was not a statistically significant predictor of child LB-positive status. Adjusting for sociodemographics, feeding and care practices, and maternal dental status, higher maternal salivary challenge of both MS and LB over the study period predicted nearly double the child caries incidence versus lower MS and LB (cumulative incidence ratio: 1.9; 95% confidence interval: 1.1, 3.8). Conclusion: Maternal salivary bacterial challenge not only is associated with oral infection among children but also predicts increased early childhood caries occurrence. PMID:24356441

Assessment of atrial electromechanical delay and P-wave dispersion in patients with psoriasis.

PubMed

Yildiz, Abdulkadir; Ucmak, Derya; Oylumlu, Mustafa; Akkurt, Meltem Z; Yuksel, Murat; Akil, Mehmet Ata; Acet, Halit; Polat, Nihat; Aydin, Mesut; Bilik, M Zihni

2014-10-01

In this study, we sought to evaluate atrial electromechanical properties and conduction homogeneity by tissue Doppler imaging and electrocardiography in patients with psoriasis. Thirty-four patients with psoriasis and 30 age- and gender-matched healthy controls were included in the study. Atrial electromechanical coupling intervals were assessed by means of tissue Doppler echocardiography and P-wave dispersion (Pd) was calculated from electrocardiogram. A total of 64 subjects (33 male) with a mean age of 36.8 ± 11.9 years were included in the study. Basal characteristics were similar between 2 groups. Intra-atrial (15 ± 7 ms vs. 12 ± 5 ms, P = 0.009) and inter-atrial (28 ± 7 ms vs. 23 ± 7 ms, P = 0.002) electromechanical delays were significantly higher in patients with psoriasis compared with control groups. P-maximum (112 ± 16 ms vs. 103 ± 8 ms, P = 0.006) and Pd (35 ± 9 ms vs. 20 ± 6 ms, P < 0.001) were also prolonged in patients with psoriasis. This study demonstrated that atrial electromechanical coupling intervals and P-wave dispersion were prolonged in patients with psoriasis, which may cause an increased risk of atrial fibrillation in this patient group. © 2014, Wiley Periodicals, Inc.

Electrocardiogram: his bundle potentials can be recorded noninvasively beat by beat on surface electrocardiogram.

PubMed

Wang, Gaopin; Liu, Renguang; Chang, Qinghua; Xu, Zhaolong; Zhang, Yingjie; Pan, Dianzhu

2017-03-15

The micro waveform of His bundle potential can't be recorded beat-to-beat on surface electrocardiogram yet. We have found that the micro-wavelets before QRS complex may be related to atrioventricular conduction system potentials. This study is to explore the possibility of His bundle potential can be noninvasively recorded on surface electrocardiogram. We randomized 65 patients undergoing radiofrequency catheter ablation of paroxysmal superventricular tachycardia (exclude overt Wolff-Parkinson-White syndrome) to receive "conventional electrocardiogram" and "new electrocardiogram" before the procedure. His bundle electrogram was collected during the procedure. Comparative analysis of PA s (PA interval recorded on surface electrocardiogram), AH s (AH interval recorded on surface electrocardiogram) and HV s (HV interval recorded on surface electrocardiogram) interval recorded on surface "new electrocardiogram" and PA, AH, HV interval recorded on His bundle electrogram was investigated. There was no difference (P > 0.05) between groups in HV s interval (49.63 ± 6.19 ms) and HV interval (49.35 ± 6.49 ms). Results of correlational analysis found that HV S interval was significantly positively associated with HV interval (r = 0.929; P < 0.01). His bundle potentials can be noninvasively recorded on surface electrocardiogram. Noninvasive His bundle potential tracing might represent a new method for locating the site of atrioventricular block and identifying the origin of a wide QRS complex.

Levofloxacin can be used effectively as a positive control in thorough QT/QTc studies in healthy volunteers

PubMed Central

Taubel, Jorg; Naseem, Asif; Harada, Tomohiko; Wang, Duolao; Arezina, Radivoj; Lorch, Ulrike; Camm, A John

2010-01-01

AIMS To characterize the effects of levofloxacin on QT interval in healthy subjects and the most appropriate oral positive control treatments for International Conference on Harmonization (ICH) E14 QT/QTc studies. METHODS Healthy subjects received a single dose of levofloxacin (1000 or 1500 mg), moxifloxacin (400 mg) or placebo in a four-period crossover design. Digital 12-lead ECGs were recorded in triplicate. Measurement of QT interval was performed automatically with subsequent manual onscreen over-reading using electronic callipers. Blood samples were taken for determination of levofloxacin and moxifloxacin concentrations. RESULTS Mean QTcI (QT interval corrected for heart rate using a correction factor that is applicable to each individual) was prolonged in subjects receiving moxifloxacin 400 mg compared with placebo. The largest time-matched difference in QTcI for moxifloxacin compared with placebo was observed to be 13.19 ms (95% confidence interval 11.21, 15.17) at 3.5 h post dose. Prolonged mean QTcI was also observed in subjects receiving levofloxacin 1000 mg and 1500 mg compared with placebo. The largest time-matched difference in QTcI compared with placebo was observed at 3.5 h post dose for both 1000 mg and 1500 mg of levofloxacin [mean (95%) 4.42 ms (2.44, 6.39) in 1000 mg and 7.44 ms (5.47, 9.42) in 1500 mg]. A small increase in heart rate was observed with levofloxacin during the course of the study. However, moxifloxacin showed a greater increase compared with levofloxacin. CONCLUSIONS Both levofloxacin and moxifloxacin can fulfil the criteria for a positive comparator. The ICH E14 guidelines recommend a threshold of around 5 ms for a positive QT/QTc study. The largest time-matched difference in QTc for levofloxacin suggests the potential for use in more rigorous QT/QTc studies. This study has demonstrated the utility of levofloxacin on the assay in measuring mean QTc changes around 5 ms. PMID:20406223

Controlling the carrier-envelope phase of Raman-generated periodic waveforms.

PubMed

Hsieh, Zhi-Ming; Lai, Chien-Jen; Chan, Han-Sung; Wu, Sih-Ying; Lee, Chao-Kuei; Chen, Wei-Jan; Pan, Ci-Ling; Yee, Fu-Goul; Kung, A H

2009-05-29

We demonstrate control of the carrier-envelope phase of ultrashort periodic waveforms that are synthesized from a Raman-generated optical frequency comb. We generated the comb by adiabatically driving a molecular vibrational coherence with a beam at a fundamental frequency plus its second harmonic. Heterodyne measurements show that full interpulse phase locking of the comb components is realized. The results set the stage for the synthesis of periodic arbitrary waveforms in the femtosecond and subfemtosecond regimes with full control.

The fine temporal structure of the rat licking pattern: what causes the variabiliy in the interlick intervals and how is it affected by the drinking solution?

PubMed

Lin, Xiong Bin; Pierce, Dwight R; Light, Kim Edward; Hayar, Abdallah

2013-10-01

Licking is a repetitive behavior controlled by a central pattern generator. Even though interlick intervals (ILIs) within bursts of licks are considered fairly regular, the conditions that affect their variability are unknown. We analyzed the licking pattern in rats that licked water, 10% sucrose solution, or 10% ethanol solution, in 90-min recording sessions after 4h of water deprivation. The histograms of ILIs indicate that licking typically occurred at a preferred ILI of about 130-140ms with evidence of bimodal or multimodal distributions due to occasional licking failures. We found that the longer the pause between bursts of licks, the shorter was the first ILI of the burst. When bursts of licks were preceded by a pause >4 s, the ILI was the shortest (~110ms) at the beginning of the burst, and then it increased rapidly in the first few licks and slowly in subsequent licks. Interestingly, the first ILI of a burst of licks was not significantly different when licking any of the 3 solutions, but subsequent licks exhibited a temporal pattern characteristic of each solution. The rapid deceleration in intraburst licking rate was due to an increase from ~27ms to ~56ms in the tongue-spout contact duration while the intercontact interval was only slightly changed (80-90ms). Therefore, the contact duration seems to be the major factor that increases the variability in the ILIs and could be another means for the rat to adjust the amount of fluid ingested in each individual lick.

Estimated preejection period (PEP) based on the detection of the R-wave and dZ/dt-min peaks in ECG and ICG

NASA Astrophysics Data System (ADS)

van Lien, René; Schutte, Nienke M.; Meijer, Jan H.; de Geus, Eco J. C.

2013-04-01

The validity of estimating the PEP from a fixed value for the Q-wave onset to the R-wave peak (QR) interval and from the R-wave peak to the dZ/dt-min peak (ISTI) interval is evaluated. Ninety-one subjects participated in a laboratory experiment in which a variety of physical and mental stressors were presented and 31 further subjects participated in a sequence of structured ambulatory activities in which large variation in posture and physical activity was induced. PEP, QR interval, and ISTI were scored. Across the diverse laboratory and ambulatory conditions the QR interval could be approximated by a fixed interval of 40 ms but 95% confidence intervals were large (25 to 54 ms). Multilevel analysis showed that 79% to 81% of the within and between-subject variation in the RB interval could be predicted by the ISTI. However, the optimal intercept and slope values varied significantly across subjects and study setting. Bland-Altman plots revealed a large discrepancy between the estimated PEP and the actual PEP based on the Q-wave onset and B-point. It is concluded that the estimated PEP can be a useful tool but cannot replace the actual PEP to index cardiac sympathetic control.

Translating QT interval prolongation from conscious dogs to humans.

PubMed

Dubois, Vincent F S; Smania, Giovanni; Yu, Huixin; Graf, Ramona; Chain, Anne S Y; Danhof, Meindert; Della Pasqua, Oscar

2017-02-01

In spite of screening procedures in early drug development, uncertainty remains about the propensity of new chemical entities (NCEs) to prolong the QT/QTc interval. The evaluation of proarrhythmic activity using a comprehensive in vitro proarrhythmia assay does not fully account for pharmacokinetic-pharmacodynamic (PKPD) differences in vivo. In the present study, we evaluated the correlation between drug-specific parameters describing QT interval prolongation in dogs and in humans. Using estimates of the drug-specific parameter, data on the slopes of the PKPD relationships of nine compounds with varying QT-prolonging effects (cisapride, sotalol, moxifloxacin, carabersat, GSK945237, SB237376 and GSK618334, and two anonymized NCEs) were analysed. Mean slope estimates varied between -0.98 ms μM -1 and 6.1 ms μM -1 in dogs and -10 ms μM -1 and 90 ms μM -1 in humans, indicating a wide range of effects on the QT interval. Linear regression techniques were then applied to characterize the correlation between the parameter estimates across species. For compounds without a mixed ion channel block, a correlation was observed between the drug-specific parameter in dogs and humans (y = -1.709 + 11.6x; R 2  = 0.989). These results show that per unit concentration, the drug effect on the QT interval in humans is 11.6-fold larger than in dogs. Together with information about the expected therapeutic exposure, the evidence of a correlation between the compound-specific parameter in dogs and in humans represents an opportunity for translating preclinical safety data before progression into the clinic. Whereas further investigation is required to establish the generalizability of our findings, this approach can be used with clinical trial simulations to predict the probability of QT prolongation in humans. © 2016 The British Pharmacological Society.

Prognostic significance of fever-induced Brugada syndrome.

PubMed

Mizusawa, Yuka; Morita, Hiroshi; Adler, Arnon; Havakuk, Ofer; Thollet, Aurélie; Maury, Philippe; Wang, Dao W; Hong, Kui; Gandjbakhch, Estelle; Sacher, Frédéric; Hu, Dan; Amin, Ahmad S; Lahrouchi, Najim; Tan, Hanno L; Antzelevitch, Charles; Probst, Vincent; Viskin, Sami; Wilde, Arthur A M

2016-07-01

In Brugada syndrome (BrS), spontaneous type 1 electrocardiogram (ECG) is an established risk marker for fatal arrhythmias whereas drug-induced type 1 ECG shows a relatively benign prognosis. No study has analyzed the prognosis of fever-induced type 1 ECG (F-type1) in a large BrS cohort. The objectives of this study were to assess the prognosis of F-type1 in asymptomatic BrS and to compare the effects of fever and drugs on ECG parameters. One hundred twelve patients with BrS who developed F-type1 were retrospectively enrolled. Prognosis was evaluated in 88 asymptomatic patients. In a subgroup (n = 52), ECG parameters of multiple ECGs (at baseline, during fever, and after drug challenge) were analyzed. Eighty-eight asymptomatic patients had a mean age of 45.8 ± 18.7 years, and 71.6% (67 of 88) were men. Twenty-one percent (18 of 88) had a family history of sudden cardiac death, and 26.4% (14 of 53) carried a pathogenic SCN5A mutation. Drug challenge was positive in 29 of 36 patients tested (80.6%). The risk of ventricular fibrillation in asymptomatic patients was 0.9%/y (3 of 88; 43.6 ± 37.4 months). ST-segment elevation in lead V2 during fever and after drug challenge was not significantly different (0.41 ± 0.21 ms during fever and 0.40 ± 0.30 ms after drug challenge; P > .05). Fever shortened the PR interval compared to baseline, whereas drug challenge resulted in prolonged PR interval and QRS duration (PR interval: 169 ± 29 ms at baseline, 148 ± 45 ms during fever, and 202 ± 35 ms after drug challenge; QRS duration: 97 ± 18 ms at baseline, 92 ± 28 ms during fever, and 117 ± 21 ms after drug challenge). Patients with BrS who develop F-type1 are at risk of arrhythmic events. F-type1 appears to develop through a more complex mechanism as compared with drug-induced type 1 ECG. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Temporal dynamics underlying the modulation of social status on social attention.

PubMed

Dalmaso, Mario; Galfano, Giovanni; Coricelli, Carol; Castelli, Luigi

2014-01-01

Fixating someone suddenly moving the eyes is known to trigger a corresponding shift of attention in the observer. This phenomenon, known as gaze-cueing effect, can be modulated as a function of the social status of the individual depicted in the cueing face. Here, in two experiments, we investigated the temporal dynamics underlying this modulation. To this end, a gaze-cueing paradigm was implemented in which centrally-placed faces depicting high- and low-status individuals suddenly shifted the eyes towards a location either spatially congruent or incongruent with that occupied by a subsequent target stimulus. Social status was manipulated by presenting fictive Curriculum Vitae before the experimental phase. In Experiment 1, in which two temporal intervals (50 ms vs. 900 ms) occurred between the direct-gaze face and the averted-gaze face onsets, a stronger gaze-cueing effect in response to high-status faces than low-status faces was observed, irrespective of the time participants were allowed for extracting social information. In Experiment 2, in which two temporal intervals (200 ms vs. 1000 ms) occurred between the averted-gaze face and target onset, a stronger gaze cueing for high-status faces was observed at the shorter interval only. Taken together, these results suggest that information regarding social status is extracted from faces rapidly (Experiment 1), and that the tendency to selectively attend to the locations gazed by high-status individuals may decay with time (Experiment 2).

A novel device based on smart textile to control heart's activity during exercise.

PubMed

Romagnoli, Marco; Alis, Rafael; Guillen, Javier; Basterra, Javier; Villacastin, J P; Guillen, Sergio

2014-06-01

In recent years, several systems have been developed to control cardiac function during exercise, and some are also capable of recording RR data to provide heart rate variability (HRV) analyses. In this study we compare time between heart beats and HRV parameters obtained with a smart textile system (GOW; Weartech sl., Spain) and an electrocardiogram machine commonly used in hospitals during continuous cycling tests. Twelve cardiology patients performed a 30-min cycling test at stable submaximal intensity. RR interval data were recorded during the test by both systems. 3-min RR segments were taken to compare the time intervals between beats and HRV variables using Bland-Altman analyses and intraclass correlation coefficients. Limits of agreement (LoAs) on RR intervals were stable at around 3 ms (widest LoAs -5.754 to 6.094 ms, tightest LoAs -2.557 to 3.105 ms, medium LoAs -3.638 ± 0.812 to 3.145 ± 0.539 ms). HRV parameters related to short-term change presented wide LoAs (RMSSD -0.17 to 18.41 %, HF -17.64 to 33.21 %, SD1 -0.50 to 17.54 %) as an effect of the error measurement of the GOW system. The GOW system is a valid tool for controlling HR during physical activity, although its use as a clinical tool for HRV cannot be supported.

The Presence or Absence of QTc Prolongation in Buprenorphine-Naloxone Among Youth with Opioid Dependence

PubMed Central

Poole, Sabrina A.; Pecoraro, Anna; Subramaniam, Geetha; Woody, George; Vetter, Victoria L

2015-01-01

Objective To evaluate buprenorphine-naloxone effects on the QTc in youth with opioid dependence. Buprenorphine is a partial agonist that is an effective treatment for opioid dependence. Compared to methadone it has a lower risk of QTc prolongation in adults but is less well studied in youth. It may also reduce the risk for torsades de pointes (TdP) an uncommon variant of polymorphic ventricular tachycardia, that can result in syncope, ventricular fibrillation, and sudden death. Methods Secondary analysis of ECG data from 95 subjects who participated in a multi-site trial for youth with opioid dependence. Subjects were randomized to a 2-week (DETOX), or a 12-week course of buprenorphine-naloxone (BUP). 12-lead ECGs were done at baseline, weeks 4 and 12, and QTc intervals were hand measured and calculated using Bazett's formula. Increases > 60 milliseconds (ms) were considered clinically significant, and readings > 450 ms (males) and 470 ms (females) indicated a prolonged QTc. Results Mean QTc intervals were higher for BUP than DETOX participants at baseline, week 4, and week 12 (p = 0.045), and females had longer mean QTc intervals than males (p < 0.0005). Variations in QTc intervals were observed in some, however none were above 500 ms, the level at which risk for TdP becomes more significant. Conclusion In this randomized trial, the mean QTc at baseline, before randomization, was higher in BUP than DETOX patients. Minimal changes in the QTc were seen at 4 and 12-weeks in a few patients in both groups. There was no evidence that buprenorphine-naloxone alone increased the QTc to a level that increased the risk for TdP. PMID:26690291

Effects of anthracycline, cyclophosphamide and taxane chemotherapy on QTc measurements in patients with breast cancer.

PubMed

Veronese, Pedro; Hachul, Denise Tessariol; Scanavacca, Mauricio Ibrahim; Hajjar, Ludhmila Abrahão; Wu, Tan Chen; Sacilotto, Luciana; Veronese, Carolina; Darrieux, Francisco Carlos da Costa

2018-01-01

Acute and subacute cardiotoxicity are characterized by prolongation of the corrected QT interval (QTc) and other measures derived from the QTc interval, such as QTc dispersion (QTdc) and transmural dispersion of repolarization (DTpTe). Although anthracyclines prolong the QTc interval, it is unclear whether breast cancer patients who undergo the ACT chemotherapy regimen of anthracycline (doxorubicin: A), cyclophosphamide (C) and taxane (T) may present with QTc, QTdc and DTpTe prolongation. Twenty-three consecutive patients with breast cancer were followed prospectively during ACT chemotherapy and were analyzed according to their QT measurements. QTc, QTdc and DTpTe measurements were determined by a 12-lead electrocardiogram (EKG) prior to chemotherapy (baseline), immediately after the first phase of anthracycline and cyclophosphamide (AC) treatment, and immediately after T treatment. Serum troponin and B-type natriuretic peptide (BNP) levels were also measured. Compared to baseline values, the QTc interval was significantly prolonged after the AC phase (439.7 ± 33.2 ms vs. 472.5 ± 36.3 ms, p = 0.001) and after T treatment (439.7 ± 33.2 ms vs. 467.9 ± 42.6 ms, p < 0.001). Troponin levels were elevated after the AC phase (23.0 pg/mL [min-max: 6.0-85.0] vs. 6.0 pg/mL [min-max: 6.0-22.0], p < 0.001) and after T treatment (25.0 pg/mL [min-max: 6.0-80.0] vs. 6.0 pg/mL [min-max: 6.0-22.0], p < 0.001) compared to baseline values. In this prospective study of patients with non-metastatic breast cancer who underwent ACT chemotherapy, significant QTc prolongation and an elevation in serum troponin levels were observed.

Automatic attentional orienting to other people's gaze in schizophrenia.

PubMed

Langdon, Robyn; Seymour, Kiley; Williams, Tracey; Ward, Philip B

2017-08-01

Explicit tests of social cognition have revealed pervasive deficits in schizophrenia. Less is known of automatic social cognition in schizophrenia. We used a spatial orienting task to investigate automatic shifts of attention cued by another person's eye gaze in 29 patients and 28 controls. Central photographic images of a face with eyes shifted left or right, or looking straight ahead, preceded targets that appeared left or right of the cue. To examine automatic effects, cue direction was non-predictive of target location. Cue-target intervals were 100, 300, and 800 ms. In non-social control trials, arrows replaced eye-gaze cues. Both groups showed automatic attentional orienting indexed by faster reaction times (RTs) when arrows were congruent with target location across all cue-target intervals. Similar congruency effects were seen for eye-shift cues at 300 and 800 ms intervals, but patients showed significantly larger congruency effects at 800 ms, which were driven by delayed responses to incongruent target locations. At short 100-ms cue-target intervals, neither group showed faster RTs for congruent than for incongruent eye-shift cues, but patients were significantly slower to detect targets after direct-gaze cues. These findings conflict with previous studies using schematic line drawings of eye-shifts that have found automatic attentional orienting to be reduced in schizophrenia. Instead, our data indicate that patients display abnormalities in responding to gaze direction at various stages of gaze processing-reflected by a stronger preferential capture of attention by another person's direct eye contact at initial stages of gaze processing and difficulties disengaging from a gazed-at location once shared attention is established.

Differential Changes in Myocardial Performance Index and Its Time Intervals in Donors and Recipients of Twin-to-Twin Transfusion Syndrome before and after Laser Therapy.

PubMed

Ortiz, Javier U; Torres, Ximena; Eixarch, Elisenda; Bennasar, Mar; Cruz-Lemini, Monica; Gómez, Olga; Lobmaier, Silvia M; Martínez, Josep M; Gratacós, Eduard; Crispi, Fatima

2018-01-19

To evaluate left myocardial performance index (MPI) and time intervals in fetuses with twin-to-twin transfusion syndrome (TTTS) before and after laser surgery. Fifty-one fetal pairs with TTTS and 47 uncomplicated monochorionic twin pairs were included. Left ventricular isovolumetric contraction time (ICT), ejection time (ET), and isovolumetric relaxation time (IRT) were measured using conventional Doppler. Recipients showed prolonged ICT (46 ± 12 vs. 31 ± 8 vs. 30 ± 5 ms; p < 0.001) and IRT (51 ± 9 vs. 43 ± 8 vs. 43 ± 5 ms; p < 0.001) and higher MPI (0.57 ± 0.12 vs. 0.47 ± 0.09 vs. 0.44 ± 0.05; p < 0.001) than donors and controls. Donors showed shorter ET than recipients and controls (157 ± 12 vs. 169 ± 10 vs. 168 ± 10 ms; p < 0.001) and higher MPI than controls (0.47 ± 0.09 vs. 0.44 ± 0.05; p = 0.006). Preoperative MPI changes were observed in all TTTS stages. Time intervals partially improved after surgery. Donor and recipient twins had higher MPI due to different changes in the time intervals, possibly reflecting the state of hypovolemia in the donor and hypervolemia and pressure overload in the recipient. © 2018 S. Karger AG, Basel.

Within-Subject Testing of the Signaled-Reinforcement Effect on Operant Responding as Measured by Response Rate and Resistance to Change

ERIC Educational Resources Information Center

Reed, Phil; Doughty, Adam H.

2005-01-01

Response rates under random-interval schedules are lower when a brief (500 ms) signal accompanies reinforcement than when there is no signal. The present study examined this signaled-reinforcement effect and its relation to resistance to change. In Experiment 1, rats responded on a multiple random-interval 60-s random-interval 60-s schedule, with…

Tricaine (MS-222) is a safe anesthetic compound compared to benzocaine and pentobarbital to induce anesthesia in leopard frogs (Rana pipiens).

PubMed

Cakir, Yavuz; Strauch, Stephen M

2005-01-01

Tricaine (MS-222) is used commonly for sedation, immobilization, and anesthesia of poikilothermic animals. The anesthetic efficacy of different concentrations of MS-222 was compared to benzocaine and pentobarbital on the physiological changes, heart rate and ECG (electrocardiogram) parameters in the leopard frog, Rana pipiens. Loss of righting reflex (RR), loss of pain response (NR = nociceptor response) and recovery time were measured. Heart rate and ECG parameters were also tested before and during anesthesia. The time to loss of RR and NR decreased while recovery time markedly increased with the increasing concentration of MS-222. Benzocaine at 200 mg/l induced a rapid anesthesia, but all frogs needed resuscitation. Pentobarbital at 300 mg/l induced a slow anesthesia, however, all of the frogs also needed resuscitation. All anesthetics at the mentioned concentrations decreased heart rate significantly as well as altered the ECG parameters. All anesthetics prolonged the Q-T interval, and MS-222 at 800 mg/l and benzocaine at 200 mg/l were the most effective anesthetic concentrations in increasing the Q-T interval. Frogs anesthetized by benzocaine and pentobarbital and high concentrations of MS-222 required resuscitation due to hypoxia. Pentobarbital and benzocaine seem to be very effective compounds, but their safety margins are narrow because of ventilatory failure. Therefore, MS-222 at a concentration of 200 mg/l or less is highly recommended for leopard frogs because prolonged recovery, high mortality rate and significant ECG changes are observed with higher concentrations of MS-222.

Nocturnal heart rate variability is lower in temporomandibular disorder patients than in healthy, pain-free individuals.

PubMed

Eze-Nliam, Chete M; Quartana, Phillip J; Quain, Angela M; Smith, Michael T

2011-01-01

To determine whether patients with a painful myofascial temporomandibular disorder (TMD) have diminished nocturnal heart rate variability (HRV), a marker of autonomic nervous system (ANS) dysfunction, relative to healthy, pain-free controls. Participants with myofascial TMD and healthy, pain-free volunteers underwent nocturnal polysomnography studies during which HRV indices were measured. Multiple linear regression analyses were used to determine whether TMD status exerted unique effects on HRV. Ninety-five participants (n = 37 TMD; n = 58 controls) were included in the analyses. The TMD group had a lower standard deviation of R-R intervals (89.81 ± 23.54 ms versus 107.93 ± 34.42 ms, P ⋜ .01), a lower root mean squared successive difference (RMSSD) of R-R intervals (54.78 ± 27.37 ms versus 81.88 ± 46.43 ms, P < .01), and a lower high frequency spectral power (2336.89 ± 1224.64 ms² versus 2861.78 ± 1319 ms², P = .05) than the control group. The ratio of the low-frequency (LF) to the high-frequency (HF) spectral power was higher in the TMD group (2.47 ± 2 versus 1.38 ± 0.65, P < .01). The differences in RMSSD (91.21 ms versus 112.03 ms, P = .05) and LF:HF ratio (0.71 versus 0.32, P < .01) remained significant after controlling for age and psychological distress. Myofascial TMD patients revealed lower nocturnal HRV than healthy, pain-free controls. Further research should focus on processes that address this ANS imbalance, which may potentially lead to effective therapeutic interventions.

Molecular and Behavioral Differentiation among Brazilian Populations of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae)

PubMed Central

Araki, Alejandra S.; Vigoder, Felipe M.; Bauzer, Luiz G. S. R.; Ferreira, Gabriel E. M.; Souza, Nataly A.; Araújo, Izeneide B.; Hamilton, James G. C.; Brazil, Reginaldo P.; Peixoto, Alexandre A.

2009-01-01

Background Lutzomyia longipalpis is the primary vector of American visceral leishmaniasis. There is strong evidence that L. longipalpis is a species complex, but until recently the existence of sibling species among Brazilian populations was considered a controversial issue. In addition, there is still no consensus regarding the number of species occurring in this complex. Methodology/Principal Findings Using period, a gene that controls circadian rhythms and affects interpulse interval periodicity of the male courtship songs in Drosophila melanogaster and close relatives, we analyzed the molecular polymorphism in a number of L. longipalpis samples from different regions in Brazil and compared the results with our previously published data using the same marker. We also studied the male copulation songs and pheromones from some of these populations. The results obtained so far suggest the existence of two main groups of populations in Brazil, one group representing a single species with males producing Burst-type copulation songs and cembrene-1 pheromones; and a second group that is more heterogeneous and probably represents a number of incipient species producing different combinations of Pulse-type songs and pheromones. Conclusions/Significance Our results reveal a high level of complexity in the divergence and gene-flow among Brazilian populations of the L. longipalpis species complex. This raises important questions concerning the epidemiological consequences of this incipient speciation process. PMID:19172187

Pure-phase selective excitation in fast-relaxing systems.

PubMed

Zangger, K; Oberer, M; Sterk, H

2001-09-01

Selective pulses have been used frequently for small molecules. However, their application to proteins and other macromolecules has been limited. The long duration of shaped-selective pulses and the short T(2) relaxation times in proteins often prohibited the use of highly selective pulses especially on larger biomolecules. A very selective excitation can be obtained within a short time by using the selective excitation sequence presented in this paper. Instead of using a shaped low-intensity radiofrequency pulse, a cluster of hard 90 degrees pulses, delays of free precession, and pulsed field gradients can be used to selectively excite a narrow chemical shift range within a relatively short time. Thereby, off-resonance magnetization, which is allowed to evolve freely during the free precession intervals, is destroyed by the gradient pulses. Off-resonance excitation artifacts can be removed by random variation of the interpulse delays. This leads to an excitation profile with selectivity as well as phase and relaxation behavior superior to that of commonly used shaped-selective pulses. Since the evolution of scalar coupling is inherently suppressed during the double-selective excitation of two different scalar-coupled nuclei, the presented pulse cluster is especially suited for simultaneous highly selective excitation of N-H and C-H fragments. Experimental examples are demonstrated on hen egg white lysozyme (14 kD) and the bacterial antidote ParD (19 kD). Copyright 2001 Academic Press.

Evaluation of Tp-e interval and Tp-e/QT ratio in patients with non-dipper hypertension.

PubMed

Demir, Mehmet; Uyan, Umut

2014-01-01

Non-dipper hypertension is associated with increased cardiovascular morbidity and mortality. Several studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the transmural dispersion of repolarization and that increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. The aim of this study was to evaluate ventricular repolarization by using Tp-e interval and Tp-e/QT ratio in patients with non-dipper hypertension. This study included 80 hypertensive patients. Hypertensive patients were divided into two groups: 50 dipper patients (29 male, mean age 51.5 ± 8 years) and 30 non-dipper patients (17 male, mean age 50.6 ± 5.4 years). Tp-e interval and Tp-e/QT ratio were measured from the 12-lead electrocardiogram. These parameters were compared between groups. No statistically significant difference was found between two groups in terms of basic characteristics. In electrocardiographic parameters analysis, QT dispersion (QTd) and corrected QTd were significantly increased in non-dipper patients compared to the dippers (39.4 ± 11.5 versus 27.3 ± 7.5 ms and 37.5 ± 9.5 versus 29.2 ± 6.5 ms, p = 0.001 and p = 0.01, respectively). Tp-e interval and Tp-e/QT ratio were also significantly higher in non-dipper patients (97.5 ± 11.2 versus 84.2 ± 8.3 ms and 0.23 ± 0.02 versus 0.17 ± 0.02, all p value <0.001). Our study revealed that QTd, Tp-e interval and Tp-e/QT ratio are prolonged in patients with non-dipper hypertension.

OBSERVATIONS OF THE CRAB PULSAR BETWEEN 25 AND 100 GeV WITH THE MAGIC I TELESCOPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aleksic, J.; Blanch, O.; Alvarez, E. A.

2011-11-20

We report on the observation of {gamma}-rays above 25 GeV from the Crab pulsar (PSR B0532+21) using the MAGIC I telescope. Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used. In order to discuss the spectral shape from 100 MeV to 100 GeV, one year of public Fermi Large Area Telescope (Fermi-LAT) data are also analyzed to complement the MAGIC data. The extrapolation of the exponential cutoff spectrum determined with the Fermi-LAT data is inconsistent with MAGIC measurements, which requires a modification of the standard pulsar emission models. In the energy region between 25 andmore » 100 GeV, the emission in the P1 phase (from -0.06 to 0.04, location of the main pulse) and the P2 phase (from 0.32 to 0.43, location of the interpulse) can be described by power laws with spectral indices of -3.1 {+-} 1.0{sub stat} {+-} 0.3{sub syst} and -3.5 {+-} 0.5{sub stat} {+-} 0.3{sub syst}, respectively. Assuming an asymmetric Lorentzian for the pulse shape, the peak positions of the main pulse and the interpulse are estimated to be at phases -0.009 {+-} 0.007 and 0.393 {+-} 0.009, while the full widths at half-maximum are 0.025 {+-} 0.008 and 0.053 {+-} 0.015, respectively.« less

Control of periodic surface structures on silicon by combined temporal and polarization shaping of femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Fraggelakis, F.; Stratakis, E.; Loukakos, P. A.

2018-06-01

We demonstrate the capability to exercise advanced control on the laser-induced periodic surface structures (LIPSS) on silicon by combining the effect of temporal shaping, via tuning the interpulse temporal delay between double femtosecond laser pulses, along with the independent manipulation of the polarization state of each of the individual pulses. For this, cross-polarized (CP) as well as counter-rotating (CR) double circularly polarized pulses have been utilized. The pulse duration was 40 fs and the central wavelength of 790 nm. The linearly polarized double pulses are generated by a modified Michelson interferometer allowing the temporal delay between the pulses to vary from Δτ = -80 ps to Δτ = +80 ps with an accuracy of 0.2 fs. We show the significance of fluence balance between the two pulse components and its interplay with the interpulse delay and with the order of arrival of the individually polarized pulse components of the double pulse sequence on the final surface morphology. For the case of CR pulses we found that when the pulses are temporally well separated the surface morphology attains no axial symmetry. But strikingly, when the two CP pulses temporally overlap, we demonstrate, for the first time in our knowledge, the detrimental effect that the phase delay has on the ripple orientation. Our results provide new insight showing that temporal pulse shaping in combination with polarization control gives a powerful tool for drastically controlling the surface nanostructure morphology.

The time course of face processing: startle eyeblink response modulation by face gender and expression.

PubMed

Duval, Elizabeth R; Lovelace, Christopher T; Aarant, Justin; Filion, Diane L

2013-12-01

The purpose of this study was to investigate the effects of both facial expression and face gender on startle eyeblink response patterns at varying lead intervals (300, 800, and 3500ms) indicative of attentional and emotional processes. We aimed to determine whether responses to affective faces map onto the Defense Cascade Model (Lang et al., 1997) to better understand the stages of processing during affective face viewing. At 300ms, there was an interaction between face expression and face gender with female happy and neutral faces and male angry faces producing inhibited startle. At 3500ms, there was a trend for facilitated startle during angry compared to neutral faces. These findings suggest that affective expressions are perceived differently in male and female faces, especially at short lead intervals. Future studies investigating face processing should take both face gender and expression into account. © 2013.

Filtering Drifter Trajectories Sampled at Submesoscale Resolution

DTIC Science & Technology

2015-07-10

interval 5 min and a positioning error 1.5 m, the acceleration error is 4 10 m/s , a value comparable with the typical Coriolis acceleration of a water...10 ms , corresponding to the Coriolis acceleration experi- enced by a water parcel traveling at a speed of 2.2 m/s. This value corresponds to the...computed by integrating the NCOM velocity field contaminated by a random walk process whose effective dispersion coefficient (150 m /s) was specified as the

Lack of effect of perampanel on QT interval duration: Results from a thorough QT analysis and pooled partial seizure Phase III clinical trials.

PubMed

Yang, Haichen; Laurenza, Antonio; Williams, Betsy; Patten, Anna; Hussein, Ziad; Ferry, Jim

2015-08-01

Perampanel is a selective, noncompetitive AMPA receptor antagonist approved as adjunctive treatment for partial seizures. To assess potential for delayed cardiac repolarization, a Phase I thorough QT study was performed, supplemented by plasma concentration-QT data modeled from 3 pooled Phase III studies. The Phase I thorough QT study (double-blind, combined fixed-sequence, parallel-group) quantified the effect of perampanel (6 mg once daily for 7 days, followed by dose escalation to a single 8-mg dose, a single 10-mg dose, then 12 mg once daily for 7 days), moxifloxacin positive control (single 400-mg dose on Day 16), and placebo on QT interval duration in healthy subjects (N = 261). Electrocardiograms were recorded at baseline, Day 7 (post 6 mg dose), and Day 16 (post 12 mg dose). Statistical comparisons were between the highest approved perampanel dose (12 mg) versus placebo, a "mid-therapeutic" dose (6 mg) versus placebo, and moxifloxacin versus placebo. Acknowledging that the Phase I thorough QT study could not incorporate a true "supratherapeutic" dose due to length of titration and tolerability concerns in healthy subjects, Phase III studies of perampanel included expanded electrocardiogram safety evaluations specifically intended to support concentration-QT response modeling. The lack of effect of perampanel on the QT interval is shown from pooled analysis of 3 double-blind, placebo-controlled, 19-week, Phase III studies with perampanel doses ≤ 12 mg (N = 1038, total perampanel; and N=442, placebo) in patients with partial seizures. QT measures were corrected for heart rate using Fridericia's (QTcF; the primary endpoint) and Bazett's (QTcB) formulas. In the Phase I thorough QT study, the positive control moxifloxacin caused peak time-matched, baseline-adjusted, placebo-corrected (ΔΔ) QTcF of 12.15 ms at 4h postdose, confirming a drug effect on QTc interval and study assessment sensitivity. Mean baseline-adjusted (Δ) QTcF versus nominal time curves were comparable between perampanel 12 mg and placebo, with most ΔQTcF values being slightly negative. Healthy subjects receiving perampanel 6 and 12 mg doses for 7 days showed no evidence of effects on cardiac repolarization. Peak ΔΔQTcF was 2.34 ms at 1.5h postdose for perampanel 6 mg and 3.92 ms at 0.5h postdose for perampanel 12 mg. At every time point, the upper 95% confidence limit of ΔΔQTcF for perampanel 6 and 12 mg was <10 ms. Phase III studies revealed no clinically significant difference between patients with partial seizures treated with perampanel or placebo in QTcF and QTcB values >450 ms, with no dose-dependent increases or large incremental changes from baseline of >60 ms. Regression analysis of individual plasma perampanel concentrations versus corresponding QTc interval values in Phase I thorough QT and Phase III studies demonstrated no relationship between perampanel concentrations and QT interval duration. Treatment with perampanel 6 mg and 12 mg for 7 days did not delay cardiac repolarization in healthy volunteers. In a population analysis of 1480 patients with partial seizures treated with perampanel doses ≤ 12 mg or placebo, no clinically significant trends in QT interval data were noted. Based on the thorough QT study and evaluations from pooled Phase III studies, there is no evidence of prolonged QT interval duration with perampanel treatment. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Effects of interstimulus intervals on behavioral, heart rate, and event-related potential indices of infant engagement and sustained attention

PubMed Central

Xie, Wanze; Richards, John E.

2016-01-01

Maximizing infant attention to stimulus presentation during an EEG or ERP experiment is important for making valid inferences about the neural correlates of infant cognition. The present study examined the effects of stimulus presentation interstimulus interval (ISI) on behavioral and physiological indices of infant attention including infants’ fixation to visual presentation, the amount of heart rate (HR) change during sustained attention, and ERP components. This study compared an ISI that is typically used in infant EEG/ERP studies (e.g., 1,500–2,000 ms) with two shorter durations (400–600 ms and 600–1,000 ms). Thirty-six infants were tested cross-sectionally at 3, 4.5, and 6 months. It was found that using the short (400–600 ms) and medium (600–1,000 ms) ISIs resulted in more visually fixated trials and reduced frequency of fixation disengagement per experimental block. We also found larger HR changes during sustained attention to both of the shorter ISIs compared with the long ISI, and larger ERP responses when using the medium ISI compared to using the short and long ISIs. These data suggest that utilizing an optimal ISI (e.g., 600– 1,000 ms), which increases the presentation complexity and provides sufficient time for information processing, can promote infant engagement and sustained attention during stimulus presentation. PMID:27159263

Determination of eight pesticides in Lycium barbarum by LC-MS/MS and dietary risk assessment.

PubMed

Fu, Yan; Yang, Ting; Zhao, Jian; Zhang, Liang; Chen, Ruoxia; Wu, Yinliang

2017-03-01

A LC-MS/MS method for determination of eight pesticides (triadimefon, sulfoxaflor, flusilazole, tebuconazole, difenoconazole, amitraz, azoxystrobin, and thiophanate-methyl) in Lycium barbarum was established. The samples were extracted with acetonitrile, and then cleaned up by primary secondary amine. The extracts were diluted with 0.1% formic acid in water. The results showed that at the fortified levels of 0.01-10mg/kg, the average recoveries of these pesticides ranged from 82.1% to 96.2% with the relative standard deviations lower than 7%. The half-lives of eight pesticides were 1.3-5.0days in Lycium barbarum fruits. The pre-harvest interval of all pesticides mentioned above were investigated. Tebuconazole (14days), sulfoxaflor (14days) and flusilazole (28days) have longer pre-harvest interval than the others which have 7days. The dietary risks, assessed as hazard quotients, were far below 100%. The results showed that the eight pesticides applied to Lycium barbarum were comparably safe for the consumer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Age effects on discrimination of timing in auditory sequences

NASA Astrophysics Data System (ADS)

Fitzgibbons, Peter J.; Gordon-Salant, Sandra

2004-08-01

The experiments examined age-related changes in temporal sensitivity to increments in the interonset intervals (IOI) of components in tonal sequences. Discrimination was examined using reference sequences consisting of five 50-ms tones separated by silent intervals; tone frequencies were either fixed at 4 kHz or varied within a 2-4-kHz range to produce spectrally complex patterns. The tonal IOIs within the reference sequences were either equal (200 or 600 ms) or varied individually with an average value of 200 or 600 ms to produce temporally complex patterns. The difference limen (DL) for increments of IOI was measured. Comparison sequences featured either equal increments in all tonal IOIs or increments in a single target IOI, with the sequential location of the target changing randomly across trials. Four groups of younger and older adults with and without sensorineural hearing loss participated. Results indicated that DLs for uniform changes of sequence rate were smaller than DLs for single target intervals, with the largest DLs observed for single targets embedded within temporally complex sequences. Older listeners performed more poorly than younger listeners in all conditions, but the largest age-related differences were observed for temporally complex stimulus conditions. No systematic effects of hearing loss were observed.

Transcranial electric stimulation for intraoperative motor evoked potential monitoring: dependence of required stimulation current on interstimulus interval value.

PubMed

Joksimovic, Boban; Szelenyi, Andrea; Seifert, Volker; Damjanovic, Aleksandar; Damjanovic, Aleksandra; Rasulic, Lukas

2015-05-01

To evaluate the relationship between stimulus intensity by constant current transcranial electric stimulation and interstimulus interval (ISI) for eliciting muscle motor evoked potentials (MEPs) in three different hand muscles and the tibialis anterior muscles. We tested intraoperatively different monophasic constant current pulses and ISIs in 22 patients with clinically normal motor function. Motor thresholds of contralateral muscle MEPs were determined at 0.5 milliseconds (ms) pulse duration and ISIs of 1, 2, 3, 4, 5, and 10 ms using a train of 2, 3, and 5 monophasic constant current pulses of 62 to 104 mA before craniotomy and after closure of the dura mater. The lowest stimulation threshold to elicit MEPs in the examined muscles was achieved with a train of 5 pulses (ISI: 3 ms) before craniotomy, which was statistically significant compared with 2 pulses (ISI: 3 ms) as well as 3 pulses (ISIs: 3 and 10 ms). An ISI of 3 ms gave the lowest motor thresholds with statistical significance compared with the ISIs of 4 ms (2 pulses) and of 1 ms (3 pulses). All current intensity (mA) and ISI (ms) relationship graphs had a trend of the exponential function as y = a + bx + c ρ (x), where y is intensity (mA) and x is ISI (ms). The minimum of the function was determined for each patient and each muscle. The difference was statistically significant between 3 and 5 pulses before craniotomy and between 3 and 5 pulses and 2 and 5 pulses after closure of the dura mater. In adult neurosurgical patients with a normal motor status, a train of 5 pulses and an ISI of 3 ms provide the lowest motor thresholds. We provided evidence of the dependence of required stimulation current on ISI. Georg Thieme Verlag KG Stuttgart · New York.

The effects of the preferential 5-HT2A agonist psilocybin on prepulse inhibition of startle in healthy human volunteers depend on interstimulus interval.

PubMed

Vollenweider, Franz X; Csomor, Philipp A; Knappe, Bernhard; Geyer, Mark A; Quednow, Boris B

2007-09-01

Schizophrenia patients exhibit impairments in prepulse inhibition (PPI) of the startle response. Hallucinogenic 5-HT(2A) receptor agonists are used for animal models of schizophrenia because they mimic some symptoms of schizophrenia in humans and induce PPI deficits in animals. Nevertheless, one report indicates that the 5-HT(2A) receptor agonist psilocybin increases PPI in healthy humans. Hence, we investigated these inconsistent results by assessing the dose-dependent effects of psilocybin on PPI in healthy humans. Sixteen subjects each received placebo or 115, 215, and 315 microg/kg of psilocybin at 4-week intervals in a randomized and counterbalanced order. PPI at 30-, 60-, 120-, 240-, and 2000-ms interstimulus intervals (ISIs) was measured 90 and 165 min after drug intake, coinciding with the peak and post-peak effects of psilocybin. The effects of psilocybin on psychopathological core dimensions and sustained attention were assessed by the Altered States of Consciousness Rating Scale (5D-ASC) and the Frankfurt Attention Inventory (FAIR). Psilocybin dose-dependently reduced PPI at short (30 ms), had no effect at medium (60 ms), and increased PPI at long (120-2000 ms) ISIs, without affecting startle reactivity or habituation. Psilocybin dose-dependently impaired sustained attention and increased all 5D-ASC scores with exception of Auditory Alterations. Moreover, psilocybin-induced impairments in sustained attention performance were positively correlated with reduced PPI at the 30 ms ISI and not with the concomitant increases in PPI observed at long ISIs. These results confirm the psilocybin-induced increase in PPI at long ISIs and reveal that psilocybin also produces a decrease in PPI at short ISIs that is correlated with impaired attention and consistent with deficient PPI in schizophrenia.

QTc prolongation after brain surgery.

PubMed

Capparelli, Federico J; Abello, Mauricio; Patricio Maskin, L; Arista, Eugenia; Hlavnicka, Alejandro; Diaz, Maria Fernanda; Varela, Daniel; Wainsztein, Nestor A

2013-03-01

Abnormalities observed in the electrocardiogram (ECG) after acute central nervous system (CNS) events have been reported. Our objective was to assess the incidence of heart rate-corrected QT interval (QTc) prolongation in patients admitted to the intensive care unit (ICU) after brain surgery. Admission standard 12-lead ECGs were analyzed blinded to patient data. The QT interval was measured and Bazzett's formula was used to obtain QTc. Prolonged QTc was defined as ≧450 ms. We included 114 patients in the study. The mean age was 49±17 years. Brain neoplasm was the surgical indication in 90% of the patients. The mean QTc was 470±42 ms. Prolonged QTc was found in 71% patients. The heart rate-corrected QT interval was between 450 ms and 500 ms in 52% and >500 ms in 19% of the patients. The heart rate and concentration of serum glucose were higher in the prolonged QTc group. Only 7·5% of all patients had hypokalemia (≤3 mEq/l). In the prolonged QTc group 9·2% had hypokalemia compared to 3·2% in normal QTc patients (P = 0·406). There were no significant associations between categories of QTc and the serum levels of creatinine, magnesium, calcium, sodium, or pH. Phenytoin and metoclopramide were not frequently used in patients with prolonged QTc. This study supports our hypothesis that prolonged QTc is frequently observed after a brain surgery. Hypokalemia, hypocalcaemia, and drugs such as metoclopramide or phenytoin could not explain the high incidence of prolonged QTc. Brain injury during a surgical procedure may be one of the primary causes of QTc prolongation after neurosurgery.

The Fine Temporal Structure of the Rat Licking Pattern: What Causes the Variabiliy in the Interlick Intervals and How is it Affected by the Drinking Solution?

PubMed Central

2013-01-01

Licking is a repetitive behavior controlled by a central pattern generator. Even though interlick intervals (ILIs) within bursts of licks are considered fairly regular, the conditions that affect their variability are unknown. We analyzed the licking pattern in rats that licked water, 10% sucrose solution, or 10% ethanol solution, in 90-min recording sessions after 4h of water deprivation. The histograms of ILIs indicate that licking typically occurred at a preferred ILI of about 130−140ms with evidence of bimodal or multimodal distributions due to occasional licking failures. We found that the longer the pause between bursts of licks, the shorter was the first ILI of the burst. When bursts of licks were preceded by a pause >4 s, the ILI was the shortest (~110ms) at the beginning of the burst, and then it increased rapidly in the first few licks and slowly in subsequent licks. Interestingly, the first ILI of a burst of licks was not significantly different when licking any of the 3 solutions, but subsequent licks exhibited a temporal pattern characteristic of each solution. The rapid deceleration in intraburst licking rate was due to an increase from ~27ms to ~56ms in the tongue-spout contact duration while the intercontact interval was only slightly changed (80−90ms). Therefore, the contact duration seems to be the major factor that increases the variability in the ILIs and could be another means for the rat to adjust the amount of fluid ingested in each individual lick. PMID:23902635

Effects of atomoxetine on the QT interval in healthy CYP2D6 poor metabolizers

PubMed Central

Loghin, Corina; Haber, Harry; Beasley, Charles M; Kothare, Prajakti A; Kauffman, Lynnette; April, John; Jin, Ling; Allen, Albert J; Mitchell, Malcolm I

2013-01-01

Aim The effects of atomoxetine (20 and 60 mg twice daily), 400 mg moxifloxacin and placebo on QTc in 131 healthy CYP2D6 poor metabolizer males were compared. Methods Atomoxetine doses were selected to result in plasma concentrations that approximated expected plasma concentrations at both the maximum recommended dose and at a supratherapeutic dose in CYP2D6 extensive metabolizers. Ten second electrocardiograms were obtained for time-matched baseline on days −2 and −1, three time points after dosing on day 1 for moxifloxacin and five time points on day 7 for atomoxetine and placebo. Maximum mean placebo-subtracted change from baseline model-corrected QT (QTcM) on day 7 was the primary endpoint. Results QTcM differences for atomoxetine 20 and 60 mg twice daily were 0.5 ms (upper bound of the one-sided 95% confidence interval 2.2 ms) and 4.2 ms (upper bound of the one-sided 95% confidence interval 6.0 ms), respectively. As plasma concentration of atomoxetine increased, a statistically significant increase in QTc was observed. The moxifloxacin difference from placebo met the a priori definition of non-inferiority. Maximum mean placebo-subtracted change from baseline QTcM for moxifloxacin was 4.8 ms and this difference was statistically significant. Moxifloxacin plasma concentrations were below the concentrations expected from the literature. However, the slope of the plasma concentration−QTc change observed was consistent with the literature. Conclusion Atomoxetine was not associated with a clinically significant change in QTc. However, a statistically significant increase in QTc was associated with increasing plasma concentrations. PMID:22803597

Cardiac repolarization during fingolimod treatment in patients with relapsing-remitting multiple sclerosis.

PubMed

Laiho, Aapo; Laitinen, Tiina M; Hartikainen, Päivi; Hartikainen, Juha E K; Laitinen, Tomi P; Simula, Sakari

2018-02-01

Fingolimod is a sphingosine-1-phosphate receptor modulator for the treatment of relapsing-remitting multiple sclerosis (RRMS). Despite an established effect on heart rate, the effect of fingolimod on cardiac repolarization is not completely known. Twenty-seven patients with RRMS underwent 24-hr ambulatory ECG before fingolimod (baseline), at the day of fingolimod initiation (1D) and after three-month treatment (3M). The mean values of RR-interval as well as QT-interval corrected by Bazzet's (QTcBaz) and Fridericia's (QTcFri) formula were compared between baseline, 1D, and 3M over 24-hr period as well as at daytime and nighttime. QTcBaz over 24-hr was shorter at 1D (414 ± 20 ms, p  < .001) and at 3M (414 ± 20 ms, p  < .001) than at baseline (418 ± 20 ms). In contrast, QTcFri over 24-hr was longer at 1D (410 ± 19 ms, p  < .001) but similar at 3M (406 ± 19 ms, p  = .355) compared to baseline (407 ± 19 ms). Daytime QTcBaz was shorter at 1D ( p  < .001) and at 3M ( p  = .007), whereas daytime QTcFri was longer at 1D ( p  < .05) but similar at 3M ( p  = ns) compared to baseline. During the night, changes were observed neither in QTcBaz nor in QTcFri between baseline, 1D, and 3M. Changes in cardiac repolarization after fingolimod initiation were mild and occurred at daytime. Ambiguously, QTcBaz demonstrated shortening, whereas QTcFri showed prolongation in cardiac repolarization after fingolimod initiation. The formula applied for QT-interval correction needs to be taken carefully into account as evaluating pharmacovigilance issues related to fingolimod.

Long QT interval in Turner syndrome--a high prevalence of LQTS gene mutations.

PubMed

Trolle, Christian; Mortensen, Kristian H; Pedersen, Lisbeth N; Berglund, Agnethe; Jensen, Henrik K; Andersen, Niels H; Gravholt, Claus H

2013-01-01

QT-interval prolongation of unknown aetiology is common in Turner syndrome. This study set out to explore the presence of known long QT mutations in Turner syndrome and to examine the corrected QT-interval (QTc) over time and relate the findings to the Turner syndrome phenotype. Adult women with Turner syndrome (n = 88) were examined thrice and 68 age-matched healthy controls were examined once. QTc was measured by one blinded reader (intra-reader variability: 0.7%), and adjusted for influence of heart rate by Bazett's (bQTc) and Hodges's formula (hQTc). The prevalence of mutations in genes related to Long QT syndrome was determined in women with Turner syndrome and a QTc >432.0 milliseconds (ms). Echocardiographic assessment of aortic valve morphology, 24-hour blood pressures and blood samples were done. The mean hQTc in women with Turner syndrome (414.0 ± 25.5 ms) compared to controls (390.4 ± 17.8 ms) was prolonged (p<0.001) and did not change over time (416.9 ± 22.6 vs. 415.6 ± 25.5 ms; p =0.4). 45,X karyotype was associated with increased hQTc prolongation compared to other Turner syndrome karyotypes (418.2 ± 24.8 vs. 407.6 ± 25.5 ms; p = 0.055). In women with Turner syndrome and a bQTc >432 ms, 7 had mutations in major Long QT syndrome genes (SCN5A and KCNH2) and one in a minor Long QT syndrome gene (KCNE2). There is a high prevalence of mutations in the major LQTS genes in women with TS and prolonged QTc. It remains to be settled, whether these findings are related to the unexplained excess mortality in Turner women. NCT00624949. https://register.clinicaltrials.gov/prs/app/action/SelectProtocol/sid/S0001FLI/selectaction/View/ts/3/uid/U000099E.

Characteristics of fin whale vocalizations recorded on instruments in the northeast Pacific Ocean

NASA Astrophysics Data System (ADS)

Weirathmueller, Maria Michelle Josephine

This thesis focuses on fin whale vocalizations recorded on ocean bottom seismometers (OBSs) in the Northeast Pacific Ocean, using data collected between 2003 and 2013. OBSs are a valuable, and largely untapped resource for the passive acoustic monitoring of large baleen whales. This dissertation is divided into three parts, each of which uses the recordings of fin whale vocalizations to better understand their calling behaviors and distributions. The first study describes the development of a technique to extract source levels of fin whale vocalizations from OBS recordings. Source levels were estimated using data collected on a network of eight OBSs in the Northeast Pacific Ocean. The acoustic pressure levels measured at the instruments were adjusted for the propagation path between the calling whales and the instruments using the call location and estimating losses along the acoustic travel path. A total of 1241 calls were used to estimate an average source level of 189 +/-5.8 dB re 1uPa 1m. This variability is largely attributed to uncertainties in the horizontal and vertical position of the fin whale at the time of each call, and the effect of these uncertainties on subsequent calculations. The second study describes a semi-automated method for obtaining horizontal ranges to vocalizing fin whales using the timing and relative amplitude of multipath arrivals. A matched filter is used to detect fin whale calls and pick the relative times and amplitudes of multipath arrivals. Ray-based propagation models are used to predict multipath times and amplitudes as function of range. Because the direct and first multiple arrivals are not always observed, three hypotheses for the paths of the observed arrivals are considered; the solution is the hypothesis and range that optimizes the fit to the data. Ray-theoretical amplitudes are not accurate and solutions are improved by determining amplitudes from the observations using a bootstrap method. Data from ocean bottom seismometers at two locations are used to assess the method: one on the Juan de Fuca Ridge, a bathymetrically complex mid-ocean ridge environment, and the other at a flat sedimented location in the Cascadia Basin. At both sites, the method is reliable up to 4 km range which is sufficient to enable estimates of call density. The third study explores spatial and temporal trends in fin whale calling patterns. The frequency and inter-pulse interval of fin whale 20 Hz vocalizations were observed over 10 years from 2003-2013 on bottom mounted hydrophones and OBSs in the northeast Pacific Ocean. The instrument locations extended from 40°N and 130°W to 125°W with water depths ranging from 1500-4000 m. The inter-pulse interval (IPI) of fin whale song sequences was observed to increase at a rate of 0.59 seconds/year over the decade of observation. During the same time period, peak frequency decreased at a rate of 0.16 Hz/year. Two primary call patterns were observed. During the earlier years, the more commonly observed pattern had a single frequency and single IPI. In later years, a doublet pattern emerged, with two dominant frequencies and two IPIs. Many call sequences in the intervening years appeared to represent a transitional state between the two patterns. The overall trend was consistent across the entire geographical span, although some regional differences exist.

A preliminary study on postmortem interval estimation of suffocated rats by GC-MS/MS-based plasma metabolic profiling.

PubMed

Sato, Takako; Zaitsu, Kei; Tsuboi, Kento; Nomura, Masakatsu; Kusano, Maiko; Shima, Noriaki; Abe, Shuntaro; Ishii, Akira; Tsuchihashi, Hitoshi; Suzuki, Koichi

2015-05-01

Estimation of postmortem interval (PMI) is an important goal in judicial autopsy. Although many approaches can estimate PMI through physical findings and biochemical tests, accurate PMI calculation by these conventional methods remains difficult because PMI is readily affected by surrounding conditions, such as ambient temperature and humidity. In this study, Sprague-Dawley (SD) rats (10 weeks) were sacrificed by suffocation, and blood was collected by dissection at various time intervals (0, 3, 6, 12, 24, and 48 h; n = 6) after death. A total of 70 endogenous metabolites were detected in plasma by gas chromatography-tandem mass spectrometry (GC-MS/MS). Each time group was separated from each other on the principal component analysis (PCA) score plot, suggesting that the various endogenous metabolites changed with time after death. To prepare a prediction model of a PMI, a partial least squares (or projection to latent structure, PLS) regression model was constructed using the levels of significantly different metabolites determined by variable importance in the projection (VIP) score and the Kruskal-Wallis test (P < 0.05). Because the constructed PLS regression model could successfully predict each PMI, this model was validated with another validation set (n = 3). In conclusion, plasma metabolic profiling demonstrated its ability to successfully estimate PMI under a certain condition. This result can be considered to be the first step for using the metabolomics method in future forensic casework.

Comparing neuronal spike trains with inhomogeneous Poisson distribution: evaluation procedure and experimental application in cases of cyclic activity.

PubMed

Fiore, Lorenzo; Lorenzetti, Walter; Ratti, Giovannino

2005-11-30

A procedure is proposed to compare single-unit spiking activity elicited in repetitive cycles with an inhomogeneous Poisson process (IPP). Each spike sequence in a cycle is discretized and represented as a point process on a circle. The interspike interval probability density predicted for an IPP is computed on the basis of the experimental firing probability density; differences from the experimental interval distribution are assessed. This procedure was applied to spike trains which were repetitively induced by opening-closing movements of the distal article of a lobster leg. As expected, the density of short interspike intervals, less than 20-40 ms in length, was found to lie greatly below the level predicted for an IPP, reflecting the occurrence of the refractory period. Conversely, longer intervals, ranging from 20-40 to 100-120 ms, were markedly more abundant than expected; this provided evidence for a time window of increased tendency to fire again after a spike. Less consistently, a weak depression of spike generation was observed for longer intervals. A Monte Carlo procedure, implemented for comparison, produced quite similar results, but was slightly less precise and more demanding as concerns computation time.

Ventricular repolarization alterations in women with angina pectoris and suspected coronary microvascular dysfunction.

PubMed

Dose, Nynne; Michelsen, Marie Mide; Mygind, Naja Dam; Pena, Adam; Ellervik, Christina; Hansen, Peter R; Kanters, Jørgen K; Prescott, Eva; Kastrup, Jens; Gustafsson, Ida; Hansen, Henrik Steen

CMD could be the explanation of angina pectoris with no obstructive CAD and may cause ventricular repolarization changes. We compared T-wave morphology and QTc interval in women with angina pectoris with a control group as well as the associations with CMD. Women with angina pectoris and no obstructive coronary artery disease (n=138) and age-matched controls were compared in regard to QTc interval and morphology combination score (MCS) based on T-wave asymmetry, flatness and presence of T-wave notch. CMD was assessed as a coronary flow velocity reserve (CFVR) by transthoracic echocardiography. Women with angina pectoris had significantly longer QTc intervals (429±20ms) and increased MCS (IQR) (0.73 [0.64-0.80]) compared with the controls (419±20ms) and (0.63 [(0.53-0.73]), respectively (both p<0.001). CFVR was associated with longer QTc interval (p=0.02), but the association was attenuated after multivariable adjustment (p=0.08). This study suggests that women with angina pectoris have alterations in T-wave morphology as well as longer QTc interval compared with a reference population. CMD might be an explanation. Copyright © 2017 Elsevier Inc. All rights reserved.

Adults' age-related differences in strategy perseveration are modulated by response-stimulus intervals and problem features.

PubMed

Lemaire, Patrick; Brun, Fleur

2014-10-01

Ageing results in the tendency of older adults to repeat the same strategy across consecutive problems more often than young adults, even when such strategy perseveration is not appropriate. Here, we examined how these age-related differences in strategy perseveration are modulated by response-stimulus intervals and problem characteristics. We asked participants to select the best strategy while accomplishing a computational estimation task (i.e., provide approximate sums to two-digit addition problems like 38 + 74). We found that participants repeated the same strategy across consecutive problems more often when the duration between their response and next problem display was short (300 ms) than when it was long (1300 ms). We also found more strategy perseverations in older than in young adults under short Response-Stimulus Intervals, but not under long Response-Stimulus Intervals. Finally, age-related differences in strategy perseveration decreased when problem features helped participants to select the best strategy. These modulations of age-related differences in strategy perseveration by response-stimulus intervals and characteristics of target problems are important for furthering our understanding of mechanisms underlying strategy perseveration and, more generally, ageing effects on strategy selection.

Tachycardia-dependent augmentation of "notched J waves" in a general patient population without ventricular fibrillation or cardiac arrest: not a repolarization but a depolarization abnormality?

PubMed

Aizawa, Yoshifusa; Sato, Masahito; Kitazawa, Hitoshi; Aizawa, Yoshiyasu; Takatsuki, Seiji; Oda, Eiji; Okabe, Masaaki; Fukuda, Keiichi

2015-02-01

J waves can be observed in individuals of the general population, but electrocardiographic characteristics are poorly understood. The purpose of this study was to examine the J-wave dynamicity in a general patient population. The responses of J waves (>0.1 mV above the isoelectric line in 2 contiguous leads) to varying RR intervals were analyzed. Patients with aborted sudden cardiac death, documented ventricular fibrillation, or a family history of sudden cardiac death were excluded. The J-wave amplitude was measured at baseline, in beats with short RR intervals in conducted atrial premature beats (APBs) or atrial stimulation during the electrophysiology study, and in the beats next to APBs with prolonged RR intervals. Mainly notched J waves were identified in 94 of 701 (24.5%) general patients (13.4%), and APBs were present in 23 of 94 (24.5%) patients. The mean baseline amplitude of J waves was 0.20 ± 0.06 mV at the baseline RR interval of 853 ± 152 ms, 0.25 ± 0.11 mV at the RR interval in the conducted APB of 545 ± 133 ms (P = .0018), and 0.19 ± 0.08 mV at the RR interval of 1146 ± 314 ms (P = .3102). The clinical characteristics were not different between patients with and without tachycardia-dependent augmentation of J waves. Augmentation of J waves was confirmed by the electrophysiology study: 0.28 ± 0.12 mV vs 0.42 ± 0.11 mV at baseline and in the beats of atrial stimulation, respectively (P = .0001). However, no bradycardia-dependent augmentation (>0.05 mV) was observed. Such tachycardia-dependent augmentation can represent depolarization abnormality rather than repolarization abnormality. J waves in a general patient population were augmented at shorter RR intervals, but not at prolonged RR intervals. Mechanistically, conduction delay is most likely responsible for this. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Characteristics in childhood and adolescence associated with future multiple sclerosis risk in men: cohort study.

PubMed

Gunnarsson, M; Udumyan, R; Bahmanyar, S; Nilsagård, Y; Montgomery, S

2015-07-01

Associations with multiple sclerosis (MS) of living conditions in childhood and characteristics in adolescence including physical fitness, cognitive function and psychological stress resilience were investigated. A cohort of male Swedish residents born 1952-1956 who were included in the Swedish Military Conscription Register was used to create a nested case-control study comprising 628 MS cases and 6187 controls matched on birth year, county of residence and vital status at time of diagnosis. Conscription examination records were linked with other national register data. Conditional logistic regression was used to evaluate associations with MS subsequent to the conscription examination. Men with MS were less likely to be from more crowded households in childhood (>two persons per room) with an adjusted odds ratio of 0.67 (95% confidence interval 0.51-0.86, P = 0.023). They had lower physical working capacity in adolescence with adjusted odds ratio of 0.94 (95% confidence interval 0.89-0.99, P = 0.026). Cognitive function and stress resilience scores displayed no significant differences between cases and controls. Parental occupation in childhood and body mass index in adolescence were not associated with future MS risk. The inverse association of MS risk with higher levels of household crowding may reflect environmental factors such as the pattern of exposure to microorganisms. Lower physical fitness in men at MS risk may indicate a protective effect of exercise or could be due to prodromal disease activity, although there was no association with cognitive function. Poor psychological stress resilience (and thus risk of chronic stress arousal) was not associated with MS. © 2015 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.

Radioimmunoassay and tandem mass spectrometry measurement of bedtime salivary cortisol levels: a comparison of assays to establish hypercortisolism.

PubMed

Baid, Smita K; Sinaii, Ninet; Wade, Matt; Rubino, Domenica; Nieman, Lynnette K

2007-08-01

Although bedtime salivary cortisol measurement has been proposed as the optimal screening test for the diagnosis of Cushing's syndrome, its performance using commercially available assays has not been widely evaluated. Our objective was to compare RIA and tandem mass spectrometry (LC-MS/MS) measurement of salivary cortisol in obese subjects and healthy volunteers. We conducted a cross-sectional prospective study of outpatients. We studied 261 obese subjects (186 female) with at least two additional features of Cushing's syndrome and 60 healthy volunteers (30 female). Subjects provided split bedtime salivary samples for cortisol measurement by commercially available RIA and LC-MS/MS. Results were considered normal or abnormal based on the laboratory reference range. Subjects with abnormal results underwent evaluation for Cushing's syndrome. In paired samples, RIA gave a lower specificity than LC-MS/MS in obese subjects (86 vs. 94%, P = 0.008) but not healthy volunteers (86 vs. 82%, P = 0.71). Among subjects with at least one abnormal result, both values were abnormal in 44% (confidence interval 26-62%) of obese and 75% (confidence interval 33-96%) of healthy volunteers. In obese subjects, salivary cortisol concentrations were less than 4.0 to 643 ng/dl (<0.11-17.7 nmol/liter; normal, < or =100 ng/dl, 2.80 nmol/liter) by LC-MS/MS and less than 50 to 2800 ng/dl (1.4-77.3 nmol/liter; normal, < or =170 ng/dl, 4.7 nmol/liter) by RIA. Cushing's syndrome was not diagnosed in any subject. Salivary cortisol levels should not be used as the sole test to diagnose Cushing's syndrome if laboratory-provided reference ranges are used for diagnostic interpretation.

Pharmacokinetics and repolarization effects of intravenous and transdermal granisetron.

PubMed

Mason, Jay W; Selness, Daniel S; Moon, Thomas E; O'Mahony, Bridget; Donachie, Peter; Howell, Julian

2012-05-15

The need for greater clarity about the effects of 5-HT(3) receptor antagonists on cardiac repolarization is apparent in the changing product labeling across this therapeutic class. This study assessed the repolarization effects of granisetron, a 5-HT(3) receptor antagonist antiemetic, administered intravenously and by a granisetron transdermal system (GTDS). In a parallel four-arm study, healthy subjects were randomized to receive intravenous granisetron, GTDS, placebo, or oral moxifloxacin (active control). The primary endpoint was difference in change from baseline in mean Fridericia-corrected QT interval (QTcF) between GTDS and placebo (ddQTcF) on days 3 and 5. A total of 240 subjects were enrolled, 60 in each group. Adequate sensitivity for detection of QTc change was shown by a 5.75 ms lower bound of the 90% confidence interval (CI) for moxifloxacin versus placebo at 2 hours postdose on day 3. Day 3 ddQTcF values varied between 0.2 and 1.9 ms for GTDS (maximum upper bound of 90% CI, 6.88 ms), between -1.2 and 1.6 ms for i.v. granisetron (maximum upper bound of 90% CI, 5.86 ms), and between -3.4 and 4.7 ms for moxifloxacin (maximum upper bound of 90% CI, 13.45 ms). Day 5 findings were similar. Pharmacokinetic-ddQTcF modeling showed a minimally positive slope of 0.157 ms/(ng/mL), but a very low correlation (r = 0.090). GTDS was not associated with statistically or clinically significant effects on QTcF or other electrocardiographic variables. This study provides useful clarification on the effect of granisetron delivered by GTDS on cardiac repolarization. ©2012 AACR.

In-Hospital Haloperidol Use and Perioperative Changes in QTc-Duration.

PubMed

Blom, M T; Jansen, S; de Jonghe, A; van Munster, B C; de Boer, A; de Rooij, S E; Tan, H L; van der Velde, N

2015-05-01

Haloperidol may prolong ECG QTc-duration but is often prescribed perioperatively to hip-fracture patients. We aimed to determine (1) how QTc-duration changes perioperatively, (2) whether low-dose haloperidol-use influences these changes, and (3) which clinical variables are associated with potentially dangerous perioperative QTc-prolongation (PD-QTc; increase >50 ms or to >500 ms). Prospective cohort study. Tertiary university teaching-hospital. Patients enrolled in a randomized controlled clinical trial of melatonin versus placebo on occurrence of delirium in hip-fracture patients. Data from ECGs made before and after hip surgery (1-3 days and/or 4-6 days post-surgery) were analyzed. QTc-duration was measured by hand, blinded for haloperidol and pre/post-surgery status. Clinical variables were measured at baseline. Mixed model analysis was used to estimate changes in QTc-duration. Risk-factors for PD-QTc were estimated by logistic regression analysis. We included 89 patients (mean age 84 years, 24% male); 39 were treated with haloperidol. Patients with normal pre-surgery QTc-duration (male ≤430 ms, female ≤450 ms) had a significant increase (mean 12 ms, SD 28) in QTc-duration. A significant decrease (mean 19 ms, SD 34) occurred in patients with prolonged pre-surgery QTc-duration (male >450ms, female >470 ms). Haloperidol-use did not influence the perioperative course of the QTc-interval (p=0.351). PD-QTc (n=8) was not associated with any of the measured risk-factors. QTc-duration changed differentially, increasing in patients with normal, but decreasing in patients with abnormal baseline QTc-duration. PD-QTc was not associated with haloperidol-use or other risk-factors. Low-dose oral haloperidol did not affect perioperative QTc-interval.

Low proarrhythmic potential of citalopram and escitalopram in contrast to haloperidol in an experimental whole-heart model.

PubMed

Frommeyer, Gerrit; Brücher, Benedict; von der Ahe, Henning; Kaese, Sven; Dechering, Dirk G; Kochhäuser, Simon; Bogossian, Harilaos; Milberg, Peter; Eckardt, Lars

2016-10-05

In several case reports proarrhythmic effects of citalopram and escitalopram have been reported. Systematic analyses on prorarrhythmic effects of these drugs are not yet available. The aim of the present study was to investigate if application of citalopram, escitalopram or haloperidol provokes polymorphic ventricular tachycardia in a sensitive model of proarrhythmia. In isolated rabbit hearts monophasic action potentials and ECG showed a significant QT-prolongation after application of citalopram (2µM: +47ms, 4µM: +56ms, P<0.05) accompanied by an increase of action potential duration (APD) but not dispersion of repolarization. Reduced potassium concentration in bradycardic AV-blocked hearts provoked early afterdepolarizations (EAD) in 2 of 12 hearts but no polymorphic ventricular tachycardia (pVT). Application of escitalopram also increased QT-interval (2µM: +3ms, 4µM: +30ms, P<0.05) and APD without effects on dispersion. 3 of 10 hearts showed EAD and pVT in 2 of 10 hearts (32 episodes). The results were compared to 12 rabbits treated with haloperidol which led to an increase in QT-interval (1µM:+62ms; 2µM:+96ms; P<0.01), APD and dispersion (1µM:+15ms, 2µM:+40ms; P<0.01) and induced EAD in all 12 and pVT in 10 of 12 hearts (152 episodes). Citalopram and escitalopram demonstrated a rather safe electrophysiologic profile despite significant QT prolongation. In contrast, haloperidol led to significant increase of dispersion of repolarization while this parameter remained stable under the influence of citalopram or escitalopram. These results imply that application of citalopram or escitalopram is not as proarrhythmic as some case reports might suggest while haloperidol is torsadogenic. Copyright © 2016 Elsevier B.V. All rights reserved.

Early life stress impairs social recognition due to a blunted response of vasopressin release within the septum of adult male rats.

PubMed

Lukas, Michael; Bredewold, Remco; Landgraf, Rainer; Neumann, Inga D; Veenema, Alexa H

2011-07-01

Early life stress poses a risk for the development of psychopathologies characterized by disturbed emotional, social, and cognitive performance. We used maternal separation (MS, 3h daily, postnatal days 1-14) to test whether early life stress impairs social recognition performance in juvenile (5-week-old) and adult (16-week-old) male Wistar rats. Social recognition was tested in the social discrimination test and defined by increased investigation by the experimental rat towards a novel rat compared with a previously encountered rat. Juvenile control and MS rats demonstrated successful social recognition at inter-exposure intervals of 30 and 60 min. However, unlike adult control rats, adult MS rats failed to discriminate between a previously encountered and a novel rat after 60 min. The social recognition impairment of adult MS rats was accompanied by a lack of a rise in arginine vasopressin (AVP) release within the lateral septum seen during social memory acquisition in adult control rats. This blunted response of septal AVP release was social stimulus-specific because forced swimming induced a rise in septal AVP release in both control and MS rats. Retrodialysis of AVP (1 μg/ml, 3.3 μl/min, 30 min) into the lateral septum during social memory acquisition restored social recognition in adult MS rats at the 60-min interval. These studies demonstrate that MS impairs social recognition performance in adult rats, which is likely caused by blunted septal AVP activation. Impaired social recognition may be linked to MS-induced changes in other social behaviors like aggression as shown previously. Copyright © 2010 Elsevier Ltd. All rights reserved.

Accessory pathway location affects brain natriuretic peptide level in patients with Wolff-Parkinson-White syndrome.

PubMed

Nakatani, Yosuke; Kumagai, Koji; Naito, Shigeto; Nakamura, Kohki; Minami, Kentaro; Nakano, Masahiro; Sasaki, Takehito; Kinugawa, Koichiro; Oshima, Shigeru

2017-01-01

The purpose of this study was to investigate the relationship between the accessory pathway location and brain natriuretic peptide (BNP) level in patients with Wolff-Parkinson-White (WPW) syndrome. We divided 102 WPW syndrome patients with normal left ventricular systolic function into four groups: those with manifest right (MR, n = 14), manifest septal (MS, n = 11), manifest left (ML, n = 30), and concealed (C, n = 47) accessory pathways. BNP level and electrophysiological properties, including difference in timing of the ventricular electrogram between the His bundle area and the distal coronary sinus area (His-CS delay), which indicate intraventricular dyssynchrony, were compared. BNP levels (pg/dl) were higher in the MR and MS groups than in the ML and C groups (MR, 64 ± 58; MS, 55 ± 45; ML, 17 ± 15; C, 25 ± 21; P < 0.001). AV intervals (ms) were shorter in the MR and MS groups than in the ML and C groups (MR, 76 ± 16; MS, 83 ± 6; ML, 101 ± 19; C, 136 ± 20; P < 0.001). His-CS delay (ms) was longer in the MR group than in the other groups (MR, 50 ± 15; MS, 21 ± 7; ML, 23 ± 10; C, 19 ± 8; P < 0.001). The AV interval (P < 0.01) and the His-CS delay (P < 0.001) were negatively and positively correlated, respectively, with the BNP level. Anterograde conduction with a right or septal accessory pathway increased the BNP level in WPW syndrome patients with normal cardiac function.

Factors associated with recently transmitted Mycobacterium tuberculosis strain MS0006 in Hinds County, Mississippi.

PubMed

Temple, Brian; Kwara, Awewura; Sunesara, Imran; Mena, Leandro; Dobbs, Thomas; Henderson, Harold; Holcomb, Mike; Webb, Risa

2011-12-01

The objective of this study was to investigate risk factors associated with tuberculosis (TB) transmission that was caused by Mycobacterium tuberculosis strain MS0006 from 2004 to 2009 in Hinds County, Mississippi. DNA fingerprinting using spoligotyping, mycobacterial interspersed repetitive unit, and IS6110-based restriction fragment length polymorphism of culture-confirmed cases of TB was performed. Clinical and demographic factors associated with strain MS0006 were analyzed by univariate and multivariate analysis. Of the 144 cases of TB diagnosed during the study period, 117 were culture positive with fingerprints available. There were 48 different strains, of which 6 clustered strains were distributed among 74 patients. The MS0006 strain accounted for 46.2% of all culture-confirmed cases. Risk factors for having the MS0006 strain in a univariate analysis included homelessness, HIV co-infection, sputum smear negativity, tuberculin skin test negativity, and noninjectable drug use. Multivariate analysis identified homelessness (odds ratio 7.88, 95% confidence interval 2.90-21.35) and African American race (odds ratio 5.80, 95% confidence interval 1.37-24.55) as independent predictors of having TB caused by the MS0006 strain of M. tuberculosis. Our findings suggest that a majority of recently transmitted TB in the studied county was caused by the MS0006 strain. African American race and homelessness were significant risk factors for inclusion in the cluster. Molecular epidemiology techniques continue to provide in-depth analysis of disease transmission and play a vital role in effective contact tracing and interruption of ongoing transmission.

Palbociclib has no clinically relevant effect on the QTc interval in patients with advanced breast cancer.

PubMed

Durairaj, Chandrasekar; Ruiz-Garcia, Ana; Gauthier, Eric R; Huang, Xin; Lu, Dongrui R; Hoffman, Justin T; Finn, Richard S; Joy, Anil A; Ettl, Johannes; Rugo, Hope S; Zheng, Jenny; Wilner, Keith D; Wang, Diane D

2018-03-01

The aim of this study was to assess the potential effects of palbociclib in combination with letrozole on QTc. PALOMA-2, a phase 3, randomized, double-blind, placebo-controlled trial, compared palbociclib plus letrozole with placebo plus letrozole in postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. The study included a QTc evaluation substudy carried out as a definitive QT interval prolongation assessment for palbociclib. Time-matched triplicate ECGs were performed at 0, 2, 4, 6, and 8 h at baseline (Day 0) and on Cycle 1 Day 14. Additional ECGs were collected from all patients for safety monitoring. The QT interval was corrected for heart rate using Fridericia's correction (QTcF), Bazett's correction (QTcB), and a study-specific correction factor (QTcS). In total, 666 patients were randomized 2 : 1 to palbociclib plus letrozole or placebo plus letrozole. Of these, 125 patients were enrolled in the QTc evaluation substudy. No patients in the palbociclib plus letrozole arm of the substudy (N=77) had a maximum postbaseline QTcS or QTcF value of ≥ 480 ms, or a maximum increase from clock time-matched baseline for QTcS or QTcF values of ≥ 60 ms. The upper bounds of the one-sided 95% confidence interval for the mean change from time-matched baseline for QTcS, QTcF, and QTcB at all time points and at steady-state Cmax following repeated administration of 125 mg palbociclib were less than 10 ms. Palbociclib, when administered with letrozole at the recommended therapeutic dosing regimen, did not prolong the QT interval to a clinically relevant extent.

Astronomical timescale calibration for the Permian-Triassic boundary transition interval from global correlation of cyclic marine sequences

NASA Astrophysics Data System (ADS)

Huang, C.; Hinnov, L. A.; Tong, J.; Chen, Z.

2011-12-01

The mass extinctions near the Permian-Triassic boundary (PTB) resulted in the greatest dying of life on Earth. The cause of this catastrophe remains enigmatic. High-resolution chronology is crucial to understanding the recorded pattern of biotic evolution and possible causes for the extinctions. Magnetic susceptibility (MS) data from Shangsi, South China shows evidence for astronomical forcing through the PTB interval, with strong 405-kyr cycling. This allows development of an astrochronology for the PTB interval based on the 405-kyr orbital eccentricity metronome that has been proposed for the Mesozoic timescale. Radioisotope dating combined with the 405-kyr tuned MS series from Shangsi shows that the 405-kyr-cycle predominates throughout the PTB interval. In the Permian segment, ~100-kyr cyclicity dominates, and the 100-kyr-scale MS maxima correlate with high-amplitude precession-scale MS variations. Minima in the ~1.5-Myr, 405-kyr and ~100-kyr cycles converge at 252.6 Ma, approximately 200 kyr before the onset of the main mass extinction near the PTB. In the Triassic aftermath, the recorded astronomical signal is different, with predominant 405-kyr cycles and loss of 100 kyr cyclicity, and appearance of ~33 kyr (obliquity scale) cyclicity; 100-kyr cyclicity strengthens again 2 Myr later. This pattern indicates a change in the response of the depositional environment (or magnetic susceptibility) to astronomical forcing before and after the mass extinction interval. The astrochronology interpolates the timescale between the radioisotopically determined absolute dates; this facilitates estimation of ages for specific events in the PTB crisis, including magnetic reversals, biozone boundaries, and the mass extinctions. An estimated ~700 kyr duration for the Mass Extinction Interval (MEI) at Shangsi based on the 405-kyr tuning is supported by eccentricity-tuned estimates of three other sections in China (Meishan, Huangzhishan, and Heping), and two Alpine sections (Gartnerkofel, Austria and Bulla, Italy) from the eastern and western margins of the Palaeo-Tethys Ocean during PTB time. This suggests that the PTB mass extinctions were not the result of a single catastrophic event. Siberian trap volcanism was largely synchronous with the MEI and appears to be the most likely cause of the mass extinctions; astronomically paced climate change may also have played a role.

Temporal Ventriloquism in a Purely Temporal Context

ERIC Educational Resources Information Center

Hartcher-O'Brien, Jessica; Alais, David

2011-01-01

This study examines how audiovisual signals are combined in time for a temporal analogue of the ventriloquist effect in a purely temporal context, that is, no spatial grounding of signals or other spatial facilitation. Observers were presented with two successive intervals, each defined by a 1250-ms tone, and indicated in which interval a brief…

Measurement of Phonated Intervals during Four Fluency-Inducing Conditions

ERIC Educational Resources Information Center

Davidow, Jason H.; Bothe, Anne K.; Andreatta, Richard D.; Ye, Jun

2009-01-01

Purpose: Previous investigations of persons who stutter have demonstrated changes in vocalization variables during fluency-inducing conditions (FICs). A series of studies has also shown that a reduction in short intervals of phonation, those from 30 to 200 ms, is associated with decreased stuttering. The purpose of this study, therefore, was to…

[Evaluation of autonomic nervous system function with heart rate variability analysis in patients with hyperthyroidism and during euthyroidism after pharmacologic and surgical treatment].

PubMed

Barczyński, M; Tabor, S; Thor, P

1997-01-01

The aim of the present study was both to estimate autonomic nervous system (ANS) function in patients with hyperthyroidism by the heart rate variability (HRV) analysis and to evaluate the impact of pharmacological and surgical treatment on the ANS function. Analysis of the HRV underwent 10 female patients in course of thyreotoxicosis and after reaching full clinical and biochemical euthyroidism, after pharmacological therapy and in month after surgical treatment. The 10 minutes records at rest, in horizontal position were evaluated. The HRV parameters like mean of the heart rate, mean of RR intervals, standard deviation of all normal RR intervals (SDNN), range of the heart rate variability, low frequency (LF), high frequency (HF) components of the heart rate power spectral density and LF/HF ratio were assessed. The results were compared to those obtained from 10 age-, sex-, and body mass index-matched control subjects. The statistical significance (p < 0.05) was found in reduction of range of RR intervals, in increase of LF/HF ratio and in decrease of SDNN in hyperthyroidism in comparison to the control group (151.6/346.8 ms; 2.4/0.74; 24.4/57.2 ms2). In course of pharmacological euthyroidism there were statistically significant (p < 0.05) increase of range of RR intervals, reduction of LF/HF ratio and increase of SDNN in comparison to hyperthyroidism (270/151.6 ms; 0.995/2.4; 39/24.4 ms2). In euthyroidism after surgical treatment all the above parameters kept the similar levels as in pharmacological euthyroidism (no statistical significance for p < 0.05). On the base of the outcomes it was considered that in hyperthyroid patients there is advantage of sympathetic part of ANS over parasympathetic one which is due to sharp reduction of parasympathetic system activity. Pharmacological therapy with thyreostatics normalises balance of ANS to the level of the control group and after surgical treatment the balance keeps the same. Moreover, in the estimation of ANS as important as LF/HF ratio is the mean range of RR intervals.

Gender identity disorders and multiple sclerosis risk: A national record-linkage study.

PubMed

Pakpoor, Julia; Wotton, Clare J; Schmierer, Klaus; Giovannoni, Gavin; Goldacre, Michael J

2016-11-01

An altered balance of gonadal hormones in males with gender identity disorders (GIDs) may increase multiple sclerosis (MS) risk both inherently and secondary to treatment in undergoing male-to-female conversion. We investigated any association between GIDs and MS through analysis of record-linked hospital statistics. Analysis of English Hospital Episode Statistics, 1999-2012. The adjusted rate ratio (RR) of MS following GIDs in males was 6.63 (95% confidence interval (95% CI) = 1.81-17.01, p = 0.0002). The RR of MS following GIDs in females was 1.44 (95% CI = 0.47-3.37, p = 0.58). We report a strong association between GIDs and MS in male-to-females, supporting a potential role for low testosterone and/or feminising hormones on MS risk in males. © The Author(s), 2016.

Classic conditioning in aged rabbits: delay, trace, and long-delay conditioning.

PubMed

Solomon, P R; Groccia-Ellison, M E

1996-06-01

Young (0.5 years) and aged (2+, 3+, and 4+ years) rabbits underwent acquisition of the classically conditioned nictitating membrane response in a delay (500-ms conditioned stimulus [CS], 400-ms interstimulus interval [ISI]), long-delay (1,000-ms CS, 900-ms ISI), or trace (500-ms CS, 400-ms stimulus-free period) paradigm. Collapsing across age groups, there is a general tendency for animals to acquire trace conditioning more slowly than delay conditioning. Collapsing across conditioning paradigms, there is a general tendency for aged animals to acquire more slowly than younger animals. Of greater significance, however, are the age differences in the different conditioning paradigms. In the delay and long-delay paradigms, significant conditioning deficits first appeared in the 4(+)-year-old group. In the trace conditioning paradigm, significant conditioning deficits became apparent in the 2(+)-year-old animals.

The DPP-4 inhibitor linagliptin does not prolong the QT interval at therapeutic and supratherapeutic doses

PubMed Central

Ring, Arne; Port, Andreas; Graefe-Mody, E Ulrike; Revollo, Ivette; Iovino, Mario; Dugi, Klaus A

2011-01-01

AIM To evaluate the potential effects of therapeutic and supratherapeutic doses of linagliptin (BI 1356) on the QT/QTc interval in healthy subjects. METHODS The study was a randomized, double-blind, placebo-controlled, four-period crossover study using single oral doses of linagliptin (5 mg and 100 mg), moxifloxacin (400 mg) and placebo. Electrocardiogram (ECG) profiles using triplicates of 12-lead 10-s ECGs were digitally recorded pre-dose and after drug administration. The mean change from baseline (MCfB) of the individually heart rate corrected QT interval (QTcI) between 1 and 4 h postdrug administration was the primary end point. Blood samples to measure plasma concentrations of linagliptin and its main metabolite were also obtained. RESULTS Forty-four Caucasian subjects (26 male) entered the study and 43 subjects completed the study as planned in the protocol. Linagliptin was not associated with an increase in the baseline-adjusted mean QTcI, at any time point. The placebo-corrected MCfB of QTcI was −1.1 (90% CI −2.7, 0.5) ms and −2.5 (–4.1, –0.9) ms for linagliptin 5 mg and 100 mg, respectively, thus within the non-inferiority margin of 10 ms according to ICH E14. Linagliptin was well tolerated; the assessment of ECGs and other safety parameters gave no clinically relevant findings at either dose tested. Maximum plasma concentrations after administration of 100-mg linagliptin were ∼24-fold higher than those observed previously for chronic treatment with the therapeutic 5-mg dose. Assay sensitivity was confirmed by a placebo-corrected MCfB of QTcI with moxifloxacin of 6.9 (90% CI 5.4, 8.5) ms. CONCLUSIONS Therapeutic and significantly supratherapeutic exposure to linagliptin is not associated with QT interval prolongation. PMID:21306414

Obstructive sleep apnea is associated with increased QT corrected interval dispersion: the effects of continuous positive airway pressure.

PubMed

Bilal, Nagihan; Dikmen, Nursel; Bozkus, Fulsen; Sungur, Aylin; Sarica, Selman; Orhan, Israfil; Samur, Anil

2017-03-31

Severe obstructive sleep apnea (OSA) is associated with increased QT corrected interval dispersion (QTcd) and continuous positive airway pressure (CPAP) is thought to improve this arrhythmogenic marker. The aim of the study was to determine the decrease of ratio of cardiovascular risk in patients with obstructive sleep apnea. The study included 65 patients with severe OSA who had an apnea-hypopnea index (AHI) score of >30. Each patient underwent 12-channel electrocardiogram (ECG) monitoring and polysomnography. Patients with an AHI score of <5 were used as the control group. The control group also underwent ECG monitoring and polysomnography testing. The QTcd levels of both groups were calculated. Three months after CPAP treatment, ECG recordings were obtained from the 65 patients with severe OSA again, and their QTcd values were calculated. There were 44 male and 21 female patients with severe OSA syndrome. The age, gender, body mass index, initial saturation, minimum saturation, average saturation, and desaturation index were determined in both groups. The QTc intervals of the OSA patients (62.48±16.29ms) were significantly higher (p=0.001) than those of the control group (29.72±6.30ms). There were statistically significant differences between the QTc values before and after the CPAP treatment, with pretreatment QTc intervals of 62.48±16.29ms and 3-month post-treatment values of 41.42±16.96ms (p=0.001). There was a positive and significant correlation between QTcd periods and the AHI and hypopnea index (HI) in OSA patients (p=0.001; r=0.71; p=0.001; r=0.679, respectively). CPAP treatment reduced the QTcd in patients with severe OSA. In addition, shortening the QTcd periods in patients with severe OSA may reduce their risk of arrhythmias and cardiovascular disease. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Influence of gender and types of sports training on QT variables in young elite athletes.

PubMed

Omiya, Kazuto; Sekizuka, Hiromitsu; Kida, Keisuke; Suzuki, Kengo; Akashi, Yoshihiro J; Ohba, Haruo; Musha, Haruki

2014-01-01

Influence of gender and sports training on QT variables such as QT interval and dispersion (QT dispersion: QTD) in young elite athletes were evaluated. Subjects included 104 male and 97 female Japanese elite athletes (mean age 21.6 years). Sports included basketball, fencing, gymnastics, judo, swimming, tennis, track and field and volleyball. Age-matched healthy non-athletes (32 men and 20 women) were enrolled as controls. QT measurements were manually obtained from a 12-lead resting electrocardiogram and QTD was calculated as the difference between the longest and shortest QT intervals. A corrected QT interval (QTc) was obtained using Bazett's formula. Subjects were divided into two groups; an endurance training group and a static training group on the basis of their training types. Maximum and minimum QTc were significantly longer in female athletes than in male athletes (max: 414.2 vs. 404.5 ms, min: 375.1 vs. 359.2 ms, p<0.0001 respectively), whereas QTc dispersion (QTcD) was shorter in female athletes than in male athletes (39.2 vs. 45.3 ms, p<0.0001). QTcD was significantly shorter in female athletes than in the female control group (39.2 vs. 45.2 ms, p<0.05). However, no statistically significant difference was observed between male athletes and the male control group. Male gymnasts exhibited significantly longer QTcD than the control group (p<0.01), but female gymnasts had significantly shorter QTcD than the control group (p<0.05). Maximum QTc intervals were prolonged in the male static training group compared with non-athletes, and QTcDs in the static training group were prolonged compared with the endurance training group. However, no significant difference was observed in the female group. In conclusion, both gender and different characteristics of sports training may affect QT variables even in young elite athletes. Vigorous static exercise training may independently prolong QT variables.

Enhanced Laser-Induced Breakdown Spectroscopy By Second-Pulse Selective Wavelength Excitation

NASA Astrophysics Data System (ADS)

Vidal, F.; Chaker, M.; Goueguel, C.; Laville, S.; Loudyi, H.; Rifai, K.; Sabsabi, M.

2008-09-01

We investigate the use of a second laser with a selected wavelength to improve the limit of detection (LoD) of trace elements in the Laser-Induced Breakdown Spectroscopy (LIBS) technique. We consider the combination of LIBS with Laser-Induced Fluorescence (LIF), in which the second laser is used to excite trace elements in the plasma. The influence of the main experimental parameters on the trace elements LIF signal, namely the ablation fluence, the excitation energy, and the inter-pulse delay, was studied experimentally and a physical interpretation of the results was presented. For illustrative purpose we considered detection of Pb in brass samples and in water. The plasma was produced by a Q-switched Nd:YAG laser and then re-excited by a nanosecond optical parametric oscillator laser. We found out that the optimal conditions for our experimental set-up were obtained for relatively weak ablation fluence of 2-3 J/cm2 and inter-pulse delay of 5-10 μs. Using the LIBS-LIFS technique, a single-shot LoD for detection of lead of about 1.5 part per million (ppm) was obtained for solids and 0.5 ppm for liquids. These LoDs represent an improvement of about two orders of magnitude with respect to LIBS. We also discuss resonance-enhanced LIBS (RELIBS), in which the second laser excites the main plasma component instead of the impurities. For the set of parameters used the RELIBS, Pb signal does not differ significantly from the LIBS signal except at low ablation fluence.

High-intensity interval training improves inflammatory and adipokine profiles in postmenopausal women with metabolic syndrome.

PubMed

Steckling, Flávia Mariel; Farinha, Juliano Boufleur; Figueiredo, Felipe da Cunha; Santos, Daniela Lopes Dos; Bresciani, Guilherme; Kretzmann, Nélson Alexandre; Stefanello, Sílvio Terra; Courtes, Aline Alves; Beck, Maristela de Oliveira; Sangoi Cardoso, Manuela; Duarte, Marta Maria Medeiros Frescura; Moresco, Rafael Noal; Soares, Félix Alexandre Antunes

2018-02-12

This study investigate the effects of high-intensity interval training (HIIT) on systemic levels of inflammatory and hormonal markers in postmenopausal women with metabolic syndrome (MS). Fifteen postmenopausal women with MS completed the training on treadmills. Functional, body composition parameters, maximal oxygen uptake (VO 2 max), and lipid profile were assessed before and after HIIT. Serum or plasma levels of cytokines and hormonal markers were measured along the intervention. The analysis of messenger RNA (mRNA) expression of these cytokines was performed in peripheral blood mononuclear cells (PBMC). VO 2 max and some anthropometric parameters were improved after HIIT, while decreased levels of proinflammatory markers and increased levels of interleukin-10 (IL-10) were also found. Adipokines were also modulated after 12 weeks or training. The mRNA expression of the studied genes was unchanged after HIIT. In conclusion, HIIT benefits inflammatory and hormonal axis on serum or plasma samples, without changes on PBMC of postmenopausal MS patients.

A Double-Coil TMS Method to Assess Corticospinal Excitability Changes at a Near-Simultaneous Time in the Two Hands during Movement Preparation

PubMed Central

Wilhelm, Emmanuelle; Quoilin, Caroline; Petitjean, Charlotte; Duque, Julie

2016-01-01

Background: Many previous transcranial magnetic stimulation (TMS) studies have investigated corticospinal excitability changes occurring when choosing which hand to use for an action, one of the most frequent decision people make in daily life. So far, these studies have applied single-pulse TMS eliciting motor-evoked potential (MEP) in one hand when this hand is either selected or non-selected. Using such method, hand choices were shown to entail the operation of two inhibitory mechanisms, suppressing MEPs in the targeted hand either when it is non-selected (competition resolution, CR) or selected (impulse control, IC). However, an important limitation of this “Single-Coil” method is that MEPs are elicited in selected and non-selected conditions during separate trials and thus those two settings may not be completely comparable. Moreover, a more important problem is that MEPs are computed in relation to the movement of different hands. The goal of the present study was to test a “Double-Coil” method to evaluate IC and CR preceding the same hand responses by applying Double-Coil TMS over the two primary motor cortices (M1) at a near-simultaneous time (1 ms inter-pulse interval). Methods: MEPs were obtained in the left (MEPLEFT) and right (MEPRIGHT) hands while subjects chose between left and right hand key-presses in blocks using a Single-Coil or a Double-Coil method; in the latter blocks, TMS was either applied over left M1 first (TMSLRM1 group, n = 12) or right M1 first (TMSRLM1 group, n = 12). Results: MEPLEFT were suppressed preceding both left (IC) and right (CR) hand responses whereas MEPRIGHT were only suppressed preceding left (CR) but not right (IC) hand responses. This result was observed regardless of whether Single-Coil or Double-Coil TMS was applied in the two subject groups. However, in the TMSLRM1 group, the MEP suppression was attenuated in Double-Coil compared to Single-Coil blocks for both IC and CR, when probed with MEPLEFT (elicited by the second pulse). Conclusions: Although Double-Coil TMS may be a reliable method to assess bilateral motor excitability provided that a RM1-LM1 pulse order is used, further experiments are required to understand the reduced MEPLEFT changes in Double-Coil blocks when the LM1-RM1 pulse order was used. PMID:27014020

Sparse and Specific Coding during Information Transmission between Co-cultured Dentate Gyrus and CA3 Hippocampal Networks

PubMed Central

Poli, Daniele; Thiagarajan, Srikanth; DeMarse, Thomas B.; Wheeler, Bruce C.; Brewer, Gregory J.

2017-01-01

To better understand encoding and decoding of stimulus information in two specific hippocampal sub-regions, we isolated and co-cultured rat primary dentate gyrus (DG) and CA3 neurons within a two-chamber device with axonal connectivity via micro-tunnels. We tested the hypothesis that, in these engineered networks, decoding performance of stimulus site information would be more accurate when stimuli and information flow occur in anatomically correct feed-forward DG to CA3 vs. CA3 back to DG. In particular, we characterized the neural code of these sub-regions by measuring sparseness and uniqueness of the responses evoked by specific paired-pulse stimuli. We used the evoked responses in CA3 to decode the stimulation sites in DG (and vice-versa) by means of learning algorithms for classification (support vector machine, SVM). The device was placed over an 8 × 8 grid of extracellular electrodes (micro-electrode array, MEA) in order to provide a platform for monitoring development, self-organization, and improved access to stimulation and recording at multiple sites. The micro-tunnels were designed with dimensions 3 × 10 × 400 μm allowing axonal growth but not migration of cell bodies and long enough to exclude traversal by dendrites. Paired-pulse stimulation (inter-pulse interval 50 ms) was applied at 22 different sites and repeated 25 times in each chamber for each sub-region to evoke time-locked activity. DG-DG and CA3-CA3 networks were used as controls. Stimulation in DG drove signals through the axons in the tunnels to activate a relatively small set of specific electrodes in CA3 (sparse code). CA3-CA3 and DG-DG controls were less sparse in coding than CA3 in DG-CA3 networks. Using all target electrodes with the three highest spike rates (14%), the evoked responses in CA3 specified each stimulation site in DG with optimum uniqueness of 64%. Finally, by SVM learning, these evoked responses in CA3 correctly decoded the stimulation sites in DG for 43% of the trials, significantly higher than the reverse, i.e., how well-recording in DG could predict the stimulation site in CA3. In conclusion, our co-cultured model for the in vivo DG-CA3 hippocampal network showed sparse and specific responses in CA3, selectively evoked by each stimulation site in DG. PMID:28321182

A Model for the Fast Synchronous Oscillations of Firing Rate in Rat Suprachiasmatic Nucleus Neurons Cultured in a Multielectrode Array Dish

PubMed Central

Stepanyuk, Andrey R.; Belan, Pavel V.; Kononenko, Nikolai I.

2014-01-01

When dispersed and cultured in a multielectrode dish (MED), suprachiasmatic nucleus (SCN) neurons express fast oscillations of firing rate (FOFR; fast relative to the circadian cycle), with burst duration ∼10 min, and interburst interval varying from 20 to 60 min in different cells but remaining nevertheless rather regular in individual cells. In many cases, separate neurons in distant parts of the 1 mm recording area of a MED exhibited correlated FOFR. Neither the mechanism of FOFR nor the mechanism of their synchronization among neurons is known. Based on recent data implicating vasoactive intestinal polypeptide (VIP) as a key intercellular synchronizing agent, we built a model in which VIP acts as both a feedback regulator to generate FOFR in individual neurons, and a diffusible synchronizing agent to produce coherent electrical output of a neuronal network. In our model, VIP binding to its (VPAC2) receptors acts through Gs G-proteins to activate adenylyl cyclase (AC), increase intracellular cAMP, and open cyclic-nucleotide-gated (CNG) cation channels, thus depolarizing the cell and generating neuronal firing to release VIP. In parallel, slowly developing homologous desensitization and internalization of VPAC2 receptors terminates elevation of cAMP and thereby provides an interpulse silent interval. Through mathematical modeling, we show that this VIP/VPAC2/AC/cAMP/CNG-channel mechanism is sufficient for generating reliable FOFR in single neurons. When our model for FOFR is combined with a published model of synchronization of circadian rhythms based on VIP/VPAC2 and Per gene regulation synchronization of circadian rhythms is significantly accelerated. These results suggest that (a) auto/paracrine regulation by VIP/VPAC2 and intracellular AC/cAMP/CNG-channels are sufficient to provide robust FOFR and synchrony among neurons in a heterogeneous network, and (b) this system may also participate in synchronization of circadian rhythms. PMID:25192180

Dissociable effects of inter-stimulus interval and presentation duration on rapid face categorization.

PubMed

Retter, Talia L; Jiang, Fang; Webster, Michael A; Rossion, Bruno

2018-04-01

Fast periodic visual stimulation combined with electroencephalography (FPVS-EEG) has unique sensitivity and objectivity in measuring rapid visual categorization processes. It constrains image processing time by presenting stimuli rapidly through brief stimulus presentation durations and short inter-stimulus intervals. However, the selective impact of these temporal parameters on visual categorization is largely unknown. Here, we presented natural images of objects at a rate of 10 or 20 per second (10 or 20 Hz), with faces appearing once per second (1 Hz), leading to two distinct frequency-tagged EEG responses. Twelve observers were tested with three squarewave image presentation conditions: 1) with an ISI, a traditional 50% duty cycle at 10 Hz (50-ms stimulus duration separated by a 50-ms ISI); 2) removing the ISI and matching the rate, a 100% duty cycle at 10 Hz (100-ms duration with 0-ms ISI); 3) removing the ISI and matching the stimulus presentation duration, a 100% duty cycle at 20 Hz (50-ms duration with 0-ms ISI). The face categorization response was significantly decreased in the 20 Hz 100% condition. The conditions at 10 Hz showed similar face-categorization responses, peaking maximally over the right occipito-temporal (ROT) cortex. However, the onset of the 10 Hz 100% response was delayed by about 20 ms over the ROT region relative to the 10 Hz 50% condition, likely due to immediate forward-masking by preceding images. Taken together, these results help to interpret how the FPVS-EEG paradigm sets temporal constraints on visual image categorization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Onset of multiple sclerosis before adulthood leads to failure of age-expected brain growth

PubMed Central

Aubert-Broche, Bérengère; Fonov, Vladimir; Narayanan, Sridar; Arnold, Douglas L.; Araujo, David; Fetco, Dumitru; Till, Christine; Sled, John G.; Collins, D. Louis

2014-01-01

Objective: To determine the impact of pediatric-onset multiple sclerosis (MS) on age-expected brain growth. Methods: Whole brain and regional volumes of 36 patients with relapsing-remitting MS onset prior to 18 years of age were segmented in 185 longitudinal MRI scans (2–11 scans per participant, 3-month to 2-year scan intervals). MRI scans of 25 age- and sex-matched healthy normal controls (NC) were also acquired at baseline and 2 years later on the same scanner as the MS group. A total of 874 scans from 339 participants from the NIH-funded MRI study of normal brain development acquired at 2-year intervals were used as an age-expected healthy growth reference. All data were analyzed with an automatic image processing pipeline to estimate the volume of brain and brain substructures. Mixed-effect models were built using age, sex, and group as fixed effects. Results: Significant group and age interactions were found with the adjusted models fitting brain volumes and normalized thalamus volumes (p < 10−4). These findings indicate a failure of age-normative brain growth for the MS group, and an even greater failure of thalamic growth. In patients with MS, T2 lesion volume correlated with a greater reduction in age-expected thalamic volume. To exclude any scanner-related influence on our data, we confirmed no significant interaction of group in the adjusted models between the NC and NIH MRI Study of Normal Brain Development groups. Conclusions: Our results provide evidence that the onset of MS during childhood and adolescence limits age-expected primary brain growth and leads to subsequent brain atrophy, implicating an early onset of the neurodegenerative aspect of MS. PMID:25378667

Application of liquid chromatography-tandem mass spectrometry in the diagnosis and follow-up of maple syrup urine disease in a Chinese population.

PubMed

Lin, Na; Ye, Jun; Qiu, Wenjuan; Han, Lianshu; Zhang, Huiwen; Gu, Xuefan

2013-01-01

Maple syrup urine disease (MSUD) is an inherited disorder caused by a deficiency of the mitochondrial branched-chain keto acid dehydrogenase complex. We investigated whether liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a more reliable and accurate method than MS/MS in the diagnosis and management of patients with MSUD in a Chinese population. A total of 370 dried blood spots (DBS) from healthy neonates, 44 DBS specimens from phenylketonuria neonates, and 38 DBS samples from 10 MSUD patients were retrospectively tested using the LC-MS/MS method. The results were compared with those obtained by the MS/MS method. The reference intervals of branched-chain amino acids (BCAAs) and alloiosleucine (Allo-Ile) were estimated for both sexes. In classic MSUD patients, Allo-Ile was markedly elevated (average of 136 μmol/L, which was significantly higher than the normal value, <5 μmol/L). The averages of BCAAs were also markedly elevated continually during the treatment. The application of the LC-MS/MS method in the measurement of Allo-Ile and BCAAs in DBS is more useful for diagnosing and managing classic MSUD than the MS/MS method.

Effect of PR Interval on Outcomes Following Cardiac Resynchronization Therapy: A Secondary Analysis of the COMPANION Trial.

PubMed

Lin, Jeffrey; Buhr, Kevin A; Kipp, Ryan

2017-02-01

Prolonged PR intervals may impair atrioventricular mechanical coupling and adversely affect cardiac performance. We hypothesize that patients with advanced systolic heart failure, wide QRS complexes, and prolonged PR intervals will have improved survival from CRT-D regardless of whether left bundle branch block (LBBB) or non-LBBB is present. A total of 308 patients enrolled in the optimal pharmacologic therapy (OPT) and 595 patients in the cardiac resynchronization therapy with defibrillation (CRT-D) arms of the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure trial were stratified according to normal (≤230 ms) or prolonged PR interval (>230 ms). The incidence of all-cause mortality (ACM) or hospitalization (primary endpoint) and ACM (secondary endpoint) was compared using Kaplan-Meier curves. Cox proportional hazards models for the primary and secondary endpoints were fit with LBBB status and baseline PR interval. CRT-D treatment reduced both hospitalization/ACM (P = 0.002) and ACM (P = 0.003) compared to OPT. However, CRT-D was increasingly more effective in reducing ACM hazard in patients with longer baseline PR intervals (P = 0.002) regardless of LBBB status. In particular, in the prolonged baseline PR interval subgroup, ACM was reduced with CRT-D compared to OPT (P = 0.001) with little evidence of ACM reduction in the normal PR subgroup (P = 0.07). In patients with advanced systolic heart failure, wide QRS complexes, and prolonged PR intervals, restoration of atrioventricular mechanical coupling with CRT-D may improve survival regardless of LBBB status. In patients with non-LBBB, a benefit from CRT-D may occur with prolonged PR intervals. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Detection of tissue coagulation by decorrelation of ultrasonic echo signals in cavitation-enhanced high-intensity focused ultrasound treatment.

PubMed

Yoshizawa, Shin; Matsuura, Keiko; Takagi, Ryo; Yamamoto, Mariko; Umemura, Shin-Ichiro

2016-01-01

A noninvasive technique to monitor thermal lesion formation is necessary to ensure the accuracy and safety of high-intensity focused ultrasound (HIFU) treatment. The purpose of this study is to ultrasonically detect the tissue change due to thermal coagulation in the HIFU treatment enhanced by cavitation microbubbles. An ultrasound imaging probe transmitted plane waves at a center frequency of 4.5 MHz. Ultrasonic radio-frequency (RF) echo signals during HIFU exposure at a frequency of 1.2 MHz were acquired. Cross-correlation coefficients were calculated between in-phase and quadrature (IQ) data of two B-mode images with an interval time of 50 and 500 ms for the estimation of the region of cavitation and coagulation, respectively. Pathological examination of the coagulated tissue was also performed to compare with the corresponding ultrasonically detected coagulation region. The distribution of minimum hold cross-correlation coefficient between two sets of IQ data with 50-ms intervals was compared with a pulse inversion (PI) image. The regions with low cross-correlation coefficients approximately corresponded to those with high brightness in the PI image. The regions with low cross-correlation coefficients in 500-ms intervals showed a good agreement with those with significant change in histology. The results show that the regions of coagulation and cavitation could be ultrasonically detected as those with low cross-correlation coefficients between RF frames with certain intervals. This method will contribute to improve the safety and accuracy of the HIFU treatment enhanced by cavitation microbubbles.

Spike Train Similarity Space (SSIMS) Method Detects Effects of Obstacle Proximity and Experience on Temporal Patterning of Bat Biosonar

PubMed Central

Accomando, Alyssa W.; Vargas-Irwin, Carlos E.; Simmons, James A.

2018-01-01

Bats emit biosonar pulses in complex temporal patterns that change to accommodate dynamic surroundings. Efforts to quantify these patterns have included analyses of inter-pulse intervals, sonar sound groups, and changes in individual signal parameters such as duration or frequency. Here, the similarity in temporal structure between trains of biosonar pulses is assessed. The spike train similarity space (SSIMS) algorithm, originally designed for neural activity pattern analysis, was applied to determine which features of the environment influence temporal patterning of pulses emitted by flying big brown bats, Eptesicus fuscus. In these laboratory experiments, bats flew down a flight corridor through an obstacle array. The corridor varied in width (100, 70, or 40 cm) and shape (straight or curved). Using a relational point-process framework, SSIMS was able to discriminate between echolocation call sequences recorded from flights in each of the corridor widths. SSIMS was also able to tell the difference between pulse trains recorded during flights where corridor shape through the obstacle array matched the previous trials (fixed, or expected) as opposed to those recorded from flights with randomized corridor shape (variable, or unexpected), but only for the flight path shape in which the bats had previous training. The results show that experience influences the temporal patterns with which bats emit their echolocation calls. It is demonstrated that obstacle proximity to the bat affects call patterns more dramatically than flight path shape. PMID:29472848

Spike Train Similarity Space (SSIMS) Method Detects Effects of Obstacle Proximity and Experience on Temporal Patterning of Bat Biosonar.

PubMed

Accomando, Alyssa W; Vargas-Irwin, Carlos E; Simmons, James A

2018-01-01

Bats emit biosonar pulses in complex temporal patterns that change to accommodate dynamic surroundings. Efforts to quantify these patterns have included analyses of inter-pulse intervals, sonar sound groups, and changes in individual signal parameters such as duration or frequency. Here, the similarity in temporal structure between trains of biosonar pulses is assessed. The spike train similarity space (SSIMS) algorithm, originally designed for neural activity pattern analysis, was applied to determine which features of the environment influence temporal patterning of pulses emitted by flying big brown bats, Eptesicus fuscus . In these laboratory experiments, bats flew down a flight corridor through an obstacle array. The corridor varied in width (100, 70, or 40 cm) and shape (straight or curved). Using a relational point-process framework, SSIMS was able to discriminate between echolocation call sequences recorded from flights in each of the corridor widths. SSIMS was also able to tell the difference between pulse trains recorded during flights where corridor shape through the obstacle array matched the previous trials (fixed, or expected) as opposed to those recorded from flights with randomized corridor shape (variable, or unexpected), but only for the flight path shape in which the bats had previous training. The results show that experience influences the temporal patterns with which bats emit their echolocation calls. It is demonstrated that obstacle proximity to the bat affects call patterns more dramatically than flight path shape.

Excess close burst pairs in FRB 121102

NASA Astrophysics Data System (ADS)

Katz, J. I.

2018-05-01

The repeating FRB 121102 emitted a pair of apparently discrete bursts separated by 37 ms and another pair, 131 d later, separated by 34 ms, during observations that detected bursts at a mean rate of ˜2 × 10-4 s-1. While FRB 121102 is known to produce multipeaked bursts, here I assume that these `burst pairs' are truly separate bursts and not multicomponent single bursts, and consider the implications of that assumption. Their statistics are then non-Poissonian. Assuming that the emission comes from a narrow range of rotational phase, then the measured burst intervals constrain any possible periodic modulation underlying the highly episodic emission. If more such short intervals are measured a period may be determined or periodicity may be excluded. The excess of burst intervals much shorter than their mean recurrence time may be explained if FRB emit steady but narrow beams that execute a random walk in direction, perhaps indicating origin in a black hole's accretion disc.

Effects of bilastine on T-wave morphology and the QTc interval: a randomized, double-blind, placebo-controlled, thorough QTc study.

PubMed

Graff, Claus; Struijk, Johannes J; Kanters, Jørgen K; Andersen, Mads P; Toft, Egon; Tyl, Benoît

2012-05-01

The International Conference of Harmonisation (ICH) E14 guideline for thorough QT studies requires assessing the propensity of new non-antiarrhythmic drugs to affect cardiac repolarization. The present study investigates whether a composite ECG measure of T-wave morphology (Morphology Combination Score [MCS]) can be used together with the heart rate corrected QT interval (QTc) in a fully ICH E14-compliant thorough QT study to exclude clinically relevant repolarization effects of bilastine, a novel antihistamine. Thirty participants in this crossover study were randomly assigned to receive placebo, moxifloxacin 400 mg, bilastine at therapeutic and supratherapeutic doses (20 and 100 mg) and bilastine 20 mg co-administered with ketoconazole 400 mg. Resting ECGs recorded at 12 nominal time points before and after treatments were used to determine Fridericia corrected QTc (QTcF) and MCS from the T-wave characteristics: asymmetry, flatness and notching. There were no effects of bilastine monotherapy (20 and 100 mg) on MCS or QTcF at those study times where the bilastine plasma concentrations were highest. MCS changes for bilastine monotherapy did not exceed the normal intrasubject variance of T-wave shapes for triplicate ECG recordings. Maximum QTcF prolongation for bilastine monotherapy was 5 ms or less: 3.8 ms (90% CI 0.3, 7.3 ms) for bilastine 20 mg and 5.0 ms (90% CI 2.0, 8.0 ms) for bilastine 100 mg. There were no indications of bilastine inducing larger repolarization effects on T-wave morphology as compared with the QTcF interval, as evidenced by the similarity of z-score equivalents for placebo-corrected changes in MCS and QTcF values. This study shows that bilastine, at therapeutic and supratherapeutic dosages, does not induce any effects on T-wave morphology or QTcF. These results confirm the absence of an effect for bilastine on cardiac repolarization.

The influence of type 2 diabetes and gender on ventricular repolarization dispersion in patients with sub-clinic left ventricular diastolic dysfunction

PubMed Central

Jani, Ylber; Kamberi, Ahmet; Xhunga, Sotir; Pocesta, Bekim; Ferati, Fatmir; Lala, Dali; Zeqiri, Agim; Rexhepi, Atila

2015-01-01

Objective: To assess the influence of type 2 DM and gender, on the QT dispersion, Tpeak-Tend dispersion of ventricular repolarization, in patients with sub-clinic left ventricular diastolic dysfunction of the heart. Background: QT dispersion, that reflects spatial inhomogeneity in ventricular repolarization, Tpeak-Tend dispersion, this on the other hand reflects transmural inhomogeneity in ventricular repolarization, that is increased in an early stage of cardiomyopathy, and in patients with left ventricular diastolic dysfunction, as well. The left ventricular diastolic dysfunction, a basic characteristic of diabetic heart disease (diabetic cardiomyopathy), that developes earlier than systolic dysfunction, suggests that diastolic markers might be sensitive for early cardiac injury. It is also demonstrated that gender has complex influence on indices of myocardial repolarization abnormalities such as QT interval and QT dispersion. Material and methods: We performed an observational study including 300 diabetic patients with similar epidemiological-demographic characteristics recruited in our institution from May 2009 to July 2014, divided into two groups. Demographic and laboratory echocardiographic data were obtained, twelve lead resting electrocardiography, QT, QTc, Tpeak-Tend-intervals and dispersion, were determined manually, and were compared between various groups. For statistical analysis a t-test, X2 test, and logistic regression are used according to the type of variables. A p value <0.05 was considered statistically significant for a confidence interval of 95%. Results: QTc max. interval, QTc dispersion and Tpeak-Tend dispersion, were significantly higher in diabetic group with subclinical LV (left ventricular) diastolic dysfunction, than in diabetic group with normal left ventricular diastolic function (445.24±14.7 ms vs. 433.55±14.4 ms, P<0.000; 44.98±18.78 ms vs. 32.05±17.9 ms, P<0.000; 32.60±1.6 ms vs. 17.46±2.0 ms, P<0.02. Prolonged QTc max. interval was found in 33% of patients, indiabetic group with subclinical left ventricular diastolic dysfunction vs. 13.3% of patients in diabetic group with normal left ventricular diastolic function, (Chi-square: 16.77, P<0.0001). A prolonged QTc dispersion, was found in 40.6% of patients, in diabetic group with subclinical left ventricular diastolic dysfunction vs. 20% of patients in diabetic group with normal left ventricular diastolic function Chi-square: 14.11, P<0.0002). A prolonged dispersion of Tpeak-Tend interval was found in 24% of patients in diabetic group with subclinical left ventricular diastolic dysfunction vs. 13.3% of patients in diabetic group with normal left ventricular diastolic function (Chi-square: 12.00, P<0.005). Females in diabetic group with subclinical left ventricular diastolic dysfunction in comparison with males in diabetic group with subclinical left ventricular diastolic dysfunction, have a significantly prolonged: mean QTc max. interval (23.3% vs. 10%, Chisquare: 12.0, P<0.005), mean QTc dispersion (27.3% vs. 13.3%, Chi-square: 10.24, P<0.001), mean Tpeak-Tend interval (10% vs. 3.3%, Chi-square: 5.77, P<0.01), mean Tpek-Tend dispersion (16.6% vs. 6.6%, Chi-square: 8.39, P<0.003). Conclusion: The present study has shown that influences of type 2 diabetes and gender in diabetics with sub-clinical left-ventricular diastolic dysfunction are reflected in a set of electrophysiological parameters that indicate a prolonged and more heterogeneous repolarization than in diabetic patients with normal diastolic function. In addition, it demonstrates that there exist differences between diabetic females with sub-clinic LV dysfunction and those with diabetes and normal LV function in the prevalence of increased set of electrophysiological parameters that indicate a prolonged and more heterogeneous repolarization. PMID:26550530

The influence of type 2 diabetes and gender on ventricular repolarization dispersion in patients with sub-clinic left ventricular diastolic dysfunction.

PubMed

Jani, Ylber; Kamberi, Ahmet; Xhunga, Sotir; Pocesta, Bekim; Ferati, Fatmir; Lala, Dali; Zeqiri, Agim; Rexhepi, Atila

2015-01-01

To assess the influence of type 2 DM and gender, on the QT dispersion, Tpeak-Tend dispersion of ventricular repolarization, in patients with sub-clinic left ventricular diastolic dysfunction of the heart. QT dispersion, that reflects spatial inhomogeneity in ventricular repolarization, Tpeak-Tend dispersion, this on the other hand reflects transmural inhomogeneity in ventricular repolarization, that is increased in an early stage of cardiomyopathy, and in patients with left ventricular diastolic dysfunction, as well. The left ventricular diastolic dysfunction, a basic characteristic of diabetic heart disease (diabetic cardiomyopathy), that developes earlier than systolic dysfunction, suggests that diastolic markers might be sensitive for early cardiac injury. It is also demonstrated that gender has complex influence on indices of myocardial repolarization abnormalities such as QT interval and QT dispersion. We performed an observational study including 300 diabetic patients with similar epidemiological-demographic characteristics recruited in our institution from May 2009 to July 2014, divided into two groups. Demographic and laboratory echocardiographic data were obtained, twelve lead resting electrocardiography, QT, QTc, Tpeak-Tend-intervals and dispersion, were determined manually, and were compared between various groups. For statistical analysis a t-test, X(2) test, and logistic regression are used according to the type of variables. A p value <0.05 was considered statistically significant for a confidence interval of 95%. QTc max. interval, QTc dispersion and Tpeak-Tend dispersion, were significantly higher in diabetic group with subclinical LV (left ventricular) diastolic dysfunction, than in diabetic group with normal left ventricular diastolic function (445.24±14.7 ms vs. 433.55±14.4 ms, P<0.000; 44.98±18.78 ms vs. 32.05±17.9 ms, P<0.000; 32.60±1.6 ms vs. 17.46±2.0 ms, P<0.02. Prolonged QTc max. interval was found in 33% of patients, indiabetic group with subclinical left ventricular diastolic dysfunction vs. 13.3% of patients in diabetic group with normal left ventricular diastolic function, (Chi-square: 16.77, P<0.0001). A prolonged QTc dispersion, was found in 40.6% of patients, in diabetic group with subclinical left ventricular diastolic dysfunction vs. 20% of patients in diabetic group with normal left ventricular diastolic function Chi-square: 14.11, P<0.0002). A prolonged dispersion of Tpeak-Tend interval was found in 24% of patients in diabetic group with subclinical left ventricular diastolic dysfunction vs. 13.3% of patients in diabetic group with normal left ventricular diastolic function (Chi-square: 12.00, P<0.005). Females in diabetic group with subclinical left ventricular diastolic dysfunction in comparison with males in diabetic group with subclinical left ventricular diastolic dysfunction, have a significantly prolonged: mean QTc max. interval (23.3% vs. 10%, Chisquare: 12.0, P<0.005), mean QTc dispersion (27.3% vs. 13.3%, Chi-square: 10.24, P<0.001), mean Tpeak-Tend interval (10% vs. 3.3%, Chi-square: 5.77, P<0.01), mean Tpek-Tend dispersion (16.6% vs. 6.6%, Chi-square: 8.39, P<0.003). The present study has shown that influences of type 2 diabetes and gender in diabetics with sub-clinical left-ventricular diastolic dysfunction are reflected in a set of electrophysiological parameters that indicate a prolonged and more heterogeneous repolarization than in diabetic patients with normal diastolic function. In addition, it demonstrates that there exist differences between diabetic females with sub-clinic LV dysfunction and those with diabetes and normal LV function in the prevalence of increased set of electrophysiological parameters that indicate a prolonged and more heterogeneous repolarization.

Generation of double pulses at the Shanghai soft X-ray free electron laser facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhen; Feng, Chao; Gu, Qiang

2017-01-28

In this paper, we present the promise of a new method generating double electron pulses with the picosecond-scale pulse length and the tunable interpulse spacing at several picoseconds, which has been witnessed an impressive potential of application in pump-probe techniques, two-color X-ray free electron laser (FEL), high-gradient witness bunch acceleration in a plasma, etc. Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in the linear accelerator. Some comparisons have been made between the new method and the existing ways as well.

Temporal prediction restores the evaluative processing of delayed action feedback: an electrophysiological study.

PubMed

Kimura, Kenta; Kimura, Motohiro

2016-09-28

The evaluative processing of the valence of action feedback is reflected by an event-related brain potential component called feedback-related negativity (FRN) or reward positivity (RewP). Recent studies have shown that FRN/RewP is markedly reduced when the action-feedback interval is long (e.g. 6000 ms), indicating that an increase in the action-feedback interval can undermine the evaluative processing of the valence of action feedback. The aim of the present study was to investigate whether or not such undermined evaluative processing of delayed action feedback could be restored by improving the accuracy of the prediction in terms of the timing of action feedback. With a typical gambling task in which the participant chose one of two cards and received an action feedback indicating monetary gain or loss, the present study showed that FRN/RewP was significantly elicited even when the action-feedback interval was 6000 ms, when an auditory stimulus sequence was additionally presented during the action-feedback interval as a temporal cue. This result suggests that the undermined evaluative processing of delayed action feedback can be restored by increasing the accuracy of the prediction on the timing of the action feedback.

Benthic foraminiferal paleoecology and depositional patterns during the Albian at DSDP Site 327 (Falkland Plateau)

NASA Astrophysics Data System (ADS)

Lopes, Fernando M.; Koutsoukos, Eduardo A. M.; Kochhann, Karlos G. D.; Savian, Jairo F.; Fauth, Gerson

2017-10-01

The present paleoenvironmental study uses a spectrum of analytical methods, such as benthic foraminiferal assemblages, total organic carbon (TOC), calcium carbonate (CaCO3) contents and magnetic susceptibility (MS), to monitor variations in primary productivity, bottom-water oxygenation and depositional patterns within the Albian interval recovered at DSDP Site 327, Hole A, Falkland Plateau. Thirty-three benthic foraminiferal species were identified in the studied section and, based on the abundances of morphogroups (epifaunal and shallow infaunal), two distinct associations were identified. Stratigraphic intervals dominated by the epifaunal morphogroup can be interpreted as indicative of bottom-waters with low-oxygen content. However, these decreases in oxygenation were not vigorous enough to establish a dominance of deep-infaunal morphotypes, as supported by the low TOC values. Intervals dominated by the shallow infaunal morphogroup were interpreted as subjected to moderate to high nutrient flux to the ocean floor. These intervals are associated with high MS values and low CaCO3 content, suggesting that dissolution processes, rather than increased primary productivity, controlled CaCO3 accumulation in the studied section. Furthermore, faunal analysis points to deposition in an outer neritic to upper bathyal paleoenvironment.

Timing matters: the processing of pitch relations

PubMed Central

Weise, Annekathrin; Grimm, Sabine; Trujillo-Barreto, Nelson J.; Schröger, Erich

2014-01-01

The human central auditory system can automatically extract abstract regularities from a variant auditory input. To this end, temporarily separated events need to be related. This study tested whether the timing between events, falling either within or outside the temporal window of integration (~350 ms), impacts the extraction of abstract feature relations. We utilized tone pairs for which tones within but not across pairs revealed a constant pitch relation (e.g., pitch of second tone of a pair higher than pitch of first tone, while absolute pitch values varied across pairs). We measured the mismatch negativity (MMN; the brain’s error signal to auditory regularity violations) to second tones that rarely violated the pitch relation (e.g., pitch of second tone lower). A Short condition in which tone duration (90 ms) and stimulus onset asynchrony between the tones of a pair were short (110 ms) was compared to two conditions, where this onset asynchrony was long (510 ms). In the Long Gap condition, the tone durations were identical to Short (90 ms), but the silent interval was prolonged by 400 ms. In Long Tone, the duration of the first tone was prolonged by 400 ms, while the silent interval was comparable to Short (20 ms). Results show a frontocentral MMN of comparable amplitude in all conditions. Thus, abstract pitch relations can be extracted even when the within-pair timing exceeds the integration period. Source analyses indicate MMN generators in the supratemporal cortex. Interestingly, they were located more anterior in Long Gap than in Short and Long Tone. Moreover, frontal generator activity was found for Long Gap and Long Tone. Thus, the way in which the system automatically registers irregular abstract pitch relations depends on the timing of the events to be linked. Pending that the current MMN data mirror established abstract rule representations coding the regular pitch relation, neural processes building these templates vary with timing. PMID:24966823

Comparison of yoga and walking-exercise on cardiac time intervals as a measure of cardiac function in elderly with increased pulse pressure.

PubMed

Patil, Satish Gurunathrao; Patil, Shankargouda S; Aithala, Manjunatha R; Das, Kusal Kanti

Arterial aging along with increased blood pressure(BP) has become the major cardiovascular(CV) risk in elderly. The aim of the study was to compare the effects of yoga program and walking-exercise on cardiac function in elderly with increased pulse pressure (PP). An open label, parallel-group randomized controlled study design was adopted. Elderly individuals aged ≥60 years with PP≥60mmHg were recruited for the study. Yoga (study) group (n=30) was assigned for yoga training and walking (exercise) group (n=30) for walking with loosening practices for one hour in the morning for 6days in a week for 3 months. The outcome measures were cardiac time intervals derived from pulse wave analysis and ECG: resting heart rate (RHR), diastolic time(DT), ventricular ejection time(LVET), upstroke time(UT), ejection duration index (ED%), pre-ejection period (PEP), rate pressure product (RPP) and percentage of mean arterial pressure (%MAP). The mean within-yoga group change in RHR(bpm) was 4.41 (p=0.031), PD(ms): -50.29 (p=0.042), DT(ms): -49.04 (p=0.017), ED%: 2.107 (p=0.001), ES(mmHg/ms): 14.62 (p=0.118), ET(ms): -0.66 (p=0.903), UT(ms): -2.54 (p=0.676), PEP(ms): -1.25 (p=0.11) and %MAP: 2.08 (p=0.04). The mean within-control group change in HR (bpm) was 0.35 (p=0.887), PD (ms): 11.15(p=0.717), DT (ms): 11.3 (p=0.706), ED%: -0.101 (p=0.936), ES (mmHg/ms): 0.75 (p=0.926), ET(ms): 2.2 (p=0.721), UT(ms):4.7(p=455), PEP (ms): 2.1(p=0.11), %MAP: 0.65 (p=0.451). A significant difference between-group was found in RHR (p=0.036), PD (p=0.02), ED% (p=0.049), LVET (p=0.048), DT (p=0.02) and RPP (p=0.001). Yoga practice for 3 months showed a significant improvement in diastolic function with a minimal change in systolic function. Yoga is more effective than walking in improving cardiac function in elderly with high PP. Copyright © 2017 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

Evidence for a neural signature of musical preference during silence.

PubMed

Joucla, Coralie; Nicolier, Magali; Giustiniani, Julie; Brunotte, Gaelle; Noiret, Nicolas; Monnin, Julie; Magnin, Eloi; Pazart, Lionel; Moulin, Thierry; Haffen, Emmanuel; Vandel, Pierre; Gabriel, Damien

2018-03-01

One of the most basic and person-specific affective responses to music is liking. The present investigation sought to determine whether liking was preserved during spontaneous auditory imagery. To this purpose, we inserted two-second silent intervals into liked and disliked songs, a method known to automatically recreate a mental image of these songs. Neural correlates of musical preference were measured by high-density electroencephalography in twenty subjects who had to listen to a set of five pre-selected unknown songs the same number of times for two weeks. Time frequency analysis of the two most liked and the two most disliked songs confirmed the presence of neural responses related to liking. At the beginning of silent intervals (400-900 ms and 1000-1300 ms), significant differences in theta activity were originating from the inferior frontal and superior temporal gyrus. These two brain structures are known to work together to process various aspects of music and are also activated when measuring liking while listening to music. At the end of silent intervals (1400-1900 ms), significant alpha activity differences originating from the insula were observed, whose exact role remains to be explored. Although exposure was controlled for liked and disliked songs, liked songs were rated as more familiar, underlying the strong relationship that exists between liking, exposure, and familiarity. Copyright © 2018 Elsevier B.V. All rights reserved.

Cardiovascular effects of fenoterol under conditions of hypoxaemia.

PubMed Central

Bremner, P; Burgess, C D; Crane, J; McHaffie, D; Galletly, D; Pearce, N; Woodman, K; Beasley, R

1992-01-01

BACKGROUND: The reason for the association of increased risk of death with fenoterol in patients with asthma in New Zealand is unknown but may relate to its cardiovascular effects. Most deaths from asthma occur outside hospital, where hypoxaemia is likely to be a complicating factor. The cardiovascular effects of fenoterol have been investigated therefore under conditions of normoxaemia and hypoxaemia. METHOD: Eight healthy men were studied on two occasions. Measurements of heart rate, blood pressure, total electromechanical systole (QS2I), electrocardiographic QTc interval, cardiac index, stroke volume, and ejection fraction were made under conditions of normoxaemia and hypoxaemia (arterial oxygen saturation 90%) before and after administration of 800 micrograms of fenoterol by a metered dose inhaler. The order in which treatments were applied was according to a Latin square design. RESULTS: Before inhalation of fenoterol hypoxaemia was associated with a significant increase in heart rate (8 beats/min) and QTc interval (15.6 ms). Under conditions of normoxaemia fenoterol caused a significant increase in heart rate (14.3 beats/min), systolic blood pressure (7.7 mm Hg), stroke volume (27.7 ml), cardiac index (1.6 1/min/m2), ejection fraction (11.48), and QTc interval (32.9 ms) and a fall in QS2I (-23.2 ms) and diastolic blood pressure (-8.4 mm Hg). Under conditions of hypoxaemia the changes after inhalation of fenoterol were similar to those recorded during normoxaemia; thus the effects of hypoxaemia and fenoterol were additive (heart rate 21.9 beats/min, QTc 43.5 ms with fenoterol and hypoxaemia). CONCLUSION: The chronotropic and electrophysiological effects of fenoterol were enhanced by conditions of hypoxaemia. PMID:1481183

Explosive Strength of the Knee Extensors: The Influence of Criterion Trial Detection Methodology on Measurement Reproducibility.

PubMed

Dirnberger, Johannes; Wiesinger, Hans-Peter; Wiemer, Nicolas; Kösters, Alexander; Müller, Erich

2016-04-01

The present study was conducted to assess test-retest reproducibility of explosive strength measurements during single-joint isometric knee extension using the IsoMed 2000 dynamometer. Thirty-one physically active male subjects (mean age: 23.7 years) were measured on two occasions separated by 48-72 h. The intraclass correlation coefficient (ICC 2,1) and the coefficient of variation (CV) were calculated for (i) maximum torque (MVC), (ii) the peak rate of torque development (RTD peak ) as well as for (iii) the average rate of torque development (RTD) and the impulse taken at several predefined time intervals (0-30 to 0-300 ms); thereby explosive strength variables were derived in two conceptually different versions: on the one hand from the MVC-trial (version I), on the other hand from the trial showing the RTD peak (version II). High ICC-values (0.80-0.99) and acceptable CV-values (1.9-8.7%) could be found for MVC as well as for the RTD and the impulse taken at time intervals of ≥100 ms, regardless of whether version I or II was used. In contrast, measurements of the RTD peak as well as the RTD and the impulse taken during the very early contraction phase (i.e. RTD/impulse 0-30ms and RTD/impulse 0-50ms ) showed clearly weaker reproducibility results (ICC: 0.53-0.84; CV: 7.3-16.4%) and gave rise to considerable doubts as to clinical usefulness, especially when derived using version I. However, if there is a need to measure explosive strength for earlier time intervals in practice, it is, in view of stronger reproducibility results, recommended to concentrate on measures derived from version II, which is based on the RTD peak -trial.

The effects of prepulse-blink reflex trial repetition and prepulse change on blink reflex modification at short and long lead intervals.

PubMed

Lipp, O V; Siddle, D A

1998-01-01

Prepulse inhibition and facilitation of the blink reflex are said to reflect different responses elicited by the lead stimulus, transient detection and orienting response respectively. Two experiments investigated the effects of trial repetition and lead stimulus change on blink modification. It was hypothesized that these manipulations will affect orienting and thus blink facilitation to a greater extent than they will affect transient detection and thus blink inhibition. In Experiment 1 (N = 64), subjects were trained with a sequence of 12 lead stimulus and 12 blink stimulus alone presentations, and 24 lead stimulus-blink stimulus pairings. Lead interval was 120 ms for 12 of the trials and 2000 ms for the other 12. For half the subjects this sequence was followed by a change in pitch of the lead stimulus. In Experiment 2 (N = 64), subjects were trained with a sequence of 36 blink alone stimuli and 36 lead stimulus-blink stimulus pairings. The lead interval was 120 ms for half the subjects and 2000 ms for the other half. The pitch of the lead stimulus on prestimulus trials 31-33 was changed for half the subjects in each group. In both experiments, the amount of blink inhibition decreased during training whereas the amount of blink facilitation remained unchanged. Lead stimulus change had no effect on blink modification in either experiment although it resulted in enhanced skin conductance responses and greater heart rate deceleration in Experiment 2. The present results are not consistent with the notion that blink facilitation is linked to orienting whereas blink inhibition reflects a transient detection mechanism.

Effect of mental challenge induced by movie clips on action potential duration in normal human subjects independent of heart rate.

PubMed

Child, Nicholas; Hanson, Ben; Bishop, Martin; Rinaldi, Christopher A; Bostock, Julian; Western, David; Cooklin, Michael; O'Neil, Mark; Wright, Matthew; Razavi, Reza; Gill, Jaswinder; Taggart, Peter

2014-06-01

Mental stress and emotion have long been associated with ventricular arrhythmias and sudden death in animal models and humans. The effect of mental challenge on ventricular action potential duration (APD) in conscious healthy humans has not been reported. Activation recovery intervals measured from unipolar electrograms as a surrogate for APD (n=19) were recorded from right and left ventricular endocardium during steady-state pacing, whilst subjects watched an emotionally charged film clip. To assess the possible modulating role of altered respiration on APD, the subjects then repeated the same breathing pattern they had during the stress, but without the movie clip. Hemodynamic parameters (mean, systolic, and diastolic blood pressure, and rate of pressure increase) and respiration rate increased during the stressful part of the film clip (P=0.001). APD decreased during the stressful parts of the film clip, for example, for global right ventricular activation recovery interval at end of film clip 193.8 ms (SD, 14) versus 198.0 ms (SD, 13) during the matched breathing control (end film left ventricle 199.8 ms [SD, 16] versus control 201.6 ms [SD, 15]; P=0.004). Respiration rate increased during the stressful part of the film clip (by 2 breaths per minute) and was well matched in the respective control period without any hemodynamic or activation recovery interval changes. Our results document for the first time direct recordings of the effect of a mental challenge protocol on ventricular APD in conscious humans. The effect of mental challenge on APD was not secondary to emotionally induced altered respiration or heart rate. © 2014 American Heart Association, Inc.

Timing of repetition suppression of event-related potentials to unattended objects.

PubMed

Stefanics, Gabor; Heinzle, Jakob; Czigler, István; Valentini, Elia; Stephan, Klaas Enno

2018-05-26

Current theories of object perception emphasize the automatic nature of perceptual inference. Repetition suppression (RS), the successive decrease of brain responses to repeated stimuli, is thought to reflect the optimization of perceptual inference through neural plasticity. While functional imaging studies revealed brain regions that show suppressed responses to the repeated presentation of an object, little is known about the intra-trial time course of repetition effects to everyday objects. Here we used event-related potentials (ERP) to task-irrelevant line-drawn objects, while participants engaged in a distractor task. We quantified changes in ERPs over repetitions using three general linear models (GLM) that modelled RS by an exponential, linear, or categorical "change detection" function in each subject. Our aim was to select the model with highest evidence and determine the within-trial time-course and scalp distribution of repetition effects using that model. Model comparison revealed the superiority of the exponential model indicating that repetition effects are observable for trials beyond the first repetition. Model parameter estimates revealed a sequence of RS effects in three time windows (86-140ms, 322-360ms, and 400-446ms) and with occipital, temporo-parietal, and fronto-temporal distribution, respectively. An interval of repetition enhancement (RE) was also observed (320-340ms) over occipito-temporal sensors. Our results show that automatic processing of task-irrelevant objects involves multiple intervals of RS with distinct scalp topographies. These sequential intervals of RS and RE might reflect the short-term plasticity required for optimization of perceptual inference and the associated changes in prediction errors (PE) and predictions, respectively, over stimulus repetitions during automatic object processing. This article is protected by copyright. All rights reserved. © 2018 The Authors European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

The Relationship between MOC Reflex and Masked Threshold

PubMed Central

Garinis, Angela; Werner, Lynne; Abdala, Carolina

2011-01-01

Otoacoustic emission (OAE) amplitude can be reduced by acoustic stimulation. This effect is produced by the medial olivocochlear (MOC) reflex. Past studies have shown that the MOC reflex is related to listening in noise and attention. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold was investigated in 19 adults. Detection thresholds were determined for a 1000-Hz, 300-ms tone presented simultaneously with one repetition of a 300-ms masker in an ongoing train of 300-ms masker bursts at 600-ms intervals. Three masking conditions were tested: 1) broadband noise 2) a fixed-frequency 4-tone complex masker and 3) a random-frequency 4-tone complex masker. Broadband noise was expected to produce energetic masking and the tonal maskers were expected to produce informational masking in some listeners. DPOAEs were recorded at fine frequency interval from 500 to 4000 Hz, with and without contralateral acoustic stimulation. MOC reflex strength was estimated as a reduction in baseline level and a shift in frequency of DPOAE fine-structure maxima near 1000-Hz. MOC reflex and psychophysical testing were completed in separate sessions. Individuals with poorer thresholds in broadband noise and in random-frequency maskers were found to have stronger MOC reflexes. PMID:21878379

The relative contributions of processing speed and cognitive load to working memory accuracy in multiple sclerosis.

PubMed

Leavitt, Victoria M; Lengenfelder, Jean; Moore, Nancy B; Chiaravalloti, Nancy D; DeLuca, John

2011-06-01

Cognitive symptoms of multiple sclerosis (MS) include processing-speed deficits and working memory impairment. The precise manner in which these deficits interact in individuals with MS remains to be explicated. We hypothesized that providing more time on a complex working memory task would result in performance benefits for individuals with MS relative to healthy controls. Fifty-three individuals with clinically definite MS and 36 matched healthy controls performed a computerized task that systematically manipulated cognitive load. The interval between stimuli presentations was manipulated to provide increasing processing time. The results confirmed that individuals with MS who have processing-speed deficits significantly improve in performance accuracy when given additional time to process the information in working memory. Implications of these findings for developing appropriate cognitive rehabilitation interventions are discussed.

Reverse causality behind the association between reproductive history and MS.

PubMed

Hedström, A K; Hillert, J; Olsson, T; Alfredsson, L

2014-04-01

Possible associations between childbearing patterns and multiple sclerosis (MS) risk have been studied for a long time, with conflicting results. We aimed to investigate the influence of reproductive history on MS risk. Using a Swedish population-based case-control study involving incident cases of MS (1798 cases, 3907 controls), we calculated odds ratios (OR) for MS comparing parents with childless subjects together with 95% confidence intervals (CI) employing logistic regression. Overall, there was an association between having children and reduced MS risk among both sexes. Subjects who had become parents within five years prior to the index year had a substantially reduced risk of developing MS (OR 0.6, 95% CI 0.5-0.8 for women, and OR 0.4, 95% CI 0.3-0.6 for men). No association between having children and MS risk was observed when more than 10 years had passed since the birth of the last child. We found no association between increasing offspring number and MS risk. The observed association between reproductive history and MS risk is restricted to a limited time period preceding the index year, with similar findings in both sexes, which contradicts biologic impact of pregnancy on MS risk and argues in favor of reverse causality, i.e. that fecundity is affected by yet-undiagnosed MS.

A novel predictive pharmacokinetic/pharmacodynamic model of repolarization prolongation derived from the effects of terfenadine, cisapride and E-4031 in the conscious chronic av node--ablated, His bundle-paced dog.

PubMed

Nolan, Emily R; Feng, Meihua Rose; Koup, Jeffrey R; Liu, Jing; Turluck, Daniel; Zhang, Yiqun; Paulissen, Jerome B; Olivier, N Bari; Miller, Teresa; Bailie, Marc B

2006-01-01

Terfenadine, cisapride, and E-4031, three drugs that prolong ventricular repolarization, were selected to evaluate the sensitivity of the conscious chronic atrioventricular node--ablated, His bundle-paced Dog for defining drug induced cardiac repolarization prolongation. A novel predictive pharmacokinetic/pharmacodynamic model of repolarization prolongation was generated from these data. Three male beagle dogs underwent radiofrequency AV nodal ablation, and placement of a His bundle-pacing lead and programmable pacemaker under anesthesia. Each dog was restrained in a sling for a series of increasing dose infusions of each drug while maintained at a constant heart rate of 80 beats/min. RT interval, a surrogate for QT interval in His bundle-paced dogs, was recorded throughout the experiment. E-4031 induced a statistically significant RT prolongation at the highest three doses. Cisapride resulted in a dose-dependent increase in RT interval, which was statistically significant at the two highest doses. Terfenadine induced a dose-dependent RT interval prolongation with a statistically significant change occurring only at the highest dose. The relationship between drug concentration and RT interval change was described by a sigmoid E(max) model with an effect site. Maximum RT change (E(max)), free drug concentration at half of the maximum effect (EC(50)), and free drug concentration associated with a 10 ms RT prolongation (EC(10 ms)) were estimated. A linear correlation between EC(10 ms) and HERG IC(50) values was identified. The conscious dog with His bundle-pacing detects delayed cardiac repolarization related to I(Kr) inhibition, and detects repolarization change induced by drugs with activity at multiple ion channels. A clinically relevant sensitivity and a linear correlation with in vitro HERG data make the conscious His bundle-paced dog a valuable tool for detecting repolarization effect of new chemical entities.

Atrial Premature Depolarization-Induced Changes in QRS and T Wave Morphology on Resting Electrocardiograms in Horses.

PubMed

Broux, B; De Clercq, D; Decloedt, A; Van Der Vekens, N; Verheyen, T; Ven, S; Pardon, B; van Loon, G

2016-07-01

The electrocardiographic differentiation between atrial (APDs) and ventricular (VPDs) premature depolarizations is important. P wave prematurity and normal QRS and T wave morphology generally are used as discriminating criteria for APDs. The aim of this study was to determine whether P, Q, R, S, and T wave amplitude, PQ interval, QRS and P wave duration and P and T wave morphology differ between APDs and sinus beats. To determine the relationship between the RR coupling interval and the change in S wave amplitude between sinus beats and APDs. Case-control study. From a modified base-apex configuration of 30 horses with APDs at rest, sinus beat and APD associated preceding RR interval, P, PQ and QRS duration and P, R, S, and T wave amplitudes were measured. Linear mixed models and logistic regression were used to determine the effect of APDs on the ECG variables studied. In comparison to sinus beats, APDs were associated with a significant (P < .001) change in P amplitude (-0.03 ± 0.01 mV) and increase in S (0.20 ± 0.02 mV) and T (0.08 ± 0.03 mV) amplitude. PQ (-20.3 ± 5.2 ms) and RR (-519 ± 14 ms) interval and P duration (-21.1 ± 3.0 ms) decreased (P < .001). APDs were significantly associated with a singular positive P wave (OR: 11.0, P < .001) and were more likely to have a monophasic positive T wave (OR: 9.2, P < .001). A smaller RR coupling interval was associated with an increased relative difference in S amplitude (P < .01). Atrial premature depolarizations may lead to changes in QRS and T wave morphology. Knowledge of these changes is important to avoid interpreting certain APDs as VPDs. Copyright © 2016 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

"J waves" induced after short coupling intervals: a manifestations of latent depolarization abnormality?

PubMed

Aizawa, Yoshifusa; Nakayama, Masafumi; Sato, Masahito; Okabe, Masaaki; Aizawa, Yoshiyasu; Takatsuki, Seiji; Fukuda, Keiichi

2017-04-24

To confirm the presence of tachycardia-induced slur or notch in the terminal portion of the QRS complexes in a general patient population. A tachycardia-induced J wave was defined as a slur or notch in the terminal portion of the QRS complexes newly induced at short RR intervals during atrial premature contractions (APCs) or atrial electrical stimulation in the electrophysiological study (EPS). Twenty-three out of 2000 patients with general diseases were involved. All patients with aborted sudden cardiac death, ventricular fibrillation or a family history of sudden cardiac death were excluded. The mean age was 72 ± 9 years, and 11 patients were male (47.8%). When the RR interval was shortened from 821 ± 142 ms to 464 ± 52 ms in the conducted APCs (P < 0.0001), J waves became diagnostic (0.02 ± 0.03 mV to 0.20 ± 0.07 mV, P < 0.0001). J waves were confined to the inferior leads in 22 (95.7%) patients and were notched in 11 (47.8%) and slurred in 12 (52.2%) patients. The induction of J waves was accompanied by visible changes of the QRS morphology. When the post-APC RR interval was prolonged to 992 ± 305 ms (P = 0.0154 vs. baseline), the J waves were similar to baseline levels. During the EPS, J wave induction was confirmed during atrial stimulation. There were no characteristic clinical or ECG features in the patients with tachycardia-induced J waves. J waves can be newly induced by short RR intervals in a general patient population, and a conduction delay is the likely mechanism causing such J waves. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For Permissions, please email: journals.permissions@oup.com.

Adaptation to visual or auditory time intervals modulates the perception of visual apparent motion

PubMed Central

Zhang, Huihui; Chen, Lihan; Zhou, Xiaolin

2012-01-01

It is debated whether sub-second timing is subserved by a centralized mechanism or by the intrinsic properties of task-related neural activity in specific modalities (Ivry and Schlerf, 2008). By using a temporal adaptation task, we investigated whether adapting to different time intervals conveyed through stimuli in different modalities (i.e., frames of a visual Ternus display, visual blinking discs, or auditory beeps) would affect the subsequent implicit perception of visual timing, i.e., inter-stimulus interval (ISI) between two frames in a Ternus display. The Ternus display can induce two percepts of apparent motion (AM), depending on the ISI between the two frames: “element motion” for short ISIs, in which the endmost disc is seen as moving back and forth while the middle disc at the overlapping or central position remains stationary; “group motion” for longer ISIs, in which both discs appear to move in a manner of lateral displacement as a whole. In Experiment 1, participants adapted to either the typical “element motion” (ISI = 50 ms) or the typical “group motion” (ISI = 200 ms). In Experiments 2 and 3, participants adapted to a time interval of 50 or 200 ms through observing a series of two paired blinking discs at the center of the screen (Experiment 2) or hearing a sequence of two paired beeps (with pitch 1000 Hz). In Experiment 4, participants adapted to sequences of paired beeps with either low pitches (500 Hz) or high pitches (5000 Hz). After adaptation in each trial, participants were presented with a Ternus probe in which the ISI between the two frames was equal to the transitional threshold of the two types of motions, as determined by a pretest. Results showed that adapting to the short time interval in all the situations led to more reports of “group motion” in the subsequent Ternus probes; adapting to the long time interval, however, caused no aftereffect for visual adaptation but significantly more reports of group motion for auditory adaptation. These findings, suggesting amodal representation for sub-second timing across modalities, are interpreted in the framework of temporal pacemaker model. PMID:23133408

Effect of PR interval prolongation on long-term outcomes in patients with left bundle branch block vs non-left bundle branch block morphologies undergoing cardiac resynchronization therapy.

PubMed

Rickard, John; Karim, Mohammad; Baranowski, Bryan; Cantillon, Daniel; Spragg, David; Tang, W H Wilson; Niebauer, Mark; Grimm, Richard; Trulock, Kevin; Wilkoff, Bruce; Varma, Niraj

2017-10-01

Although the influence of QRS duration (QRSd) and/or bundle branch block morphology on outcomes of cardiac resynchronization therapy (CRT) have been well studied, the effect of PR interval remains uncertain. The purpose of this study was to evaluate the impact of PR prolongation (PRp) before CRT on long-term outcomes, specifically taking into account bundle branch block morphology and QRSd. We extracted clinical data on consecutive patients undergoing CRT. Multivariate models were constructed to analyze the effect of PRp (≥200 ms) on the combined endpoint of death, heart transplant, or left ventricular assist device. Kaplan-Meier curves were constructed stratifying patients based on bundle branch block and QRSd (dichotomized by 150 ms). Of the 472 patients who met inclusion criteria, 197 (41.7%) had PR interval ≥200 ms. During follow-up (mean 5.1 ± 2.6 years) there were 214 endpoints, of which 109 (23.1%) occurred in patients with PRp. In multivariate analysis, PRp was independently associated with worsened outcomes (hazard ratio 1.34, 95% confidence interval 1.01-1.77, P = .04). When stratified by bundle branch block morphology, PRp was significantly associated with worsened outcomes (log-rank P <.001) in patients with LBBB but not in those with non-LBBB (log-rank P = .55). Among patients with LBBB, stratified by QRSd, patients without PRp had improved outcomes compared to those with PRp independent of QRSd (log-rank P <.001). PRp is an independent predictor of impaired long-term outcome after CRT among patients with LBBB but not in non-LBBB patients. Notably, among LBBB patients, PRp is a more important predictor than QRSd in assessing long-term outcomes. Copyright © 2017. Published by Elsevier Inc.

A thorough QT study to evaluate the effects of therapeutic and supratherapeutic doses of delafloxacin on cardiac repolarization.

PubMed

Litwin, Jeffrey S; Benedict, Michael S; Thorn, Michael D; Lawrence, Laura E; Cammarata, Sue K; Sun, Eugene

2015-01-01

A randomized, double-blind, placebo-controlled, 4-period crossover study was conducted in 52 healthy adults to assess the effect of delafloxacin on the corrected QT (QTc) interval. The QT interval, corrected for heart rate using Fridericia's formula (QTcF), was determined predose and at 0.5, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 12, 18, and 24 h after dosing with delafloxacin at 300 mg intravenously (i.v.; therapeutic), delafloxacin at 900 mg i.v. (supratherapeutic), moxifloxacin at 400 mg orally (p.o.; positive control), and placebo. The pharmacokinetic profile of delafloxacin was also evaluated. At each time point after delafloxacin administration, the upper limit of the 90% confidence interval (CI) for the placebo-corrected change from the predose baseline in QTcF (ΔΔQTcF) was less than 10 ms (maximum, 3.9 ms at 18 h after dosing), indicating an absence of a clinically meaningful increase in the QTc interval. The lower limit of the 90% CI of ΔΔQTcF for moxifloxacin versus placebo was longer than 5 ms at all 5 time points selected for assay sensitivity analysis, demonstrating that the study was adequately sensitive to assess QTc prolongation. There was no positive relationship between delafloxacin plasma concentrations and ΔΔQTcF. Treatment-emergent adverse events (AEs) were more frequent among subjects receiving a single supratherapeutic dose of 900 mg delafloxacin. There were no deaths, serious AEs, or AEs leading to study discontinuation and no clinically meaningful abnormalities in laboratory values or vital signs observed at any time point after any dose of the study drug. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Automated Algorithm for J-Tpeak and Tpeak-Tend Assessment of Drug-Induced Proarrhythmia Risk

DOE PAGES

Johannesen, Lars; Vicente, Jose; Hosseini, Meisam; ...

2016-12-30

Prolongation of the heart rate corrected QT (QTc) interval is a sensitive marker of torsade de pointes risk; however it is not specific as QTc prolonging drugs that block inward currents are often not associated with torsade. Recent work demonstrated that separate analysis of the heart rate corrected J-T peakc (J-T peakc) and T peak-T end intervals can identify QTc prolonging drugs with inward current block and is being proposed as a part of a new cardiac safety paradigm for new drugs (the “CiPA” initiative). In this work, we describe an automated measurement methodology for assessment of the J-T peakcmore » and T peak-T end intervals using the vector magnitude lead. The automated measurement methodology was developed using data from one clinical trial and was evaluated using independent data from a second clinical trial. Comparison between the automated and the prior semi-automated measurements shows that the automated algorithm reproduces the semi-automated measurements with a mean difference of single-deltas <1 ms and no difference in intra-time point variability (p for all > 0.39). In addition, the time-profile of the baseline and placebo-adjusted changes are within 1 ms for 63% of the time-points (86% within 2 ms). Importantly, the automated results lead to the same conclusions about the electrophysiological mechanisms of the studied drugs. We have developed an automated algorithm for assessment of J-T peakc and T peak-T end intervals that can be applied in clinical drug trials. Under the CiPA initiative this ECG assessment would determine if there are unexpected ion channel effects in humans compared to preclinical studies. In conclusion, the algorithm is being released as open-source software.« less

Automated Algorithm for J-Tpeak and Tpeak-Tend Assessment of Drug-Induced Proarrhythmia Risk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johannesen, Lars; Vicente, Jose; Hosseini, Meisam

Prolongation of the heart rate corrected QT (QTc) interval is a sensitive marker of torsade de pointes risk; however it is not specific as QTc prolonging drugs that block inward currents are often not associated with torsade. Recent work demonstrated that separate analysis of the heart rate corrected J-T peakc (J-T peakc) and T peak-T end intervals can identify QTc prolonging drugs with inward current block and is being proposed as a part of a new cardiac safety paradigm for new drugs (the “CiPA” initiative). In this work, we describe an automated measurement methodology for assessment of the J-T peakcmore » and T peak-T end intervals using the vector magnitude lead. The automated measurement methodology was developed using data from one clinical trial and was evaluated using independent data from a second clinical trial. Comparison between the automated and the prior semi-automated measurements shows that the automated algorithm reproduces the semi-automated measurements with a mean difference of single-deltas <1 ms and no difference in intra-time point variability (p for all > 0.39). In addition, the time-profile of the baseline and placebo-adjusted changes are within 1 ms for 63% of the time-points (86% within 2 ms). Importantly, the automated results lead to the same conclusions about the electrophysiological mechanisms of the studied drugs. We have developed an automated algorithm for assessment of J-T peakc and T peak-T end intervals that can be applied in clinical drug trials. Under the CiPA initiative this ECG assessment would determine if there are unexpected ion channel effects in humans compared to preclinical studies. In conclusion, the algorithm is being released as open-source software.« less

A thorough QT study to evaluate the QTc prolongation potential of two neuropsychiatric drugs, quetiapine and escitalopram, in healthy volunteers.

PubMed

Kim, Anhye; Lim, Kyoung Soo; Lee, Howard; Chung, Hyewon; Yoon, Seo Hyun; Yu, Kyung-Sang; Cho, Joo-Youn; Jang, In-Jin; Chung, Jae-Yong

2016-07-01

Prolongation of the QT interval on an ECG is a surrogate marker for predicting the proarrhythmic potential of a drug under development. The aim of this study was to evaluate the QTc prolongation potential of two neuropsychiatric drugs, quetiapine immediate release (IR) and escitalopram, in healthy individuals. This was a randomized, open-label, 4×4 Williams crossover study, with four single-dose treatments [placebo, 400 mg moxifloxacin (positive control), 20 mg escitalopram, and 100 mg quetiapine IR], conducted in 40 healthy volunteers. Serial blood samples for pharmacokinetics and ECG were collected. Individually, RR-corrected QTc intervals (QTcI) and placebo-adjusted changes from baseline values of QTcI (ΔΔQTcI) were evaluated. Lower-bound values of the one-sided 95% confidence interval for ΔΔQTcI of moxifloxacin with more than 5 ms confirmed the sensitivity of the assay. The maximum upper bound 95% confidence interval for the ΔΔQTcI of quetiapine IR and escitalopram was 13.7 and 10.5 ms, with mean estimates of 10.2 and 6.9 ms, respectively. Peak effects of moxifloxacin and quetiapine IR on ΔΔQTcI were observed at approximately time to maximum concentration (Tmax), whereas that of escitalopram was observed 3 h after Tmax. The concentration-ΔΔQTcI relationships of quetiapine IR and escitalopram were relatively flat, as compared with that of moxifloxacin. The results demonstrated the validity of trial methodology and that quetiapine IR and escitalopram caused QT prolongation in healthy individuals. In addition, hysteresis of escitalopram-induced QTc prolongation. These results indicate that higher doses of these drugs could lead to greater QT prolongation in a dose-response manner.

A Thorough QT Study To Evaluate the Effects of Therapeutic and Supratherapeutic Doses of Delafloxacin on Cardiac Repolarization

PubMed Central

Benedict, Michael S.; Thorn, Michael D.; Lawrence, Laura E.; Cammarata, Sue K.; Sun, Eugene

2015-01-01

A randomized, double-blind, placebo-controlled, 4-period crossover study was conducted in 52 healthy adults to assess the effect of delafloxacin on the corrected QT (QTc) interval. The QT interval, corrected for heart rate using Fridericia's formula (QTcF), was determined predose and at 0.5, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 12, 18, and 24 h after dosing with delafloxacin at 300 mg intravenously (i.v.; therapeutic), delafloxacin at 900 mg i.v. (supratherapeutic), moxifloxacin at 400 mg orally (p.o.; positive control), and placebo. The pharmacokinetic profile of delafloxacin was also evaluated. At each time point after delafloxacin administration, the upper limit of the 90% confidence interval (CI) for the placebo-corrected change from the predose baseline in QTcF (ΔΔQTcF) was less than 10 ms (maximum, 3.9 ms at 18 h after dosing), indicating an absence of a clinically meaningful increase in the QTc interval. The lower limit of the 90% CI of ΔΔQTcF for moxifloxacin versus placebo was longer than 5 ms at all 5 time points selected for assay sensitivity analysis, demonstrating that the study was adequately sensitive to assess QTc prolongation. There was no positive relationship between delafloxacin plasma concentrations and ΔΔQTcF. Treatment-emergent adverse events (AEs) were more frequent among subjects receiving a single supratherapeutic dose of 900 mg delafloxacin. There were no deaths, serious AEs, or AEs leading to study discontinuation and no clinically meaningful abnormalities in laboratory values or vital signs observed at any time point after any dose of the study drug. PMID:25845864

Lacosamide cardiac safety: clinical trials in patients with partial-onset seizures.

PubMed

Rudd, G D; Haverkamp, W; Mason, J W; Wenger, T; Jay, G; Hebert, D; Doty, P; Horstmann, R

2015-11-01

To evaluate the cardiac safety of adjunctive lacosamide in a large pool of adults with partial-onset seizures (POS). Post-randomization changes from baseline for electrocardiographic (ECG) measurements, diagnostic findings, and relevant adverse events (AEs) were compared for pooled data from three randomized, placebo-controlled trials of adjunctive lacosamide for the treatment of POS. Lacosamide did not prolong the QTc interval or affect heart rate as determined by an analysis of data from patients randomized to lacosamide 200, 400, or 600 mg/day (n = 944) compared with placebo (n = 364). After 12-week maintenance treatment, mean changes from baseline for QRS duration were similar between the placebo and lacosamide 200 and 400 mg/day groups (0.0, -0.2, and 0.4 ms), but slightly increased for lacosamide 600 mg/day (2.3 ms). A small, dose-related mean increase in PR interval was observed (-0.3, 1.4, 4.4, and 6.6 ms for the placebo and lacosamide 200, 400, and 600 mg/day groups, respectively). First-degree atrioventricular (AV) block was reported as a non-serious AE in 0.0%, 0.7%, 0.2%, and 0.5% of patients in the same respective groups. Second- or higher degree AV block was not observed. There was no evidence of a PR-interval-related pharmacodynamic interaction of lacosamide with either carbamazepine or lamotrigine. Evaluation of the pooled cardiac safety data from patients with POS showed that adjunctive lacosamide at the maximum recommended dose (400 mg/day) was not clearly associated with any cardiac effect other than a small, dose-related increase in PR interval that had no evident symptomatic consequence. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The BUMP model of response planning: intermittent predictive control accounts for 10 Hz physiological tremor.

PubMed

Bye, Robin T; Neilson, Peter D

2010-10-01

Physiological tremor during movement is characterized by ∼10 Hz oscillation observed both in the electromyogram activity and in the velocity profile. We propose that this particular rhythm occurs as the direct consequence of a movement response planning system that acts as an intermittent predictive controller operating at discrete intervals of ∼100 ms. The BUMP model of response planning describes such a system. It forms the kernel of Adaptive Model Theory which defines, in computational terms, a basic unit of motor production or BUMP. Each BUMP consists of three processes: (1) analyzing sensory information, (2) planning a desired optimal response, and (3) execution of that response. These processes operate in parallel across successive sequential BUMPs. The response planning process requires a discrete-time interval in which to generate a minimum acceleration trajectory to connect the actual response with the predicted future state of the target and compensate for executional error. We have shown previously that a response planning time of 100 ms accounts for the intermittency observed experimentally in visual tracking studies and for the psychological refractory period observed in double stimulation reaction time studies. We have also shown that simulations of aimed movement, using this same planning interval, reproduce experimentally observed speed-accuracy tradeoffs and movement velocity profiles. Here we show, by means of a simulation study of constant velocity tracking movements, that employing a 100 ms planning interval closely reproduces the measurement discontinuities and power spectra of electromyograms, joint-angles, and angular velocities of physiological tremor reported experimentally. We conclude that intermittent predictive control through sequential operation of BUMPs is a fundamental mechanism of 10 Hz physiological tremor in movement. Copyright © 2010 Elsevier B.V. All rights reserved.

Determination of chlorine, sulfur and carbon in reinforced concrete structures by double-pulse laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Labutin, Timur A.; Popov, Andrey M.; Zaytsev, Sergey M.; Zorov, Nikita B.; Belkov, Mikhail V.; Kiris, Vasilii V.; Raikov, Sergey N.

2014-09-01

Accurate and reliable quantitative determination of non-metal corrosion agents in concrete is still an actual task of analytical use of LIBS. Two double-pulse LIBS systems were tested as a tool for the determination of chlorine, sulfur and carbon in concretes. Both systems had collinear configuration; a laboratory setup was equipped with an ICCD and two lasers (355/532 nm + 540 nm), but a CCD was a detector for a mobile system with one laser (1064 nm). Analytical lines of Cl I at 837.59 nm, S I at 921 nm and C I at 247.86 nm were used to plot calibration curves. Optimal interpulse delays for the laboratory setup were 4 μs for chlorine and 2.8 μs for carbon, while an interpulse delay of 2 μs was optimal for chlorine and sulfur determination with the mobile system. We suggested the normalization of the Cl I line at 837.59 nm to the Mg II line at 279.08 nm (visible at 837.23 nm in the third order) to compensate for pulse-to-pulse fluctuations of chlorine lines. It provided the decrease of the detection limit of chlorine from 400 ppm to 50 ppm. Therefore, we reported that LIBS can be used to determine main corrosive active substances under ambient conditions in concrete below critical threshold values. Moreover, the application of the mobile system for in-situ qualitative assessment of corrosion way of a steel cage of a swimming pool dome was also demonstrated. It was found that chloride corrosion due to the disinfection of water was the main way for corrosion of the open part steel and the steel rebar inside the concrete.

Laser-induced breakdown spectroscopy of bulk aqueous solutions at oceanic pressures: evaluation of key measurement parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michel, Anna P. M.; Lawrence-Snyder, Marion; Angel, S. Michael

The development of in situ chemical sensors is critical for present-day expeditionary oceanography and the new mode of ocean observing systems that we are entering. New sensors take a significant amount of time to develop; therefore, validation of techniques in the laboratory for use in the ocean environment is necessary. Laser-induced breakdown spectroscopy (LIBS) is a promising in situ technique for oceanography. Laboratory investigations on the feasibility of using LIBS to detect analytes in bulk liquids at oceanic pressures were carried out. LIBS was successfully used to detect dissolved Na, Mn, Ca, K, and Li at pressures up to 2.76x107more » Pa. The effects of pressure, laser-pulse energy, interpulse delay, gate delay, temperature, and NaCl concentration on the LIBS signal were examined. An optimal range of laser-pulse energies was found to exist for analyte detection in bulk aqueous solutions at both low and high pressures. No pressure effect was seen on the emission intensity for Ca and Na, and an increase in emission intensity with increased pressure was seen for Mn. Using the dual-pulse technique for several analytes, a very short interpulse delay resulted in the greatest emission intensity. The presence of NaCl enhanced the emission intensity for Ca, but had no effect on peak intensity of Mn or K. Overall, increased pressure, the addition of NaCl to a solution, and temperature did not inhibit detection of analytes in solution and sometimes even enhanced the ability to detect the analytes. The results suggest that LIBS is a viable chemical sensing method for in situ analyte detection in high-pressure environments such as the deep ocean.« less

Dynamics-based selective 2D 1H/1H chemical shift correlation spectroscopy under ultrafast MAS conditions

NASA Astrophysics Data System (ADS)

Zhang, Rongchun; Ramamoorthy, Ayyalusamy

2015-05-01

Dynamics plays important roles in determining the physical, chemical, and functional properties of a variety of chemical and biological materials. However, a material (such as a polymer) generally has mobile and rigid regions in order to have high strength and toughness at the same time. Therefore, it is difficult to measure the role of mobile phase without being affected by the rigid components. Herein, we propose a highly sensitive solid-state NMR approach that utilizes a dipolar-coupling based filter (composed of 12 equally spaced 90° RF pulses) to selectively measure the correlation of 1H chemical shifts from the mobile regions of a material. It is interesting to find that the rotor-synchronized dipolar filter strength decreases with increasing inter-pulse delay between the 90° pulses, whereas the dipolar filter strength increases with increasing inter-pulse delay under static conditions. In this study, we also demonstrate the unique advantages of proton-detection under ultrafast magic-angle-spinning conditions to enhance the spectral resolution and sensitivity for studies on small molecules as well as multi-phase polymers. Our results further demonstrate the use of finite-pulse radio-frequency driven recoupling pulse sequence to efficiently recouple weak proton-proton dipolar couplings in the dynamic regions of a molecule and to facilitate the fast acquisition of 1H/1H correlation spectrum compared to the traditional 2D NOESY (Nuclear Overhauser effect spectroscopy) experiment. We believe that the proposed approach is beneficial to study mobile components in multi-phase systems, such as block copolymers, polymer blends, nanocomposites, heterogeneous amyloid mixture of oligomers and fibers, and other materials.

Salivary testosterone measurement by liquid chromatography tandem mass spectrometry in adult males and females.

PubMed

Keevil, B G; MacDonald, P; Macdowall, W; Lee, D M; Wu, F C W

2014-05-01

Salivary testosterone (Sal-T) may be a useful surrogate of serum free testosterone. The study aims were to use a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) assay to determine whether Sal-T concentrations accurately reflect Sal-T concentrations in both sexes and to investigate practical aspects of sample collection. Saliva and serum samples were collected in 104 male and 91 female subjects. A more sensitive LC-MS/MS assay was developed to enable Sal-T quantitation in the low concentrations found in females. Saliva (200 µL) was extracted with 1 mL of methyl-tert-butyl ether following the addition of D5-testosterone. Quantitation was performed using a Waters TQ-S mass spectrometer. The assay achieved a lower limit of quantification of 5 pmol/L, sufficiently sensitive to measure testosterone in female saliva. Sal-T showed a diurnal variation but samples taken at weekly and monthly intervals showed no significant differences. Sal-T was stable at ambient temperature for up to 5 days, after freeze-thawing and 3 years frozen storage. Reference intervals for Sal-T were 93-378 pmol/L in males and 5-46 pmol/L in females. Sal-T correlated significantly with serum calculated free-T in males (r = 0.71, P < 0.001) and in females (r = 0.39, P < 0.001). These results confirm that testosterone can be reliably and accurately measured by LC-MS/MS in both adult male and female saliva samples. These results lay the foundation for further exploration of the clinical application of Sal- T as a reliable alternative to serum testosterone in the diagnosis and management of androgen disorders and assessment of androgen status in clinical research.

Association between serum uric acid, metabolic syndrome and microalbuminuria in previously untreated essential hypertensive patients.

PubMed

Rodilla, Enrique; Pérez-Lahiguera, Francisco; Costa, José A; González, Carmen; Miralles, Amparo; Moral, Desamparados; Pascual, José María

2009-01-17

The aim of the study was to assess the association of serum uric acid levels with microalbuminuria -urinary albumin excretion (UAE)> or = 30mg/24h-. Cross-sectional study in 429 (220 women) hypertensive, non diabetic, never treated patients (mean age: 47 years) with glomerular filtration rate > or =60ml/min/1.73m(2). The prevalence of microalbuminuria was 20.5%; 18% had hyperuricemia and 47% fulfilled the criteria for metabolic syndrome (MS). Baseline UAE correlated in the unvaried analysis to diastolic blood pressure, waist circumference, high-density lipoprotein cholesterol and uric acid. In multiple linear regression models, only MS (beta=0.113; p=0.03), and serum uric acid values (beta=0.04; p=0.05) were independently associated with logUAE, after adjustment for age and sex. Hyperuricemia (serum uric acid level > or =7.0mg/dl for men and > or =6.5mg/dl for women; odds ratio=2.18; 95% confidence interval, 1.21-3.92; p=0.010), and MS (odds ratio=2.16; 95% confidence interval, 1.32-3.53; p=0.002) were independently associated with a higher risk of microalbuminuria in multiple logistic regression analyses. The prevalence of microalbuminuria was 45.8% in patients with coexistent MS and hyperuricemia, as compared to 13.6% in hypertensive patients without it (p<0.001). In patients with concomitant MS and hyperuricemia the probability of being microalbuminuric was 3.7 times higher than in patients without those factors. Serum uric acid level is associated with microalbuminuria. Coexistence of MS and hyperuricemia in hypertensive patients increases almost 4 times the odds of being microalbuminuric.

Prolonged QRS Widening After Aripiprazole Overdose.

PubMed

Mazer-Amirshahi, Maryann; Porter, Robert; Dewey, Kayla

2018-05-05

Aripiprazole is an atypical antipsychotic with a long half-life. Overdose can result in protracted somnolence and cardiac disturbances, particularly QT interval prolongation. This is a single case report of a 14-year-old boy who took an overdose of aripiprazole and developed QRS widening. A 14-year-old boy intentionally ingested 20 tablets of aripiprazole (5 mg). He was brought to the emergency department when his ingestion was discovered. The patient's vital signs were as follows: temperature, 37.7°C; heart rate, 108 beats/min; blood pressure, 138/98 mm Hg; and respirations, 16 breaths/min. Activated charcoal was administered within 90 minutes of ingestion. Initial electrocardiogram (EKG) showed sinus tachycardia, with a QRS of 138 ms and QT interval of 444 ms. QRS duration was 90 ms on an EKG performed 3 months earlier. A bolus of sodium bicarbonate was administered, and the patient was transferred to the pediatric intensive care unit. Repeat EKG demonstrated a QRS of 156 ms, and a sodium bicarbonate infusion was initiated. The patient continued to have QRS prolongation for the next 8 days, reaching a peak of 172 ms 3 days postingestion. Despite aggressive treatment with sodium bicarbonate, there was persistent QRS prolongation; however, the patient did not have any dysrhythmias and remained hemodynamically stable. The patient was discharged 9 days postingestion when the QRS duration normalized to 82 ms. Genetic testing revealed that the patient was a CYP2D6 poor metabolizer. This case suggests that aripiprazole toxicity may possibly be associated with QRS prolongation without associated dysrhythmias or cardiovascular compromise. In addition, toxicity may be prolonged in patients who are CYP2D6 poor metabolizers.

Gender differences in the electrocardiogram screening of athletes.

PubMed

Bessem, Bram B; de Bruijn, Matthijs M C; Nieuwland, Wybe W

2017-02-01

Gender-related differences are frequently used in medicine. Electrocardiograms are also subject to such differences. This study evaluated gender differences in ECG parameters of young athletes, discussing the possible implications of these differences for ECG criteria used in the cardiovascular screening of young athletes. Observational cross-sectional study. In 2013 and 2014 all the ECGs from the cardiovascular screenings performed at University Sports Medical Centre in Groningen of the student athletes who wanted to participate in a college sports program were collected. The ECG characteristics were scored using computer-based measurements and the Seattle ECG criteria. The study population included 1436 athletes, of which 72% were male. Male athletes were older (19.3 years vs. 18.6 years), participated in sports more frequently (4.0/week vs. 3.8/week) and spent more hours per week practising sports (6.4h/week vs. 5.8h/week) than female athletes. Male athletes had significantly higher PR intervals (149ms vs. 141ms), lead voltages and QRS duration (98ms vs. 88ms). Female athletes had significantly higher resting heart rates (69/min vs. 64/min) and QTc intervals (407ms vs. 400ms). Male athletes also had significantly higher amounts of sinus bradycardia (38.3% vs. 23.0%), incomplete RBBB (15.0% vs. 3.7%), early repolarisation (4.5% vs. 1.0%) and isolated QRS voltage criteria for LVH (26.3% vs. 4.6%). All P-values were ≤0.001. ECGs of young athletes demonstrate gender-related differences. These differences could be considered in their cardiovascular screening. For the Seattle ECG criteria we advise additional research into the clinical implications of using gender-based cut-off values for the QRS duration in the intraventricular conduction delay criterion. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Mental stress test: a rapid, simple, and efficient test to unmask long QT syndrome.

PubMed

Etienne, Pauline; Huchet, François; Gaborit, Nathalie; Barc, Julien; Thollet, Aurélie; Kyndt, Florence; Guyomarch, Béatrice; Le Marec, Hervé; Charpentier, Flavien; Schott, Jean-Jacques; Redon, Richard; Probst, Vincent; Gourraud, Jean-Baptiste

2018-04-20

QT prolongation during mental stress test (MST) has been associated with familial idiopathic ventricular fibrillation. In long QT syndrome (LQTS), up to 30% of mutation carriers have normal QT duration. Our aim was to assess the QT response during MST, and its accuracy in the diagnosis of concealed LQTS. All patients who are carrier of a KCNQ1 or KCNH2 mutations without QT prolongation were enrolled. A control group was constituted of patients with negative exercise and epinephrine tests. Electrocardiogram were recorded at rest and at the maximum heart rate during MST and reviewed by two physicians. Among the 70 patients enrolled (median age 41±2.1 years, 46% male), 36 were mutation carrier for LQTS (20 KCNQ1 and 16 KCNH2), and 34 were controls. KCNQ1 and KCNH2 mutation carriers presented a longer QT interval at baseline [405(389; 416) and 421 (394; 434) ms, respectively] compared with the controls [361(338; 375)ms; P < 0.0001]. QT duration during MST varied by 9 (4; 18) ms in KCNQ1, 3 (-6; 16) ms in KCNH2, and by -22 (-29; -17) ms in controls (P < 0.0001). These QT variations were independent of heart rate (P < 0.3751). Receiver operating characteristic curve analysis identified a cut-off value of QT variation superior to -11 ms as best predictor of LQTS. It provided 97% sensitivity and 97% specificity of QT prolongation in the diagnosis of LQTS. We identified a paradoxical response of the QT interval during MST in LQTS. Easy to assess, MST may be efficient to unmask concealed LQTS in patients at risk of this pathology.

Effect of Left Cardiac Sympathetic Denervation on the Electromechanical Window in Patients with either Type 1 or Type 2 Long QT Syndrome: A Pilot Study.

PubMed

Schneider, Andrew E; Bos, J Martijn; Ackerman, Michael J

2016-09-01

Left cardiac sympathetic denervation (LCSD) exerts significant antifibrillatory effects in patients with long QT syndrome (LQTS). Recently, electromechanical window (EMW) has emerged as a novel torsadogenic marker in LQTS, superior to QT interval (QTc) in distinguishing symptomatic from asymptomatic patients. To explore the hypothesis that LCSD improves EMW most favorably in patients with LQT1. From September 2006 to July 2015, 44 LQT1 and 25 LQT2 patients underwent LCSD. Subset analysis was performed on the six LQT1 and seven LQT2 patients who had echocardiograms both pre-LCSD and ≥3 months post-LCSD. EMW is defined as the time difference (ms) between aortic valve closure and the end of the QT interval, measured from an ECG on the concurrent echocardiogram. Compared to published normal EMW values of 22 ± 19 ms, pre-LCSD EMW mean values were -78 ± 36 ms in LQT1 and -71 ± 35 ms in LQT2 (P < .001). Following LCSD, there was a 57 ± 35 ms decrease in QTc in LQT1 (P = .16) and 23 ± 21 ms decrease in QTc in LQT2 (P = .3). Overall, there was a 35 ± 57 ms mean improvement in EMW post-LCSD (P = .04). Five of the 6 (83%) LQT1 subjects had a favorable EMW change post-LCSD (mean improvement 56 ± 25 ms, P = .04). Five of the 7 (71%) LQT2 subjects had a favorable EMW change post-LCSD (mean improvement 18 ± 19 ms, P = .2). The precise mechanism of the LCSD therapeutic effect in LQTS patients is not fully understood. This pilot study raises the possibility that LCSD's antitorsadogenic effect in patients with LQT1 could be conferred in part by restoration of electromechanical order, evidenced by normalization of the EMW. © 2016 Wiley Periodicals, Inc.

Compendium of the FY1990 and FY1992 Research Reviews for the Research Methods Branch

DTIC Science & Technology

1994-09-01

the perfusion technique, the perfusion was not done in situ. Trout were anesthetized with MS-222 (3-aminobenzoic acid ethyl ester, Sigma Chemical...by a trypan blue exclusion test. Medaka Medaka were anesthetized with MS-222, transferred to a dissecting tray, and incised from the urogenital pore...Histology General histology was compared at intervals of 20 days. Fish were anesthetized , fixed, and processed for paraffin embedment, and sections

Duty factor variation possibility from 1% to 100% with PKU microwave driven Cs-free volume H{sup −} sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, S. X., E-mail: sxpeng@pku.edu.cn; Zhang, T.; Ren, H. T.

Microwave driven cesium-free volume H{sup −} sources, that have the ability to deliver tens of mA H{sup −} at 35 keV both in CW and 10% duty factor (100 Hz/1 ms), were developed at Peking University (PKU) [S. X. Peng et al., in Proceeding of IPAC 2015, WEPWA027, Richmond, Virginia, USA, 3–8 May 2015]. Recently, special efforts were paid on the investigation of duty factor variation possibility from 1% to 100% with them. Most of the experiments were carried out with a pulsed length (τ) of 1 ms and different intervals of 99 ms, 49 ms, 39 ms, 29 ms,more » 19 ms, 9 ms, 4 ms, 2 ms, 1 ms, 0.5 ms, and 0 ms, respectively. Other experiments were focused on CW operation and fixed duty factor of 1%. Experimental results prove that PKU H{sup −} sources can deliver tens of mA H{sup −} at duty factor from 1% to 100%. The RF power efficiency increases steadily with the increasing of duty factor from 1% to CW at a fixed pulsed length. Under a given duty factor and pulsed length, RF power efficiency keeps constant and the H{sup −} current increases with RF power linearly. Details will be presented in the paper.« less

Thunderstorm vertical velocities and mass flux estimated from satellite data

NASA Technical Reports Server (NTRS)

Adler, R. F.; Fenn, D. D.

1979-01-01

Infrared geosynchronous satellite data with an interval of five minutes between images are used to estimate thunderstorm top ascent rates on two case study days. A mean vertical velocity of 3.5/ms for 19 clouds is calculated at a height of 8.7 km. This upward motion is representative of an area of approximately 10km on a side. Thunderstorm mass flux of approximately 2x10 to the 11th power/gs is calculated, which compares favorably with previous estimates. There is a significant difference in the mean calculated vertical velocity between elements associated with severe weather reports (w bar=4.6/ms) and those with no such reports (2.5/ms). Calculations were made using a velocity profile for an axially symmetric jet to estimate the peak updraft velocity. For the largest observed w value of 7.8/ms the calculation indicates a peak updraft of approximately 50/ms.

Evaluation of Tp-e interval and Tp-e/QT ratio in patients with ankylosing spondylitis.

PubMed

Acar, Gurkan; Yorgun, Hikmet; Inci, Mehmet Fatih; Akkoyun, Murat; Bakan, Betul; Nacar, Alper Bugra; Dirnak, Imran; Cetin, Gozde Yildirim; Bozoglan, Orhan

2014-03-01

Ankylosing spondylitis (AS) is a chronic multi-systemic inflammatory rheumatic disorder. Several studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the transmural dispersion of repolarization and that increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. The aim of this study was to evaluate ventricular repolarization by using Tp-e interval and Tp-e/QT ratio in patients with AS, and to assess the relation with inflammation. Sixty-two patients with AS and 50 controls were included. Tp-e interval and Tp-e/QT ratio were measured from a 12-lead electrocardiogram, and the Tp-e interval corrected for heart rate. The plasma level of high sensitive C-reactive protein (hsCRP) was measured. These parameters were compared between groups. In electrocardiographic parameters analysis, QT dispersion (QTd) and corrected QTd were significantly increased in AS patients compared to the controls (31.7 ± 9.6 vs 28.2 ± 7.4 and 35.8 ± 11.5 vs 30.6 ± 7.9 ms, P = 0.03 and P = 0.007, respectively). cTp-e interval and Tp-e/QT ratio were also significantly higher in AS patients (92.1 ± 10.2 vs 75.8 ± 8.4 and 0.22 ± 0.02 vs 0.19 ± 0.02 ms, all P values <0.001). cTp-e interval and Tp-e/QT ratio were significantly correlated with hsCRP (r = 0.63, P < 0.001 and r = 0.49, P < 0.001, respectively). Our study revealed that Tp-e interval and Tp-e/QT ratio were increased in AS patients. These electrocardiographic ventricular repolarization indexes were significantly correlated with the plasma level of hsCRP.

Evaluation of Tp-e interval and Tp-e/QT ratio in patients with ankylosing spondylitis.

PubMed

Acar, Gurkan; Yorgun, Hikmet; Inci, Mehmet Fatih; Akkoyun, Murat; Bakan, Betul; Nacar, Alper Bugra; Dirnak, Imran; Cetin, Gozde Yildirim; Bozoglan, Orhan

2013-04-12

OBJECTIVES: Ankylosing spondylitis (AS) is a chronic multi-systemic inflammatory rheumatic disorder. Several studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the transmural dispersion of repolarization and that increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. The aim of this study was to evaluate ventricular repolarization by using Tp-e interval and Tp-e/QT ratio in patients with AS, and to assess the relation with inflammation. METHODS: Sixty-two patients with AS and 50 controls were included. Tp-e interval and Tp-e/QT ratio were measured from a 12-lead electrocardiogram, and the Tp-e interval corrected for heart rate. The plasma level of high sensitive C-reactive protein (hsCRP) was measured. These parameters were compared between groups. RESULTS: In electrocardiographic parameters analysis, QT dispersion (QTd) and corrected QTd were significantly increased in AS patients compared to the controls (31.7 ± 9.6 vs 28.2 ± 7.4 and 35.8 ± 11.5 vs 30.6 ± 7.9 ms, P = 0.03 and P = 0.007, respectively). cTp-e interval and Tp-e/QT ratio were also significantly higher in AS patients (92.1 ± 10.2 vs 75.8 ± 8.4 and 0.22 ± 0.02 vs 0.19 ± 0.02 ms, all P values <0.001). cTp-e interval and Tp-e/QT ratio were significantly correlated with hsCRP (r = 0.63, P < 0.001 and r = 0.49, P < 0.001, respectively). CONCLUSIONS: Our study revealed that Tp-e interval and Tp-e/QT ratio were increased in AS patients. These electrocardiographic ventricular repolarization indexes were significantly correlated with the plasma level of hsCRP.

Autonomic adaptation after traditional and reverse swimming training periodizations.

PubMed

Clemente-Suárez, Vicente Javier; Fernandes, R J; Arroyo-Toledo, J J; Figueiredo, P; González-Ravé, J M; Vilas-Boas, J P

2015-03-01

The objective of the present study was to analyze the autonomic response of trained swimmers to traditional and reverse training periodization models. Seventeen swimmers were divided in two groups, performing a traditional periodization (TPG) or a reverse periodization (RPG) during a period of 10 weeks. Heart rate variability and 50 m swimming performance were analyzed before and after the training programs. After training, the TPG decreased the values of the high frequency band (HF), the number of differences between adjacent normal R-R intervals longer than 50 ms (NN50) and the percentage of differences between adjacent normal R-R intervals more than 50 ms (pNN50), and the RPG increased the values of HF and square root of the mean of the sum of the squared differences between adjacent normal R-R intervals (RMSSD). None of the groups improved significantly their performance in the 50-m test. The autonomic response of swimmers was different depending on the periodization performed, with the reverse periodization model leading to higher autonomic adaption. Complementary, the data suggests that autonomic adaptations were not critical for the 50-m swimming performance.

Kinetics of fast short-term depression are matched to spike train statistics to reduce noise.

PubMed

Khanbabaie, Reza; Nesse, William H; Longtin, Andre; Maler, Leonard

2010-06-01

Short-term depression (STD) is observed at many synapses of the CNS and is important for diverse computations. We have discovered a form of fast STD (FSTD) in the synaptic responses of pyramidal cells evoked by stimulation of their electrosensory afferent fibers (P-units). The dynamics of the FSTD are matched to the mean and variance of natural P-unit discharge. FSTD exhibits switch-like behavior in that it is immediately activated with stimulus intervals near the mean interspike interval (ISI) of P-units (approximately 5 ms) and recovers immediately after stimulation with the slightly longer intervals (>7.5 ms) that also occur during P-unit natural and evoked discharge patterns. Remarkably, the magnitude of evoked excitatory postsynaptic potentials appear to depend only on the duration of the previous ISI. Our theoretical analysis suggests that FSTD can serve as a mechanism for noise reduction. Because the kinetics of depression are as fast as the natural spike statistics, this role is distinct from previously ascribed functional roles of STD in gain modulation, synchrony detection or as a temporal filter.

Dual mechanisms in the perceptual processing of click train temporal regularity.

PubMed

Phillips, Dennis P; Dingle, Rachel N; Hall, Susan E; Jang, Moragh

2012-07-01

Two experiments measured human sensitivity to temporal jitter in 25-click trains with inter-click intervals (ICIs) between 5 and 100 ms. In a naturalistic experiment using wideband clicks, jitter thresholds were a nonmonotonic function of ICI, peaking for ICIs near 40-60 ms. In a subsequent experiment, clicks were high-passed and presented against a low-frequency noise masker. Jitter threshold vs ICI functions lost the positive slope over short ICIs but retained the negative slope at long ICIs. The same behavior was seen in click rate discrimination tasks. Different processes mediate regularity analysis for click trains with ICIs above and below 40-60 ms.

Multiple sclerosis in North African migrants to France.

PubMed

Kurtzke, J F; Delasnerie-Lauprêtre, N; Wallin, M T

1998-11-01

Among some 7500 respondents with known place of birth who had completed a nationwide questionnaire survey for multiple sclerosis (MS) in France in 1986, there were 260 born in former French North Africa (Algeria, Morocco, Tunisia). They had migrated to France between 1923 and 1986, but 66% came between 1956 and 1964. Two-thirds were from Algeria, where virtually the entire European population had emigrated in 1962 at the end of the Algerian war for independence. The migrants were younger at prevalence day (mean 43.4 years) and at onset (29.4 years) than the French-born MS (46.6; 31.3 years). Eight migrants lacked age information. The 225 migrants with onset more than 1 year after immigration presumably acquired their MS in France. They provided an age adjusted (US 1960) MS prevalence rate 1.54 times that for all France. If the latter is taken at 50 per 100,000 population their estimated adjusted rate is 76.8 with 95% confidence interval of 67.1 to 87.5. The other 27 with presumed acquisition in North Africa gave an estimated adjusted prevalence of 16.6 per 100,000 (95% CI 10.9-24.1). For those migrants with acquisition in France there was a mean interval of 13 years between immigration or age 11 and clinical onset, with a minimum of 3 years. This series provides further support for the theses: 1) that MS is primarily an environmental disease acquired after childhood; 2) that acquisition requires prolonged or repeated exposure (here 3 years for these medium-to-high MS risk migrants) followed by a prolonged latent or incubation period between acquisition and symptom onset (here 10 years); and 3) that this disease is most likely a widespread but unknown persistent infection which results in clinical MS in only a small proportion of those affected.

Effects of ATX-MS-1467 immunotherapy over 16 weeks in relapsing multiple sclerosis.

PubMed

Chataway, Jeremy; Martin, Keith; Barrell, Kevin; Sharrack, Basil; Stolt, Pelle; Wraith, David C

2018-03-13

To assess safety, tolerability, and efficacy of the antigen-specific immunotherapy ATX-MS-1467 in participants with relapsing multiple sclerosis using different treatment protocols to induce tolerance. Two open-label trials in adult participants with relapsing multiple sclerosis were conducted. Study 1 was a multicenter, phase 1b safety evaluation comparing intradermal (i.d.) (cohort 1) with subcutaneous (cohort 2) administration in 43 participants. Both cohorts received ATX-MS-1467 dosed at 25, 50, 100, 400, and 800 μg at 14-day intervals over 8 weeks, followed by 8 weeks with 4 additional 800-μg doses at 14-day intervals and 32 weeks off study medication. Study 2 was a phase 2a, multicenter, single-arm trial enrolling 37 participants. ATX-MS-1467 was titrated from 50 μg i.d. on day 1 to 200 μg on day 15 and 800 μg on day 29 followed by biweekly administration of 800 μg for 16 weeks and 16 weeks off study medication. Efficacy was evaluated on MRI parameters and clinical variables. Safety endpoints included treatment-emergent adverse events and injection-site reactions. In study 1, there was a significant decrease in new/persisting T1 gadolinium-enhanced (GdE) lesions in cohort 1 from baseline to week 16, returning to baseline values at week 48. In study 2, the number of T1 GdE lesions were significantly reduced on treatment and remained reduced at study completion. Safety results were unremarkable in both studies. Relatively slow ATX-MS-1467 titration and a longer full-dose i.d. treatment period is associated with reduction in GdE lesions and a sustained effect post treatment. Further trials of ATX-MS-1467 are warranted. This work provides Class IV evidence that for patients with relapsing multiple sclerosis, slow ATX-MS-1467 titration and a longer full-dose i.d. treatment period is associated with reduction in GdE lesions. © 2018 American Academy of Neurology.

HIGH-TIME-RESOLUTION MEASUREMENTS OF THE POLARIZATION OF THE CRAB PULSAR AT 1.38 GHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Słowikowska, Agnieszka; Stappers, Benjamin W.; Harding, Alice K.

2015-01-20

Using the Westerbork Synthesis Radio Telescope, we obtained high-time-resolution measurements of the full polarization of the Crab pulsar. At a resolution of 1/8192 of the 34 ms pulse period (i.e., 4.1 μs), the 1.38 GHz linear-polarization measurements are in general agreement with previous lower-time-resolution 1.4 GHz measurements of linear polarization in the main pulse (MP), in the interpulse (IP), and in the low-frequency component (LFC). We find the MP and IP to be linearly polarized at about 24% and 21% with no discernible difference in polarization position angle. However, contrary to theoretical expectations and measurements in the visible, we find nomore » evidence for significant variation (sweep) in the polarization position angle over the MP, the IP, or the LFC. We discuss the implications, which appear to be in contradiction to theoretical expectations. We also detect weak circular polarization in the MP and IP, and strong (≈20%) circular polarization in the LFC, which also exhibits very strong (≈98%) linear polarization at a position angle of 40° from that of the MP or IP. The properties are consistent with the LFC, which is a low-altitude component, and the MP and IP, which are high-altitude caustic components. Current models for the MP and IP emission do not readily account for the absence of pronounced polarization changes across the pulse. We measure IP and LFC pulse phases relative to the MP consistent with recent measurements, which have shown that the phases of these pulse components are evolving with time.« less

A case-control study of risk factors for multiple sclerosis in Iran.

PubMed

Alonso, Alvaro; Cook, Stuart D; Maghzi, Amir-Hadi; Divani, Afshin A

2011-05-01

Numerous studies have assessed risk factors for multiple sclerosis (MS), although none have been conducted previously in Iran. The objective of this study was to study lifestyle and environmental risk factors of MS in the Iranian population. A case-control study, including 394 MS cases and 394 matched controls, was conducted in MS clinics in different Iranian cities. Information on lifestyles, environmental exposures, and past medical history was obtained from medical charts and phone interviews. In multivariable analysis, sunlight exposure was associated with a lower risk of MS: the odds ratio (OR) and 95% confidence interval (CI) of MS associated with a 1-h increment in daily sunlight was 0.62 (0.53-0.73). Smoking was associated with MS risk in women (OR: 6.48, 95% CI: 1.46-28.78), but not in men (OR: 0.72, 95% CI: 0.31-1.68) (p=0.002 for interaction). Finally, past history of common surgical procedures, infectious disorders, or exposure to pets and farm animals was not associated with MS risk. Different modifiable lifestyles, including sunlight exposure and smoking, were associated with lower MS risk in Iran. Interventions aimed at promoting smoking cessation and, more importantly, at increasing exposure to sunlight might contribute to the prevention of MS.

Real time SAR processing

NASA Technical Reports Server (NTRS)

Premkumar, A. B.; Purviance, J. E.

1990-01-01

A simplified model for the SAR imaging problem is presented. The model is based on the geometry of the SAR system. Using this model an expression for the entire phase history of the received SAR signal is formulated. From the phase history, it is shown that the range and the azimuth coordinates for a point target image can be obtained by processing the phase information during the intrapulse and interpulse periods respectively. An architecture for a VLSI implementation for the SAR signal processor is presented which generates images in real time. The architecture uses a small number of chips, a new correlation processor, and an efficient azimuth correlation process.

Interaction of paired cortical and peripheral nerve stimulation on human motor neurons.

PubMed

Poon, David E; Roy, Francois D; Gorassini, Monica A; Stein, Richard B

2008-06-01

This paper contrasts responses in the soleus muscle of normal human subjects to two major inputs: the tibial nerve (TN) and the corticospinal tract. Paired transcranial magnetic stimulation (TMS) of the motor cortex at intervals of 10-25 ms strongly facilitated the motor evoked potential (MEP) produced by the second stimulus. In contrast, paired TN stimulation produced a depression of the reflex response to the second stimulus. Direct activation of the pyramidal tract did not facilitate a second response, suggesting that the MEP facilitation observed using paired TMS occurred in the cortex. A TN stimulus also depressed a subsequent MEP. Since the TN stimulus depressed both inputs, the mechanism is probably post-synaptic, such as afterhyperpolarization of motor neurons. Presynaptic mechanisms, such as homosynaptic depression, would only affect the pathway used as a conditioning stimulus. When TN and TMS pulses were paired, the largest facilitation occurred when TMS preceded TN by about 5 ms, which is optimal for summation of the two pathways at the level of the spinal motor neurons. A later, smaller facilitation occurred when a single TN stimulus preceded TMS by 50-60 ms, an interval that allows enough time for the sensory afferent input to reach the sensory cortex and be relayed to the motor cortex. Other work indicates that repetitively pairing nerve stimuli and TMS at these intervals, known as paired associative stimulation, produces long-term increases in the MEP and may be useful in strengthening residual pathways after damage to the central nervous system.

Comparison of single bout effects of bicycle training versus locomotor training on paired reflex depression of the soleus H-reflex after motor incomplete spinal cord injury.

PubMed

Phadke, Chetan P; Flynn, Sheryl M; Thompson, Floyd J; Behrman, Andrea L; Trimble, Mark H; Kukulka, Carl G

2009-07-01

To examine paired reflex depression changes post 20-minute bout each of 2 training environments: stationary bicycle ergometer training (bicycle training) and treadmill with body weight support and manual assistance (locomotor training). Pretest-posttest repeated-measures. Locomotor laboratory. Motor incomplete SCI (n=12; mean, 44+/-16y); noninjured subjects (n=11; mean, 30.8+/-8.3y). All subjects received each type of training on 2 separate days. Paired reflex depression at different interstimulus intervals (10 s, 1 s, 500 ms, 200 ms, and 100 ms) was measured before and after both types of training. (1) Depression was significantly less post-SCI compared with noninjured subjects at all interstimulus intervals and (2) post-SCI at 100-millisecond interstimulus interval: reflex depression significantly increased postbicycle training in all SCI subjects and in the chronic and spastic subgroups (P<.05). Phase-dependent regulation of reflex excitability, essential to normal locomotion, coordinated by pre- and postsynaptic inhibitory processes (convergent action of descending and segmental inputs onto spinal circuits) is impaired post-SCI. Paired reflex depression provides a quantitative assay of inhibitory processes contributing to phase-dependent changes in reflex excitability. Because bicycle training normalized reflex depression, we propose that bicycling may have a potential role in walking rehabilitation, and future studies should examine the long-term effects on subclinical measures of reflex activity and its relationship to functional outcomes.

Prognostic value of free light chains lambda and kappa in early multiple sclerosis.

PubMed

Voortman, Margarete M; Stojakovic, Tatjana; Pirpamer, Lukas; Jehna, Margit; Langkammer, Christian; Scharnagl, Hubert; Reindl, Markus; Ropele, Stefan; Seifert-Held, Thomas; Archelos, Juan-Jose; Fuchs, Siegrid; Enzinger, Christian; Fazekas, Franz; Khalil, Michael

2017-10-01

Cerebrospinal fluid (CSF) immunoglobulin free light chains (FLC) have been suggested as quantitative alternative to oligoclonal bands (OCB) in the diagnosis of multiple sclerosis (MS). However, little is known on their role in predicting clinical and paraclinical disease progression, particularly in early stages. To assess the prognostic value of FLC in OCB-positive patients with clinically isolated syndrome (CIS) suggestive of MS and early MS. We determined FLC kappa (KFLC) and lambda (LFLC) in CSF and serum by nephelometry in 61 patients (CIS ( n = 48), relapsing-remitting multiple sclerosis ( n = 13)) and 60 non-inflammatory neurological controls. Median clinical follow-up time in CIS was 4.8 years (interquartile range (IQR), 1.5-6.5 years). Patients underwent 3T magnetic resonance imaging (MRI) at baseline and follow-up (median time interval, 2.2 years; IQR, 1.0-3.7 years) to determine T2 lesion load (T2LL) and percent brain volume change (PBVC). CSF FLC were significantly increased in CIS/MS compared to controls (all p < 0.001). A lower KFLC/LFLC CSF ratio was associated with CIS-clinically definite multiple sclerosis (CDMS) conversion (hazard ratio (HR) = 2.89; 95% confidence interval (CI) = 1.17-7.14; p < 0.05). No correlations were found for FLC variables with T2LL or PBVC. Our study confirms increased intrathecal synthesis of FLC in CIS/MS which supports their diagnostic contribution. The KFLC/LFLC CSF ratio appears to have a prognostic value in CIS beyond OCB.

An increasing electromechanical window is a predictive marker of ventricular fibrillation in anesthetized rabbit with ischemic heart.

PubMed

Limprasutr, Vudhiporn; Pirintr, Prapawadee; Kijtawornrat, Anusak; Hamlin, Robert L

2018-05-10

The QTc interval is widely used in Safety Pharmacological studies to predict arrhythmia risk, and the electromechanical window (EMW) and short-term variability of QT intervals (STV QT ) have been studied as new biomarkers for drug-induced Torsades de Pointes (TdP). However, the use of EMW and STV QT to predict ventricular fibrillation (VF) has not been elucidated. This study aimed to evaluate EMW and STV QT to predict VF in anesthetized rabbit model of VF. VF was induced by ligation of the left anterior descending and a descending branch of the left circumflex coronary arteries in a sample population of rabbits (n=18). VF was developed 55.6% (10/18). In rabbit with VF, the EMW was significantly higher than in rabbits without VF (96.3 ± 15.6 ms and 49.5 ± 5.6 ms, respectively, P<0.05). STV QT had significantly increased before the onset of VF in rabbits that experienced VF, but not in rabbits that did not experience VF (11.7 ± 1.8 ms and 3.7 ± 0.4 ms, respectively, P<0.05). The EMW and STV QT had better predictive power for VF with higher sensitivity and specificity than the QTc measure. The result suggested that the increasing of EMW, as well as the elevation of STV QT , can potentially be used as biomarkers for predicting of VF.

Disruption of trace conditioning of the nictitating membrane response in rabbits by central cholinergic blockade.

PubMed

Kaneko, T; Thompson, R F

1997-05-01

Central muscarinic cholinergic involvement in classical conditioning of eyeblink responses was determined in trace and delay paradigms. Rabbits were trained on a trace procedure in which a 250-ms tone conditioned stimulus (CS) and a 100-ms air-puff unconditioned stimulus (UCS) were presented with a 500-ms trace interval. Each training session day consisted of ten tone alone, ten air-puff alone and 80 paired CS-UCS trials. Scopolamine hydrochloride at doses of 0.03 and 0.1 mg/0.5 ml per kg, s.c. dose-dependently disrupted acquisition of conditioned responses. Rabbits that were treated with scopolamine and failed to learn showed a gradual increase in conditioned responses during an additional training period with saline injections and no transfer from earlier training. Scopolamine methyl bromide, which does not appreciably cross the blood-brain barrier, showed no effects in the trace conditioning paradigm at a dose of 0.1 mg/kg, s.c., indicating central cholinergic blockade is responsible for the suppressive effect of scopolamine. Scopolamine hydrochloride at a dose of 0.1 mg/kg, s.c. did not block acquisition in the delay procedure with a 250-ms inter-stimulus interval, although the rate of acquisition was somewhat reduced by the drug. These data are the first to demonstrate that classical conditioning of the eyeblink response in the trace procedure is highly sensitive to central cholinergic deficits.

A sensitive LC-MS/MS method for the quantification of urinary 8-iso-prostaglandin F2α (8-iso-PGF2α) including pediatric reference interval.

PubMed

Xiao, Yi; Fu, Xiaowei; Pattengale, Paul; Dien Bard, Jennifer; Xu, Yan-Kang; O'Gorman, Maurice R

2016-09-01

Oxidative stress has been implicated in numerous diseases, including arthritis, atherosclerosis, Alzheimer's disease, cancer, diabetes, hypertension, and inflammation. 8-iso-prostaglandin F2α, a member of the F2 isoprostane family, has been well-accepted as a valuable biomarker for the assessment of oxidative stress. We report the development and validation of an ultra-sensitive LC-MS/MS assay for urinary 8-iso-PGF2α measurements in pediatric population. The assay was linear from 0.024 to 20nmol/l (R(2)=0.99). Recoveries were above 85% and matrix effects were below 5%. The variability was determined at nmol/l concentration: the intra-day variability (%CV) ranged from 3.9% to 4.5% (n=20); and the inter-day variability ranged from 4.3% to 5.7% (n=20). The accuracy of our laboratory developed test was evaluated with a clinical reference laboratory (n=39), and a correlation coefficient of 0.9257 was observed. Reference interval were established to be <0.5ng/mg creatinine in a group of pediatric population (2months-18years, n=123). The precision of the assay will allow for accurate assessment of oxidative stress, and is acceptable for patient testing, particularly in pediatric population. Copyright © 2016 Elsevier B.V. All rights reserved.

The contribution of waveform interactions to the perception of concurrent vowels.

PubMed

Assmann, P F; Summerfield, Q

1994-01-01

Models of the auditory and phonetic analysis of speech must account for the ability of listeners to extract information from speech when competing voices are present. When two synthetic vowels are presented simultaneously and monaurally, listeners can exploit cues provided by a difference in fundamental frequency (F0) between the vowels to help determine their phonemic identities. Three experiments examined the effects of stimulus duration on the perception of such "double vowels." Experiment 1 confirmed earlier findings that a difference in F0 provides a smaller advantage when the duration of the stimulus is brief (50 ms rather than 200 ms). With brief stimuli, there may be insufficient time for attentional mechanisms to switch from the "dominant" member of the pair to the "nondominant" vowel. Alternatively, brief segments may restrict the availability of cues that are distributed over the time course of a longer segment of a double vowel. In experiment 1, listeners did not perform better when the same 50-ms segment was presented four times in succession (with 100-ms silent intervals) rather than only once, suggesting that limits on attention switching do not underlie the duration effect. However, performance improved in some conditions when four successive 50-ms segments were extracted from the 200-ms double vowels and presented in sequence, again with 100-ms silent intervals. Similar improvements were observed in experiment 2 between performance with the first 50-ms segment and one or more of the other three segments when the segments were presented individually. Experiment 3 demonstrated that part of the improvement observed in experiments 1 and 2 could be attributed to waveform interactions that either reinforce or attenuate harmonics that lie near vowel formants. Such interactions were beneficial only when the difference in F0 was small (0.25-1 semitone). These results are compatible with the idea that listeners benefit from small differences in F0 by performing a sequence of analyses of different time segments of a double vowel to determine where the formants of the constituent vowels are best defined.

Flightin maintains myofilament lattice organization required for optimal flight power and courtship song quality in Drosophila.

PubMed

Chakravorty, Samya; Tanner, Bertrand C W; Foelber, Veronica Lee; Vu, Hien; Rosenthal, Matthew; Ruiz, Teresa; Vigoreaux, Jim O

2017-05-17

The indirect flight muscles (IFMs) of Drosophila and other insects with asynchronous flight muscles are characterized by a crystalline myofilament lattice structure. The high-order lattice regularity is considered an adaptation for enhanced power output, but supporting evidence for this claim is lacking. We show that IFMs from transgenic flies expressing flightin with a deletion of its poorly conserved N-terminal domain ( fln ΔN62 ) have reduced inter-thick filament spacing and a less regular lattice. This resulted in a decrease in flight ability by 33% and in skinned fibre oscillatory power output by 57%, but had no effect on wingbeat frequency or frequency of maximum power output, suggesting that the underlying actomyosin kinetics is not affected and that the flight impairment arises from deficits in force transmission. Moreover, we show that fln ΔN62 males produced an abnormal courtship song characterized by a higher sine song frequency and a pulse song with longer pulses and longer inter-pulse intervals (IPIs), the latter implicated in male reproductive success. When presented with a choice, wild-type females chose control males over mutant males in 92% of the competition events. These results demonstrate that flightin N-terminal domain is required for optimal myofilament lattice regularity and IFM activity, enabling powered flight and courtship song production. As the courtship song is subject to female choice, we propose that the low amino acid sequence conservation of the N-terminal domain reflects its role in fine-tuning species-specific courtship songs. © 2017 The Author(s).

Interventional repetitive I-wave transcranial magnetic stimulation (TMS): the dimension of stimulation duration.

PubMed

Murray, Lynda M; Nosaka, Kazunori; Thickbroom, Gary W

2011-10-01

A range of transcranial magnetic stimulation (TMS) techniques are now available to modulate human corticomotor excitability and plasticity. One presumably critical aspect of these interventions is their duration of application. In the current study, we investigated whether doubling the duration of an intervention would offer any additional benefit, or invoke self-limiting mechanisms controlling corticomotor excitability or synaptic plasticity. We compared (in a cross-over design) corticomotor excitability (to the first dorsal interosseous muscle) during and after a 15-minute (I15) and 30-minute (I30) TMS intervention targeting indirect (I-) wave interaction (iTMS). The interventions consisted of equi-intensity paired stimuli with an interpulse interval (IPI) of 1.5 milliseconds, corresponding to I-wave periodicity, delivered at a frequency of 0.2 Hz. During both the I15 and I30 interventions, paired-pulse (I-wave) motor evoked potential (iMEP) amplitude significantly increased (by 98.3% and 120.6%, respectively, last versus first minute, P = .001). The increase for I30 occurred in the first 15 minutes, and there was no further change during the remainder of the intervention. Both interventions were equally effective overall. Postintervention, single-pulse MEP amplitude increased by a mean of 91% and 106% (I15 and I30, respectively, P < .01) with no significant difference between interventions. We conclude that repetitive iTMS can increase corticomotor excitability after a relatively short intervention period of stimulation, and that a longer stimulation period has no additional benefit or detriment, perhaps as a result of the action of regulatory mechanisms. Copyright © 2011 Elsevier Inc. All rights reserved.

Metabolic syndrome and C-reactive protein in bank employees.

PubMed

Cattafesta, Monica; Bissoli, Nazaré Souza; Salaroli, Luciane Bresciani

2016-01-01

The ultrasensitive C-reactive protein (us-CRP) is used for the diagnosis of cardiovascular disease, but it is not well described as a marker for the diagnosis of metabolic syndrome (MS). An observational and transversal study of bank employees evaluated anthropometric, hemodynamic, and biochemical data. CRP values were determined using commercial kits from Roche Diagnostics Ltd, and MS criteria were analyzed according to National Cholesterol Education Program's - Adult Treatment Panel III (NCEP/ATP III). A total of 88 individuals had MS, and 77.3% (n=68) of these showed alterations of us-CRP (P=0.0001, confidence interval [CI] 0.11-0.34). Individuals with MS had higher mean values of us-CRP in global measures (P=0.0001) and stratified by sex (P=0.004) than individuals without the syndrome. This marker exhibited significant differences with varying criteria for MS, such as waist circumference (P=0.0001), triglycerides (P=0.002), and diastolic blood pressure (P=0.007), and the highest levels of us-CRP were found in individuals with more MS criteria. us-CRP was strongly associated with the presence of MS and MS criteria in this group of workers. us-CRP is a useful and effective marker for identifying the development of MS and may be used as a reference in routine care.

Magnitude of increase in QTc interval after initiation of dofetilide in patients with persistent atrial fibrillation is associated with increased rates of pharmacological cardioversion and long-term freedom from recurrent atrial fibrillation.

PubMed

Huang, Henry D; Waks, Jonathan W; Steinhaus, Daniel A; Zimetbaum, Peter

2016-07-01

Dofetilide is a class III antiarrhythmic drug approved for the treatment of atrial fibrillation (AF). Dofetilide-induced corrected QT (QTc) interval prolongation is a surrogate for the degree of drug effect, but the relationships between drug-induced QTc interval prolongation, pharmacological cardioversion (PCV), and freedom from recurrent AF are unclear. The purpose of this study was to assess associations between QTc interval change during dofetilide initiation and PCV and long-term AF recurrence. We performed retrospective analyses of a prospective cohort of patients with AF admitted for dofetilide initiation between 2001 and 2014. Clinical characteristics and electrocardiographic variables were assessed. We evaluated outcomes of successful PCV in patients with persistent AF and time to recurrence of AF in patients with paroxysmal and persistent AF. During the study, 243 patients with persistent AF and 176 patients with paroxysmal AF initiated dofetilide. PCV occurred in 93/243 (41.7%) patients with persistent AF. After multivariable adjustment, QTc interval change was associated with PCV (adjusted odds ratio 1.21; P = .003 per 10-ms QTc increase). Inhospital QTc interval change was associated with long-term freedom from AF in patients with persistent AF (adjusted hazard ratio 0.92; P = .011 at 4 years per 10-ms QTc increase), but not in patients with paroxysmal AF. In patients with persistent AF, PCV was also associated with long-term freedom from recurrent AF (adjusted hazard ratio 0.62; P = .009 at 4 years). The magnitude of QTc interval prolongation during dofetilide initiation is an independent predictor of successful PCV and long-term freedom from arrhythmia in patients with persistent AF. QTc interval change had no association with AF recurrence in patients with paroxysmal AF, suggesting that different mechanisms of arrhythmogenesis may be operant in different AF types. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

The effects of interstimulus interval on event-related indices of attention: an auditory selective attention test of perceptual load theory.

PubMed

Gomes, Hilary; Barrett, Sophia; Duff, Martin; Barnhardt, Jack; Ritter, Walter

2008-03-01

We examined the impact of perceptual load by manipulating interstimulus interval (ISI) in two auditory selective attention studies that varied in the difficulty of the target discrimination. In the paradigm, channels were separated by frequency and target/deviant tones were softer in intensity. Three ISI conditions were presented: fast (300ms), medium (600ms) and slow (900ms). Behavioral (accuracy and RT) and electrophysiological measures (Nd, P3b) were observed. In both studies, participants evidenced poorer accuracy during the fast ISI condition than the slow suggesting that ISI impacted task difficulty. However, none of the three measures of processing examined, Nd amplitude, P3b amplitude elicited by unattended deviant stimuli, or false alarms to unattended deviants, were impacted by ISI in the manner predicted by perceptual load theory. The prediction based on perceptual load theory, that there would be more processing of irrelevant stimuli under conditions of low as compared to high perceptual load, was not supported in these auditory studies. Task difficulty/perceptual load impacts the processing of irrelevant stimuli in the auditory modality differently than predicted by perceptual load theory, and perhaps differently than in the visual modality.

Simultaneous determination of radionuclides separable into natural decay series by use of time-interval analysis.

PubMed

Hashimoto, Tetsuo; Sanada, Yukihisa; Uezu, Yasuhiro

2004-05-01

A delayed coincidence method, time-interval analysis (TIA), has been applied to successive alpha- alpha decay events on the millisecond time-scale. Such decay events are part of the (220)Rn-->(216)Po ( T(1/2) 145 ms) (Th-series) and (219)Rn-->(215)Po ( T(1/2) 1.78 ms) (Ac-series). By using TIA in addition to measurement of (226)Ra (U-series) from alpha-spectrometry by liquid scintillation counting (LSC), two natural decay series could be identified and separated. The TIA detection efficiency was improved by using the pulse-shape discrimination technique (PSD) to reject beta-pulses, by solvent extraction of Ra combined with simple chemical separation, and by purging the scintillation solution with dry N(2) gas. The U- and Th-series together with the Ac-series were determined, respectively, from alpha spectra and TIA carried out immediately after Ra-extraction. Using the (221)Fr-->(217)At ( T(1/2) 32.3 ms) decay process as a tracer, overall yields were estimated from application of TIA to the (225)Ra (Np-decay series) at the time of maximum growth. The present method has proven useful for simultaneous determination of three radioactive decay series in environmental samples.

Depressed heart rate variability as an independent predictor of death in chronic congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

PubMed

Ponikowski, P; Anker, S D; Chua, T P; Szelemej, R; Piepoli, M; Adamopoulos, S; Webb-Peploe, K; Harrington, D; Banasiak, W; Wrabec, K; Coats, A J

1997-06-15

After acute myocardial infarction, depressed heart rate variability (HRV) has been proven to be a powerful independent predictor of a poor outcome. Although patients with chronic congestive heart failure (CHF) have also markedly impaired HRV, the prognostic value of HRV analysis in these patients remains unknown. The aim of this study was to investigate whether HRV parameters could predict survival in 102 consecutive patients with moderate to severe CHF (90 men, mean age 58 years, New York Heart Association [NYHA] class II to IV, CHF due to idiopathic dilated cardiomyopathy in 24 patients and ischemic heart disease in 78 patients, ejection fraction [EF], 26%; peak oxygen consumption, 16.9 ml/kg/min) after exclusion of patients in atrial fibrilation with diabetes or with chronic renal failure. In the prognostic analysis (Cox proportional-hazards model, Kaplan-Meier survival analysis), the following factors were investigated: age, CHF etiology, NYHA class, EF, peak oxygen consumption, presence of ventricular tachycardia on Holter monitoring, and HRV measures derived from 24-hour electrocardiography monitoring, calculated in the time (standard deviation of all normal RR intervals [SDNN], standard deviation of 5-minute RR intervals [SDANN], mean of all 5-minute standard deviations of RR intervals [SD], root-mean-square of difference of successive RR intervals [rMSSD], and percentage of adjacent RR intervals >50 ms different [pNN50]) and frequency domain (total power [TP], power within low-frequency band [LF], and power within high-frequency band [HF]). During follow-up of 584 +/- 405 days (365 days in all who survived), 19 patients (19%) died (mean time to death: 307 +/- 315 days, range 3 to 989). Cox's univariate analysis identified the following factors to be predictors of death: NYHA (p = 0.003), peak oxygen consumption (p = 0.01), EF (p = 0.02), ventricular tachycardia on Holter monitoring (p = 0.05), and among HRV measures: SDNN (p = 0.004), SDANN (p = 0.003), SD (p = 0.02), and LF (p = 0.003). In multivariate analysis, HRV parameters (SDNN, SDANN, LF) were found to predict survival independently of NYHA functional class, EF, peak oxygen consumption, and ventricular tachycardia on Holter monitoring. The Kaplan-Meier survival curves revealed SDNN < 100 ms to be a useful risk factor; 1-year survival in patients with SDNN < 100 ms was 78% when compared with 95% in those with SDNN > 100 ms (p = 0.008). The coexistence of SDNN < 100 ms and a peak oxygen consumption < 14 ml/kg/min allowed identification of a group of 18 patients with a particularly poor prognosis (1-year survival 63% vs 94% in the remaining patients, p <0.001). We conclude that depressed HRV on 24-hour ambulatory electrocardiography monitoring is an independent risk factor for a poor prognosis in patients with CHF. Whether analysis of HRV could be recommended in the risk stratification for better management of patients with CHF needs further investigation.

LC-MS/MS imaging with thermal film-based laser microdissection.

PubMed

Oya, Michiko; Suzuki, Hiromi; Anas, Andrea Roxanne J; Oishi, Koichi; Ono, Kenji; Yamaguchi, Shun; Eguchi, Megumi; Sawada, Makoto

2018-01-01

Mass spectrometry (MS) imaging is a useful tool for direct and simultaneous visualization of specific molecules. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used to evaluate the abundance of molecules in tissues using sample homogenates. To date, however, LC-MS/MS has not been utilized as an imaging tool because spatial information is lost during sample preparation. Here we report a new approach for LC-MS/MS imaging using a thermal film-based laser microdissection (LMD) technique. To isolate tissue spots, our LMD system uses a 808-nm near infrared laser, the diameter of which can be freely changed from 2.7 to 500 μm; for imaging purposes in this study, the diameter was fixed at 40 μm, allowing acquisition of LC-MS/MS images at a 40-μm resolution. The isolated spots are arranged on a thermal film at 4.5-mm intervals, corresponding to the well spacing on a 384-well plate. Each tissue spot is handled on the film in such a manner as to maintain its spatial information, allowing it to be extracted separately in its individual well. Using analytical LC-MS/MS in combination with the spatial information of each sample, we can reconstruct LC-MS/MS images. With this imaging technique, we successfully obtained the distributions of pilocarpine, glutamate, γ-aminobutyric acid, acetylcholine, and choline in a cross-section of mouse hippocampus. The protocol we established in this study is applicable to revealing the neurochemistry of pilocarpine model of epilepsy. Our system has a wide range of uses in fields such as biology, pharmacology, pathology, and neuroscience. Graphical abstract Schematic Indication of LMD-LC-MS/MS imaging.

Discovery of 4ms and 7 MS Pulsars in M15 (F & H)

NASA Astrophysics Data System (ADS)

Middleditch, J.

1992-12-01

Observations of M15 taken during Oct. 23-Nov. 1 1991 with the Arecibo 305-m telescope at 430 MHz, which were analyzed using 2-billion point Fourier transforms on supercomputers at Los Alamos National Laboratory, reveal two new ms pulsars in the globular cluster, M15. The sixth and fastest yet discovered in this cluster, M15F, has a spin rate of 248.3 Hz, while the eighth and latest to be discovered in this cluster has a spin rate of 148.3 Hz, the only one known so far in the frequency interval of 100-200 Hz. Further details and implications of these discoveries will be discussed.

The sodium glucose cotransporter 2 inhibitor empagliflozin does not prolong QT interval in a thorough QT (TQT) study

PubMed Central

2013-01-01

Background Empagliflozin is a potent, selective sodium glucose cotransporter 2 (SGLT2) inhibitor in development as an oral antidiabetic treatment. This QT interval study assessed potential effects of empagliflozin on ventricular repolarisation and other electrocardiogram (ECG) parameters. Methods A randomised, placebo-controlled, single-dose, double-blind, five-period crossover study incorporating a novel double-placebo period design to reduce sample size, while maintaining full statistical power. Treatments: single empagliflozin doses of 25 mg (therapeutic) and 200 mg (supratherapeutic), matching placebo and open-label moxifloxacin 400 mg (positive control). Triplicate 12-lead ECGs of 10 second duration were recorded at baseline and during the first 24 hours after dosing. The primary endpoint was mean change from baseline (MCfB) in the population heart rate-corrected QT interval (QTcN) between 1–4 hours after dosing. Results Thirty volunteers (16 male, 14 female, mean [range] age: 34.5 [18–52] years) were randomised. The placebo-corrected MCfB in QTcN 1–4 hours after dosing was 0.6 (90% CI: -0.7, 1.9) ms and -0.2 (-1.4, 0.9) ms for empagliflozin 25 mg and 200 mg, respectively, below the ICH E14 defined threshold of regulatory concern 10 ms. Assay sensitivity was confirmed by a placebo-corrected MCfB in QTcN 2–4 hours post-dose of 12.4 (10.7, 14.1) ms with moxifloxacin 400 mg. Empagliflozin tolerability was good for all volunteers; 23.3% experienced adverse events (AEs) with empagliflozin and 27.6% with placebo. The most frequent AE was nasopharyngitis. Conclusions/interpretation Single doses of empagliflozin 25 mg and 200 mg were not associated with QTcN prolongation and were well tolerated in healthy volunteers. Trial registration ClinicalTrials.gov: NCT01195675 PMID:23617452

Intravenous sotalol decreases transthoracic cardioversion energy requirement for chronic atrial fibrillation in humans: assessment of the electrophysiological effects by biatrial basket electrodes.

PubMed

Lai, L P; Lin, J L; Lien, W P; Tseng, Y Z; Huang, S K

2000-05-01

This study was undertaken to assess the effects of sotalol on the transthoracic cardioversion energy requirement for chronic atrial fibrillation (AF) and on the atrial electrograms during AF recorded by two basket electrodes. The effects of sotalol infusion on transthoracic electrical cardioversion for chronic atrial fibrillation in humans have not been well investigated. We included 18 patients with persistent AF for more than three months. Atrial electrograms were recorded by two basket electrodes positioned in each atrium respectively. Transthoracic cardioversion was performed before and after sotalol 1.5 mg/kg i.v. infusion. In the 14 patients whose AF could be terminated by cardioversion before sotalol infusion, the atrial defibrillation energy was significantly reduced after sotalol infusion (236 +/- 74 jules [J] vs. 186 +/- 77 J; p < 0.01). Atrial fibrillation was refractory to cardioversion in four patients at baseline and was converted to sinus rhythm by cardioversion after sotalol infusion in two of them. We further divided the patients into two groups. Group A consisted of 10 patients in whom the energy requirement was decreased by sotalol while group B consisted of eight patients in whom the energy requirement was not decreased. The mean A-A (atrial local electrogram) intervals during AF were significantly increased after sotalol infusion in both groups, but the increment of A-A interval was significantly larger in group A than it was in group B patients (36 +/- 13 ms vs. 22 +/- 8 ms for the right atrium; 19 +/- 7 ms vs. 9 +/- 7 ms for the left atrium; both p < 0.05). The spatial and temporal dispersions of A-A intervals were not significantly changed after sotalol infusion in both atria in both groups. Sotalol decreases the atrial defibrillation energy requirement by increasing atrial refractoriness but not by decreasing the dispersion of refractoriness.

Normal standards for computer-ECG programs for prognostically and diagnostically important ECG variables derived from a large ethnically diverse female cohort: the Women's Health Initiative (WHI).

PubMed

Rautaharju, Pentti M; Zhang, Zhu-ming; Gregg, Richard E; Haisty, Wesley K; Z Vitolins, Mara; Curtis, Anne B; Warren, James; Horaĉek, Milan B; Zhou, Sophia H; Soliman, Elsayed Z

2013-01-01

Substantial new information has emerged recently about the prognostic value for a variety of new ECG variables. The objective of the present study was to establish reference standards for these novel risk predictors in a large, ethnically diverse cohort of healthy women from the Women's Health Initiative (WHI) study. The study population consisted of 36,299 healthy women. Racial differences in rate-adjusted QT end (QT(ea)) and QT peak (QT(pa)) intervals as linear functions of RR were small, leading to the conclusion that 450 and 390 ms are applicable as thresholds for prolonged and shortened QT(ea) and similarly, 365 and 295 ms for prolonged and shortened QT(pa), respectively. As a threshold for increased dispersion of global repolarization (T(peak)T(end) interval), 110 ms was established for white and Hispanic women and 120 ms for African-American and Asian women. ST elevation and depression values for the monitoring leads of each person with limb electrodes at Mason-Likar positions and chest leads at level of V1 and V2 were first computed from standard leads using lead transformation coefficients derived from 892 body surface maps, and subsequently normal standards were determined for the monitoring leads, including vessel-specific bipolar left anterior descending, left circumflex artery and right coronary artery leads. The results support the choice 150 μV as a tentative threshold for abnormal ST-onset elevation for all monitoring leads. Body mass index (BMI) had a profound effect on Cornell voltage and Sokolow-Lyon voltage in all racial groups and their utility for left ventricular hypertrophy classification remains open. Common thresholds for all racial groups are applicable for QT(ea), and QT(pa) intervals and ST elevation. Race-specific normal standards are required for many other ECG parameters. Copyright © 2013 Elsevier Inc. All rights reserved.

Explosive Strength of the Knee Extensors: The Influence of Criterion Trial Detection Methodology on Measurement Reproducibility

PubMed Central

Wiesinger, Hans-Peter; Wiemer, Nicolas; Kösters, Alexander; Müller, Erich

2016-01-01

Abstract The present study was conducted to assess test-retest reproducibility of explosive strength measurements during single-joint isometric knee extension using the IsoMed 2000 dynamometer. Thirty-one physically active male subjects (mean age: 23.7 years) were measured on two occasions separated by 48–72 h. The intraclass correlation coefficient (ICC 2,1) and the coefficient of variation (CV) were calculated for (i) maximum torque (MVC), (ii) the peak rate of torque development (RTDpeak) as well as for (iii) the average rate of torque development (RTD) and the impulse taken at several predefined time intervals (0–30 to 0–300 ms); thereby explosive strength variables were derived in two conceptually different versions: on the one hand from the MVC-trial (version I), on the other hand from the trial showing the RTDpeak (version II). High ICC-values (0.80–0.99) and acceptable CV-values (1.9–8.7%) could be found for MVC as well as for the RTD and the impulse taken at time intervals of ≥100 ms, regardless of whether version I or II was used. In contrast, measurements of the RTDpeak as well as the RTD and the impulse taken during the very early contraction phase (i.e. RTD/impulse0–30ms and RTD/impulse0–50ms) showed clearly weaker reproducibility results (ICC: 0.53–0.84; CV: 7.3–16.4%) and gave rise to considerable doubts as to clinical usefulness, especially when derived using version I. However, if there is a need to measure explosive strength for earlier time intervals in practice, it is, in view of stronger reproducibility results, recommended to concentrate on measures derived from version II, which is based on the RTDpeak-trial. PMID:28149337

Electrocardiographic measures of repolarization dispersion and their relationships with echocardiographic indices of ventricular remodeling and premature ventricular beats in hypertension

PubMed Central

Ciobanu, Ana; Tse, Gary; Liu, Tong; Deaconu, Maria V; Gheorghe, Gabriela S; Ilieşiu, Adriana M; Nanea, Ioan T

2017-01-01

Objective To examine the relationship between Tpeak- Tend interval (Tpe) and Tpe/QT ratio with occurrence of ventricular premature beats (VPBs) and left ventricular remodeling in hypertension. Methods A total of 52 patients with mild to moderate essential hypertension were included, undergoing echocardiography and 24-hours Holter monitoring. Ventricular remodeling was assessed by left ventricular mass index (LVMI) using the Devereux formula and diastolic function by transmitral E and A wave velocities and E/A ratio. Tpe was measured in the precordial leads. The end of the T wave was set by the method of the tangent to the steepest descending slope of the T wave. Results Tpe and Tpe/QT in leads V2 (r = 0.33, P = 0.01; r = 0.27, P = 0.04 respectively) and V3 (r = 0.40, P = 0.002; r = 0.40, P = 0.003, respectively) correlated significantly with LVMI. A significant inverse relationship was observed between E/A ratio and QT (r = −0.33, P = 0.01), Tpe in V3 (r = −0.39, P = 0.003) and Tpe/QT in V3 (r = −0.31, P = 0.02). Tpe in V3, V5, mean Tpe and maximum Tpe with cut-off values of 60 ms, 59 ms, 62 ms and 71 ms, respectively, associated with the occurrence of ventricular premature beats. Conclusions The repolarization parameters Tpe interval and Tpe/QT ratio correlate with LVMI and indices of left ventricular diastolic function and show better predictive values than traditional parameters such as QT interval and QT dispersion. Lead V3 is the best lead for measuring Tpe and Tpe/QT. These ECG indices can therefore be used in clinical practice to monitor LV remodeling and predict occurrence of VPBs. PMID:29581710

Microvolt T-wave alternans and beat-to-beat variability of repolarization during early postischemic remodeling in a pig heart.

PubMed

Floré, Vincent; Claus, Piet; Antoons, Gudrun; Oosterhoff, Peter; Holemans, Patricia; Vos, Marc A; Sipido, Karin R; Willems, Rik

2011-07-01

Repolarization variability is considered to predict sudden cardiac death. T-wave alternans (TWA) has been the subject of exhaustive research, whereas beat-to-beat variability of repolarization (BVR) is a new parameter that possibly predicts proarrhythmia. How these parameters interact has not been tested. The purpose of this study was to compare TWA and BVR as predictors of proarrhythmic substrate early after myocardial infarction (MI). In nine pigs, MI was induced by 1-hour occlusion of the left anterior descending coronary artery. Cardiac magnetic resonance imaging was performed at day 21. Six sham pigs served as control. Spectral TWA was tested during right atrial pacing before induction of MI and after 21 days. BVR was calculated from 60 consecutive QT intervals. Magnetic resonance imaging showed transmural MI. TWA was negative in all pigs at clinical threshold rate and equally present in MI versus sham pigs at higher rates (170 bpm: 55% vs 50% positive TWA). In MI pigs, BVR of QT intervals increased significantly during acute ischemia (2.44 ± 0.43 ms vs 3.55 ± 0.41 ms, P <.01) and even more on day 21 (5.80 ± 1.12 ms), but it differed significantly from sham (2.14 ± 0.54 ms, P <.01). A clinical ventricular tachycardia induction protocol was positive in 2 of 8 MI pigs and in none of 6 shams. In early remodeling after MI, BVR at intrinsic heart rate was a consistent phenomenon, whereas TWA during atrial pacing or baseline QT-interval changes were not. TWA and BVR could reflect different post-MI remodeling processes. BVR may be a new technique for predicting a potentially proarrhythmic substrate in the early postinfarction period. Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Transformation of temporal sequences in the zebra finch auditory system

PubMed Central

Lim, Yoonseob; Lagoy, Ryan; Shinn-Cunningham, Barbara G; Gardner, Timothy J

2016-01-01

This study examines how temporally patterned stimuli are transformed as they propagate from primary to secondary zones in the thalamorecipient auditory pallium in zebra finches. Using a new class of synthetic click stimuli, we find a robust mapping from temporal sequences in the primary zone to distinct population vectors in secondary auditory areas. We tested whether songbirds could discriminate synthetic click sequences in an operant setup and found that a robust behavioral discrimination is present for click sequences composed of intervals ranging from 11 ms to 40 ms, but breaks down for stimuli composed of longer inter-click intervals. This work suggests that the analog of the songbird auditory cortex transforms temporal patterns to sequence-selective population responses or ‘spatial codes', and that these distinct population responses contribute to behavioral discrimination of temporally complex sounds. DOI: http://dx.doi.org/10.7554/eLife.18205.001 PMID:27897971

Significant variations in Weber fraction for changes in inter-onset interval of a click train over the range of intervals between 5 and 300 ms.

PubMed

Ungan, Pekcan; Yagcioglu, Suha

2014-01-01

It is a common psychophysical experience that a train of clicks faster than ca. 30/s is heard as one steady sound, whereas temporal patterns occurring on a slower time scale are perceptually resolved as individual auditory events. This phenomenon suggests the existence of two different neural mechanisms for processing of auditory sequences with fast and slow repetition rates. To test this hypothesis we used Weber's law, which is known to be valid for perception of time intervals. Discrimination thresholds and Weber fractions (WFs) for 12 base inter-click intervals (ICIs) between 5 and 300 ms were measured from 10 normal hearing subjects by using an "up-down staircase" algorithm. The mean WF, which is supposed to be constant for any perceptual mechanism according to Weber's law, displayed significant variation with click rate. WFs decreased sharply from an average value of around 5% at repetition rates below 20 Hz to about 0.5% at rates above 67 Hz. Parallel to this steep transition, subjects reported that at rates below 20 Hz they perceived periodicity as a fast tapping rhythm, whereas at rates above 50 Hz the perceived quality was a pitch. Such a dramatic change in WF indicated the existence of two separate mechanisms for processing the click rate for long and short ICIs, based on temporal and spectral features, respectively. A range of rates between 20 and 33 Hz, in which the rate discrimination threshold was maximum, appears to be a region where both of the presumed time and pitch mechanisms are relatively insensitive to rate alterations. Based on this finding, we speculate that the interval-based perception mechanism ceases to function at around 20 Hz and the spectrum-based mechanism takes over at around 33 Hz; leaving a transitional gap in between, where neither of the two mechanisms is as sensitive. Another notable finding was a significant drop in WF for ICI = 100 ms, suggesting a connection of time perception to the electroencephalography alpha rhythm.

Adipokines, insulin resistance, and adiposity as a predictors of metabolic syndrome in child survivors of lymphoma and acute lymphoblastic leukemia of a developing country.

PubMed

Barbosa-Cortés, Lourdes; López-Alarcón, Mardia; Mejía-Aranguré, Juan Manuel; Klünder-Klünder, Miguel; Del Carmen Rodríguez-Zepeda, María; Rivera-Márquez, Hugo; de la Vega-Martínez, Alan; Martin-Trejo, Jorge; Shum-Luis, Juan; Solis-Labastida, Karina; López-Aguilar, Enrique; Matute-González, Guadalupe; Bernaldez-Rios, Roberto

2017-02-13

There is a growing body of evidence indicating that pediatric survivors of cancer are at a greater risk of developing metabolic syndrome. This study evaluated some probable predictors of metabolic syndrome (MS), such as leptin and adiponectin concentrations, the leptin/adiponectin ratio, insulin resistance, and adiposity, in a sample of child survivors of lymphoma and leukemia in Mexico City. Fifty two children (leukemia n = 26, lymphoma n = 26), who were within the first 5 years after cessation of therapy, were considered as eligible to participate in the study. Testing included fasting insulin, glucose, adipokines and lipids; body fat mass was measured by DXA. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. Comparisons between continuous variables were performed according to the data distribution. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. With the purpose of assessing the risk of a present MS diagnosis, odds ratios (OR) with a 95% confidence interval (95% IC) were obtained using logistic regression analysis according to the various metabolic markers. The median children age was 12.1 years, and the interval time from the completion of therapy to study enrollment was 4 years. Among the MS components, the prevalence of HDL-C low was most common (42%), followed by central obesity (29%). The HOMA-IR (OR 9.0, 95% CI 2.0; 41.1), body fat (OR 5.5, 95% CI 1.6; 19.3), leptin level (OR 5.7, 95% CI 1.6; 20.2) and leptin/adiponectin ratio (OR 9.4, 95% CI 2.0; 49.8) in the highest tertile, were predictive factors of developing MS; whereas the lowest tertile of adiponectin was associated with a protective effect but not significant. Biomarkers such as HOMA-IR, leptin and leptin/adiponectin are associated with each of the components of the MS and with a heightened risk of suffering MS among children survivors of cancer. Given the close relationship between MS with risk of developing type 2 diabetes and cardiovascular disease, it is imperative to implement prevention measures in this population and especially in developing countries where these pathologies have become the leading cause of death.

The development of an MRI lesion quantifying system for multiple sclerosis patients undergoing treatment

NASA Astrophysics Data System (ADS)

Moin, Paymann; Ma, Kevin; Amezcua, Lilyana; Gertych, Arkadiusz; Liu, Brent

2009-02-01

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that affects approximately 2.5 million people worldwide. Magnetic resonance imaging (MRI) is an established tool for the assessment of disease activity, progression and response to treatment. The progression of the disease is variable and requires routine follow-up imaging studies. Currently, MRI quantification of multiple sclerosis requires a manual approach to lesion measurement and yields an estimate of lesion volume and interval change. In the setting of several prior studies and a long treatment history, trends related to treatment change quickly become difficult to extrapolate. Our efforts seek to develop an imaging informatics based MS lesion computer aided detection (CAD) package to quantify and track MS lesions including lesion load, volume, and location. Together, with select clinical parameters, this data will be incorporated into an MS specific e- Folder to provide decision support to evaluate and assess treatment options for MS in a manner tailored specifically to an individual based on trends in MS presentation and progression.

The effects of associative and semantic priming in the lexical decision task.

PubMed

Perea, Manuel; Rosa, Eva

2002-08-01

Four lexical decision experiments were conducted to examine under which conditions automatic semantic priming effects can be obtained. Experiments 1 and 2 analyzed associative/semantic effects at several very short stimulus-onset asynchronies (SOAs), whereas Experiments 3 and 4 used a single-presentation paradigm at two response-stimulus intervals (RSIs). Experiment 1 tested associatively related pairs from three semantic categories (synonyms, antonyms, and category coordinates). The results showed reliable associative priming effects at all SOAs. In addition, the correlation between associative strength and magnitude of priming was significant only at the shortest SOA (66 ms). When prime-target pairs were semantically but not associatively related (Experiment 2), reliable priming effects were obtained at SOAs of 83 ms and longer. Using the single-presentation paradigm with a short RSI (200 ms, Experiment 3), the priming effect was equal in size for associative + semantic and for semantic-only pairs (a 21-ms effect). When the RSI was set much longer (1,750 ms, Experiment 4), only the associative + semantic pairs showed a reliable priming effect (23 ms). The results are interpreted in the context of models of semantic memory.

Validating the Accuracy of Reaction Time Assessment on Computer-Based Tablet Devices.

PubMed

Schatz, Philip; Ybarra, Vincent; Leitner, Donald

2015-08-01

Computer-based assessment has evolved to tablet-based devices. Despite the availability of tablets and "apps," there is limited research validating their use. We documented timing delays between stimulus presentation and (simulated) touch response on iOS devices (3rd- and 4th-generation Apple iPads) and Android devices (Kindle Fire, Google Nexus, Samsung Galaxy) at response intervals of 100, 250, 500, and 1,000 milliseconds (ms). Results showed significantly greater timing error on Google Nexus and Samsung tablets (81-97 ms), than Kindle Fire and Apple iPads (27-33 ms). Within Apple devices, iOS 7 obtained significantly lower timing error than iOS 6. Simple reaction time (RT) trials (250 ms) on tablet devices represent 12% to 40% error (30-100 ms), depending on the device, which decreases considerably for choice RT trials (3-5% error at 1,000 ms). Results raise implications for using the same device for serial clinical assessment of RT using tablets, as well as the need for calibration of software and hardware. © The Author(s) 2015.

Reference intervals for plasma concentrations of adrenal steroids measured by LC-MS/MS: Impact of gender, age, oral contraceptives, body mass index and blood pressure status.

PubMed

Eisenhofer, Graeme; Peitzsch, Mirko; Kaden, Denise; Langton, Katharina; Pamporaki, Christina; Masjkur, Jimmy; Tsatsaronis, George; Mangelis, Anastasios; Williams, Tracy A; Reincke, Martin; Lenders, Jacques W M; Bornstein, Stefan R

2017-07-01

Mass spectrometric-based measurements of the steroid metabolome have been introduced to diagnose disorders featuring abnormal steroidogenesis. Defined reference intervals are important for interpreting such data. Liquid chromatography-tandem mass spectrometry was used to establish reference intervals for 16 steroids (pregnenolone, progesterone, 11-deoxycorticosterone, corticosterone, aldosterone, 18-oxocortisol, 18-hydroxycortisol, 17-hydroxyprogesterone, 21-deoxycortisol, 11-deoxycortisol, cortisol, cortisone, dehydroepiandrosterone, dehydroepiandrosterone-sulfate, androstenedione, testosterone) measured in plasma from 525 volunteers with (n=227) and without (n=298) hypertension, including 68 women on oral contraceptives. Women showed variable plasma concentrations of several steroids associated with menstrual cycle phase, menopause and oral contraceptive use. Progesterone was higher in females than males, but most other steroids were higher in males than females and almost all declined with advancing age. Using models that corrected for age and gender, body mass index showed weak negative relationships with corticosterone, 21-deoxycortisol, cortisol, cortisone, testosterone, progesterone, 17-hydroxyprogesterone and 11-deoxycorticosterone, but a positive relationship with 18-hydroxycortisol. Hypertensives and normotensives showed negligible differences in plasma concentrations of steroids. Age and gender are the most important variables for plasma steroid reference intervals, which have been established here according to those variables for a panel of 16 steroids primarily useful for diagnosis and subtyping of patients with endocrine hypertension. Copyright © 2017. Published by Elsevier B.V.

Age-related Differences in Pre- and Post-synaptic Motor Cortex Inhibition are Task Dependent.

PubMed

Opie, George M; Ridding, Michael C; Semmler, John G

2015-01-01

Previous research has shown age-related differences in short- (SICI) and long-interval intracortical inhibition (LICI) in both resting and active hand muscles, suggesting that healthy ageing influences post-synaptic motor cortex inhibition. However, it is not known how the ageing process effects the pre-synaptic interaction of SICI by LICI, and how these pre- and post-synaptic intracortical inhibitory circuits are modulated by the performance of different motor tasks in older adults. To examine age-related differences in pre- and post-synaptic motor cortex inhibition at rest, and during index finger abduction and precision grip. In 13 young (22.3 ± 3.8 years) and 15 old (73.7 ± 4.0 years) adults, paired-pulse transcranial magnetic stimulation (TMS) was used to measure SICI (2 ms inter-stimulus interval; ISI) and LICI (100 and 150 ms ISI), whereas triple-pulse TMS was used to investigate SICI when primed by LICI. We found no age-related difference in SICI at rest or during index finger abduction, but significantly greater SICI in older subjects during precision grip. Older adults showed reduced LICI in resting muscle (at an ISI of 150 ms), with no age-related differences in LICI during either task. When SICI was primed by LICI, disinhibition of motor cortex was reduced in older adults at rest (100 ms ISI) and during index finger abduction (150 ms ISI), but not during precision grip. Our results support age-related differences in pre- and post-synaptic motor cortex inhibition, which may contribute to impaired hand function during task performance in older adults. Copyright © 2015 Elsevier Inc. All rights reserved.

Pericardial Fat is Associated With Atrial Conduction: The Framingham Heart Study

PubMed Central

Friedman, Daniel J.; Wang, Na; Meigs, James B.; Hoffmann, Udo; Massaro, Joseph M.; Fox, Caroline S.; Magnani, Jared W.

2014-01-01

Background Obesity is associated with altered atrial electrophysiology and a prominent risk factor for atrial fibrillation. Body mass index, the most widely used adiposity measure, has been related to atrial electrical remodeling. We tested the hypothesis that pericardial fat is independently associated with electrocardiographic measures of atrial conduction. Methods and Results We performed a cross‐sectional analysis of 1946 Framingham Heart Study participants (45% women) to determine the relation between pericardial fat and atrial conduction as measured by P wave indices (PWI): PR interval, P wave duration (P‐duration), P wave amplitude (P‐amplitude), P wave area (P‐area), and P wave terminal force (P‐terminal). We performed sex‐stratified linear regression analyses adjusted for relevant clinical variables and ectopic fat depots. Each 1‐SD increase in pericardial fat was significantly associated with PR interval (β=1.7 ms, P=0.049), P‐duration (β=2.3 ms, P<0.001), and P‐terminal (β=297 μV·ms, P<0.001) among women; and P‐duration (β=1.2 ms, P=0.002), P‐amplitude (β=−2.5 μV, P<0. 001), and P‐terminal (β=160 μV·ms, P=0.002) among men. Among both sexes, pericardial fat was significantly associated with P‐duration in analyses additionally adjusting for visceral fat or intrathoracic fat; a similar but non‐significant trend existed with P‐terminal. Among women, pericardial fat was significantly associated with P wave area after adjustment for visceral and intrathoracic fat. Conclusions Pericardial fat is associated with atrial conduction as quantified by PWI, even with adjustment for extracardiac fat depots. Further studies are warranted to identify the mechanisms through which pericardial fat may modify atrial electrophysiology and promote subsequent risk for arrhythmogenesis. PMID:24595189

Clinically observed chickenpox and the risk of childhood-onset multiple sclerosis.

PubMed

Mikaeloff, Yann; Caridade, Guillaume; Suissa, Samy; Tardieu, Marc

2009-05-15

The authors conducted a population-based case-control study to investigate whether clinically observed chickenpox, linked with a level of intensity for clinical expression, increases the risk of multiple sclerosis (MS) in childhood. The cases were MS patients whose disease onset occurred between 1994 and 2003, before age 16 years, in France. Each case was matched for age, sex, and geographic origin with as many as 12 controls randomly selected from the general population. Information about clinically observed chickenpox in cases and controls before the index date regarding onset of MS was collected with a standardized questionnaire and was checked against health certificates. Conditional logistic regression was used to estimate the odds ratio for an association between MS and chickenpox. The 137 MS cases were matched with 1,061 controls. Clinically observed chickenpox had occurred in 76.6% of the cases and 84.9% of their matched controls. The adjusted odds ratio of MS onset associated with chickenpox occurrence was 0.58 (95% confidence interval: 0.36, 0.92). The authors concluded that clinically observed chickenpox was associated with a lower risk of childhood-onset MS in a French population.

An Updated Meta-Analysis of Risk of Multiple Sclerosis following Infectious Mononucleosis

PubMed Central

Handel, Adam E.; Williamson, Alexander J.; Disanto, Giulio; Handunnetthi, Lahiru; Giovannoni, Gavin; Ramagopalan, Sreeram V.

2010-01-01

Background Multiple sclerosis (MS) appears to develop in genetically susceptible individuals as a result of environmental exposures. Epstein-Barr virus (EBV) infection is an almost universal finding among individuals with MS. Symptomatic EBV infection as manifested by infectious mononucleosis (IM) has been shown in a previous meta-analysis to be associated with the risk of MS, however a number of much larger studies have since been published. Methods/Principal Findings We performed a Medline search to identify articles published since the original meta-analysis investigating MS risk following IM. A total of 18 articles were included in this study, including 19390 MS patients and 16007 controls. We calculated the relative risk of MS following IM using a generic inverse variance with random effects model. This showed that the risk of MS was strongly associated with IM (relative risk (RR) 2.17; 95% confidence interval 1.97–2.39; p<10−54). Discussion Our results establish firmly that a history of infectious mononucleosis significantly increases the risk of multiple sclerosis. Future work should focus on the mechanism of this association and interaction with other risk factors. PMID:20824132

On the Time Course of Vocal Emotion Recognition

PubMed Central

Pell, Marc D.; Kotz, Sonja A.

2011-01-01

How quickly do listeners recognize emotions from a speaker's voice, and does the time course for recognition vary by emotion type? To address these questions, we adapted the auditory gating paradigm to estimate how much vocal information is needed for listeners to categorize five basic emotions (anger, disgust, fear, sadness, happiness) and neutral utterances produced by male and female speakers of English. Semantically-anomalous pseudo-utterances (e.g., The rivix jolled the silling) conveying each emotion were divided into seven gate intervals according to the number of syllables that listeners heard from sentence onset. Participants (n = 48) judged the emotional meaning of stimuli presented at each gate duration interval, in a successive, blocked presentation format. Analyses looked at how recognition of each emotion evolves as an utterance unfolds and estimated the “identification point” for each emotion. Results showed that anger, sadness, fear, and neutral expressions are recognized more accurately at short gate intervals than happiness, and particularly disgust; however, as speech unfolds, recognition of happiness improves significantly towards the end of the utterance (and fear is recognized more accurately than other emotions). When the gate associated with the emotion identification point of each stimulus was calculated, data indicated that fear (M = 517 ms), sadness (M = 576 ms), and neutral (M = 510 ms) expressions were identified from shorter acoustic events than the other emotions. These data reveal differences in the underlying time course for conscious recognition of basic emotions from vocal expressions, which should be accounted for in studies of emotional speech processing. PMID:22087275

On the role of attention for the processing of emotions in speech: sex differences revisited.

PubMed

Schirmer, Annett; Kotz, Sonja A; Friederici, Angela D

2005-08-01

In a previous cross-modal priming study [A. Schirmer, A.S. Kotz, A.D. Friederici, Sex differentiates the role of emotional prosody during word processing, Cogn. Brain Res. 14 (2002) 228-233.], we found that women integrated emotional prosody and word valence earlier than men. Both sexes showed a smaller N400 in the event-related potential to emotional words when these words were preceded by a sentence with congruous compared to incongruous emotional prosody. However, women showed this effect with a 200-ms interval between prime sentence and target word whereas men showed the effect with a 750-ms interval. The present study was designed to determine whether these sex differences prevail when attention is directed towards the emotional content of prosody and word meaning. To this end, we presented the same prime sentences and target words as in our previous study. Sentences were spoken with happy or sad prosody and followed by a congruous or incongruous emotional word or pseudoword. The interval between sentence offset and target onset was 200 ms. In addition to performing a lexical decision, participants were asked to decide whether or not a word matched the emotional prosody of the preceding sentence. The combined lexical and congruence judgment failed to reveal differences in emotional-prosodic priming between men and women. Both sexes showed smaller N400 amplitudes to emotionally congruent compared to incongruent words. This suggests that the presence of sex differences in emotional-prosodic priming depends on whether or not participants are instructed to take emotional prosody into account.

Validity of the Polar V800 monitor for measuring heart rate variability in mountain running route conditions.

PubMed

Caminal, Pere; Sola, Fuensanta; Gomis, Pedro; Guasch, Eduard; Perera, Alexandre; Soriano, Núria; Mont, Lluis

2018-03-01

This study was conducted to test, in mountain running route conditions, the accuracy of the Polar V800™ monitor as a suitable device for monitoring the heart rate variability (HRV) of runners. Eighteen healthy subjects ran a route that included a range of running slopes such as those encountered in trail and ultra-trail races. The comparative study of a V800 and a Holter SEER 12 ECG Recorder™ included the analysis of RR time series and short-term HRV analysis. A correction algorithm was designed to obtain the corrected Polar RR intervals. Six 5-min segments related to different running slopes were considered for each subject. The correlation between corrected V800 RR intervals and Holter RR intervals was very high (r = 0.99, p < 0.001), and the bias was less than 1 ms. The limits of agreement (LoA) obtained for SDNN and RMSSD were (- 0.25 to 0.32 ms) and (- 0.90 to 1.08 ms), respectively. The effect size (ES) obtained in the time domain HRV parameters was considered small (ES < 0.2). Frequency domain HRV parameters did not differ (p > 0.05) and were well correlated (r ≥ 0.96, p < 0.001). Narrow limits of agreement, high correlations and small effect size suggest that the Polar V800 is a valid tool for the analysis of heart rate variability in athletes while running high endurance events such as marathon, trail, and ultra-trail races.

Reduced Baroreflex Sensitivity in Cluster Headache Patients.

PubMed

Barloese, Mads C J; Mehlsen, Jesper; Brinth, Louise; Lundberg, Helena I S; Jennum, Poul J; Jensen, Rigmor H

2015-06-01

Important elements of cluster headache (CH) pathophysiology may be seated in the posterior hypothalamus. Cranial autonomic features are inherent, but involvement of systemic autonomic control is still debated. We aimed to characterize autonomic function as investigated by baroreflex sensitivity (BRS) in CH patients. Twenty-six active CH patients and an equal number of age-, sex-, and BMI-matched controls underwent head-up tilt table test and BRS was determined by the sequence method. Compared with controls, patients exhibited a blunted reactivity of RR intervals in response to falls and increases in systolic blood pressure (SBP) (15.3 vs. 20.0 ms/mmHg, P = .0041) in the supine position. Also, compared with controls, BRS was lower in patients having suffered an attack within the past 12 hours (n = 13, 12.5 vs. 22.3 ms/mmHg, P = .0091), opposed to those patients who had not (n = 13, 16.0 ms/mmHg, P = .1523). In the tilted position, the drop in SBP at the carotid sinuses was higher in patients who had recently suffered an attack. Despite this, they exhibited a less marked shortening of RR intervals when compared with patients who had been attack free for longer. CH patients exhibit a subclinical blunting of BRS that may be affected by the attacks themselves. The fast RR interval fluctuations used in this method reflects cardiovagal responses, thus the blunted responses are suggestive of dysfunction in the parasympathetic division of the autonomic nervous system or in the central relay of impulses from the baroreceptors. © 2015 American Headache Society.

The relationship between atrial electromechanical delay and left atrial mechanical function in stroke patients

PubMed Central

Akıl, Mehmet Ata; Akıl, Eşref; Bilik, Mehmet Zihni; Oylumlu, Mustafa; Acet, Halit; Yıldız, Abdülkadir; Akyüz, Abdurrahman; Ertaş, Faruk; Toprak, Nizamettin

2015-01-01

Objective: The aim of this study was to evaluate the relationship between atrial electromechanical delay (EMD) measured with tissue Doppler imaging (TDI) and left atrial (LA) mechanical functions in patients with ischemic stroke and compare them with healthy controls. Methods: Thirty patients with ischemic stroke were enrolled into this cross-sectional, observational study. The control group consisted of 35 age- and gender-matched apparently healthy individuals patients. Acute cerebral infarcts of probable embolic origin were diagnosed via imaging and were confirmed by a neurologist. Echocardiographically, time intervals from the beginning of P wave to beginning of A wave from the lateral and septal mitral and right ventricular tricuspid annuli in TDI were recorded. The differences between these intervals gave the mechanical delays (inter- and intra-atrial). Left atrial (LA) volumes were measured using the biplane area-length method, and LA mechanical function parameters were calculated. Statistical analysis was performed using student’s t-test, chi-squared test, and Pearson’s test. Results: The laboratory and clinical characteristics were similar in the two groups. Increased left atrial EMD (21.36±10.38 ms versus 11.74±6.06 ms, p<0.001), right atrial EMD (13.66±8.62 ms versus 9.66±6.81 ms, p=0.040), and interatrial EMD (35.03±9.95 ms versus 21.40±8.47 ms, p<0.001) were observed in stroke patients as compared to controls. Active LA emptying volume and fraction and passive LA emptying volumes and fraction were similar between controls and stroke patients. Total LA emptying volumes were significantly increased in stroke patients as compared to healthy controls (33.19±11.99 mL/m2 versus 27.48±7.08 mL/m2, p=0.021). Conclusion: According to the results of our study, interatrial electromechanical delay may be a new predictor for ischemic stroke. PMID:25537998

[The characteristics of VEMP in patients with acoustic neuroma].

PubMed

Xue, Bin; Yang, Jun

2008-01-01

To establish the normal value of the vestibular evoked myogenic potential (VEMP), and to determine the characteristics of VEMP in patients with acoustic neuroma (AN) and to explore the significance of VEMP in diagnosis of AN. Click-evoked VEMP was recorded with surface electrodes attached on the sternocleidomastoid muscle. Latencies and amplitudes of specific waveform of VEMP were measured. The hearing normal subjects including 26 males and 20 females were chosen to establish the normal value of VEMP. VEMP was investigated in 14 patients with AN who underwent surgery during the period of 2006-2007 as well as auditory brainstem response (ABR) and vestibular caloric test. Of 46 subjects with normal hearing, VEMP was present in both ears in 43 subjects, absent in either ear in three subjects. The reducible rate is 93.5% (86/92). The nor-mal value obtained from 86 reducible ears were as follows (means +/- standard deviation): latency of p13 (11.86 +/- 2.11) ms, latency of n23 (18.57 +/- 2.19) ms, interval time between p13 and n23 (6.71 +/- 1.69) ms, amplitude of p13n23 (24.18 +/- 8.22) microV. Interaural variances in 43 subjects whose VEMP were available were as follows (means +/- standard deviation): /deltap13 (0.64 +/- 0.61) ms, /deltan23/(1.05 +/- 0.97) ms, interval time between /delta13n23/ (0.84 +/- 0.81) ms, amplitude ratio (max/min) 1.32 +/- 0. 37, interaural asymmetric ratio of VEMP 0.12 +/- 0.11. Of the 14 patients with AN, VEMP was absent on the affected side in eight patients, absent on either side in three patients, and present on the unaffected side in 11 patients. VEMP presented on the affected side in three patients was significantly prolonged in /deltapl3/ and /deltap13n23/. Patients with AN characterized with VEMP could be useful in the diagnosis of AN combined together with other tests.

Gait Speed Predicts 30-Day Mortality After Transcatheter Aortic Valve Replacement: Results From the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry.

PubMed

Alfredsson, Joakim; Stebbins, Amanda; Brennan, J Matthew; Matsouaka, Roland; Afilalo, Jonathan; Peterson, Eric D; Vemulapalli, Sreekanth; Rumsfeld, John S; Shahian, David; Mack, Michael J; Alexander, Karen P

2016-04-05

Surgical risk scores do not include frailty assessments (eg, gait speed), which are of particular importance for patients with severe aortic stenosis considering transcatheter aortic valve replacement. We assessed the association of 5-m gait speed with outcomes in a cohort of 8039 patients who underwent transcatheter aortic valve replacement (November 2011-June 2014) and were included in the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry. We evaluated the association between continuous and categorical gait speed and 30-day all-cause mortality before and after adjustment for Society of Thoracic Surgeons-predicted risk of mortality score and key variables. Secondary outcomes included in-hospital mortality, bleeding, acute kidney injury, and stroke. The overall median gait speed was 0.63 m/s (25th-75th percentile, 0.47-0.79 m/s), with the slowest walkers (<0.5 m/s) constituting 28%, slow walkers (0.5-0.83 m/s) making up 48%, and normal walkers (>0.83 m/s) constituting 24% of the population. Thirty-day all-cause mortality rates were 8.4%, 6.6%, and 5.4% for the slowest, slow, and normal walkers, respectively (P<0.001). Each 0.2-m/s decrease in gait speed corresponded to an 11% increase in 30-day mortality (adjusted odds ratio, 1.11; 95% confidence interval, 1.01-1.22). The slowest walkers had 35% higher 30-day mortality than normal walkers (adjusted odds ratio, 1.35; 95% confidence interval, 1.01-1.80), significantly longer hospital stays, and a lower probability of being discharged to home. Gait speed is independently associated with 30-day mortality after transcatheter aortic valve replacement. Identification of frail patients with the slowest gait speeds facilitates preprocedural evaluation and anticipation of a higher level of postprocedural care. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01737528. © 2016 American Heart Association, Inc.

Permanent pacemaker implantation in octogenarians with unexplained syncope and positive electrophysiologic testing.

PubMed

Giannopoulos, Georgios; Kossyvakis, Charalampos; Panagopoulou, Vasiliki; Tsiachris, Dimitrios; Doudoumis, Konstantinos; Mavri, Maria; Vrachatis, Dimitrios; Letsas, Konstantinos; Efremidis, Michael; Katsivas, Apostolos; Lekakis, John; Deftereos, Spyridon

2017-05-01

Syncope is a common problem in the elderly, and a permanent pacemaker is a therapeutic option when a bradycardic etiology is revealed. However, the benefit of pacing when no association of symptoms to bradycardia has been shown is not clear, especially in the elderly. The aim of this study was to evaluate the effect of pacing on syncope-free mortality in patients aged 80 years or older with unexplained syncope and "positive" invasive electrophysiologic testing (EPT). This was an observational study. A positive EPT for the purposes of this study was defined by at least 1 of the following: a corrected sinus node recovery time of >525 ms, a basic HV interval of >55 ms, detection of infra-Hisian block, or appearance of second-degree atrioventricular block on atrial decremental pacing at a paced cycle length of >400 ms. Among the 2435 screened patients, 228 eligible patients were identified, 145 of whom were implanted with a pacemaker. Kaplan-Meier analysis determined that time to event (syncope or death) was 50.1 months (95% confidence interval 45.4-54.8 months) with a pacemaker vs 37.8 months (95% confidence interval 31.3-44.4 months) without a pacemaker (log-rank test, P = .001). The 4-year time-dependent estimate of the rate of syncope was 12% vs 44% (P < .001) and that of any-cause death was 41% vs 56% (P = .023), respectively. The multivariable odds ratio was 0.25 (95% confidence interval 0.15-0.40) after adjustment for potential confounders. In patients with unexplained syncope and signs of sinus node dysfunction or impaired atrioventricular conduction on invasive EPT, pacemaker implantation was independently associated with longer syncope-free survival. Significant differences were also shown in the individual components of the primary outcome measure (syncope and death from any cause). Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Urinary iodine: comparison of a simple method for its determination in microplates with measurement by inductively-coupled plasma mass spectrometry

PubMed Central

Haap, Michael; Roth, Heinz Jürgen; Huber, Thomas; Dittmann, Helmut; Wahl, Richard

2017-01-01

The aim of our study was to develop and validate an inexpensive, rapid, easy to use quantitative method to determine urinary iodine without major procurement costs for equipment. The rationale behind introducing this method is the increasing demand for urinary iodine assessments. Our study included 103 patients (76 female, 27 male), age (arithmetic mean) 52 ± 17.3 years. Urinary iodine was determined in microplates by a modification of the Sandell-Kolthoff reaction. The results were compared with inductively-coupled plasma mass spectrometry (ICP-MS) for iodine, considered as reference method. Geometric mean of urinary iodine determined by the Sandell-Kolthoff reaction method was 62.69 μg/l (95% confidence interval 53.16–73.92) whereas by the ICP-MS method it was 65.53 μg/l (95% confidence interval 54.77–78.41). Passing-Bablok regression equations for both methods gave y = 3.374 + 0.873x (y: Sandell-Kolthoff method, x: ICP-MS). Spearman´s correlation coefficient was 0.981, indicating a very high degree of agreement between the two methods. Bland-Altman plots showed no significant systematic difference between the two methods. The modified Sandell-Kolthoff method using microtiter plate technique presented here is a simple, inexpensive semi-automated method to determine urinary iodine with very little toxic waste. Comparison with the ICP-MS-technique yielded a good agreement between the two methods. PMID:28045077

Aerobic interval exercise improves parameters of nonalcoholic fatty liver disease (NAFLD) and other alterations of metabolic syndrome in obese Zucker rats.

PubMed

Kapravelou, Garyfallia; Martínez, Rosario; Andrade, Ana M; Nebot, Elena; Camiletti-Moirón, Daniel; Aparicio, Virginia A; Lopez-Jurado, Maria; Aranda, Pilar; Arrebola, Francisco; Fernandez-Segura, Eduardo; Bermano, Giovanna; Goua, Marie; Galisteo, Milagros; Porres, Jesus M

2015-12-01

Metabolic syndrome (MS) is a group of metabolic alterations that increase the susceptibility to cardiovascular disease and type 2 diabetes. Nonalcoholic fatty liver disease has been described as the liver manifestation of MS. We aimed to test the beneficial effects of an aerobic interval training (AIT) protocol on different biochemical, microscopic, and functional liver alterations related to the MS in the experimental model of obese Zucker rat. Two groups of lean and obese animals (6 weeks old) followed a protocol of AIT (4 min at 65%-80% of maximal oxygen uptake, followed by 3 min at 50%-65% of maximal oxygen uptake for 45-60 min, 5 days/week, 8 weeks of experimental period), whereas 2 control groups remained sedentary. Obese rats had higher food intake and body weight (P < 0.0001) and suffered significant alterations in plasma lipid profile, area under the curve after oral glucose overload (P < 0.0001), liver histology and functionality, and antioxidant status. The AIT protocol reduced the severity of alterations related to glucose and lipid metabolism and increased the liver protein expression of PPARγ, as well as the gene expression of glutathione peroxidase 4 (P < 0.001). The training protocol also showed significant effects on the activity of hepatic antioxidant enzymes, although this action was greatly influenced by rat phenotype. The present data suggest that AIT protocol is a feasible strategy to improve some of the plasma and liver alterations featured by the MS.

Comparison of the docetaxel concentration in human plasma measured with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and a nanoparticle immunoassay and clinical applications of that assay.

PubMed

Geng, Chunmei; Li, Pingli; Chen, Xuwang; Yuan, Guiyan; Guo, Nan; Liu, Huanjun; Zhang, Rui; Guo, Ruichen

2017-05-23

To determine the feasibility of using a nanoparticle immunoassay for clinical therapeutic drug monitoring (TDM) of docetaxel concentrations, a sensitive and simple method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established to measure the docetaxel concentration in human plasma and the results of LC-MS/MS and the immunoassay were compared. Docetaxel and paclitaxel (the internal standard, or IS) in human plasma were extracted through protein precipitation, separated on a Diamonsil C18 column (150 mm × 4.6 mm, 5 μm), ionized with positive ions, and detected with LC-MS/MS in multi-reaction monitoring (MRM) mode. Plasma samples from 248 cancer patients were assayed with LC-MS/MS and a nanoparticle immunoassay. Data from the samples were analyzed with the statistical software SPSS and the software MedCalc. Results indicated that the calibration curve of the validated method of LC-MS/MS was linear over the range of 10-2,000 ng/mL, with an lowest limit of quantitation (LLOQ) of 10 ng/mL, and the intra- and inter- day precision and accuracy were both < ± 15%. Comparison of the two methods indicated that results of the LC-MS/MS were closely related to those of the nanoparticle immunoassay, with a correlation coefficient (R) of 0.965 and acceptable 95% confidence intervals (CI) of ‒ 231.7-331.1 ng/mL. Overall, the established method of LC-MC/MS and the nanoparticle immunoassay were both suitable for measurement of the docetaxel concentration in human plasma, and the immunoassay was far more cost-effective and better at clinical TDM of docetaxel in clinical practice.

Risk Factors for Permanent Pacemaker after Implantation of Surgical or Percutaneous Self-Expanding Aortic Prostheses.

PubMed

Villa, Emmanuel; Clerici, Alberto; Messina, Antonio; Testa, Luca; Bedogni, Francesco; Moneta, Andrea; Donatelli, Francesco; Troise, Giovanni

2016-11-01

The use of transcatheter aortic valve implantation (TAVI) following the introduction of Nitinol autoexpandable devices has spread rapidly during recent years. In addition, cardiac surgery has been revolutionized due to the use of Nitinol-based sutureless prostheses for aortic valve replacement (AVR). During the same period, however, permanent pacemaker (PPM) implantation has emerged as a frequent complication. The study aim was to identify the risk factors of PPM following the implantation of a Nitinol self-expanding prosthesis (for AVR or TAVI). A study group was created between two institutions experienced in the use of nitinol devices, and a pool of 336 patients (56.6% CoreValve - Medtronic; 43.4% Perceval - Sorin) was available for a retrospective analysis. Pre-procedural clinical and electrocardiography (ECG) variables and postprocedural ECG variables were compared between the PPM group and control patients who had not received a PPM during their index hospitalization. A PPM was required in 12.8% of patients (TAVI 17.5% versus AVR 6.8%, p = 0.007). PPM patients had a higher logistical EuroSCORE (median 20.77% versus 15.59%, p = 0.015), a lower use of statins (18.6% versus 34.2%, p = 0.04), a pre-procedural longer QRS interval (median 117 ms versus 98 ms, p = 0.002), and a higher incidence of conduction disturbances (29.3% versus 16.8%, p = 0.034), with a prevalence of right bundle branch block. At the first postprocedural ECG, non-stimulated PPM patients had a longer QRS interval (median 150 ms versus 113 ms, p<0.001) and a longer QTc interval (487.3 ± 46 ms versus 510.8 ± 53.8 ms, p = 0.005). Prevalent intra-ventricular conduction disorders in both groups included left bundle branch block. AVR patients received a PPM later than the TAVI group (median 6 days versus 3 days, p = 0.01). TAVI was an independent predictor of PPM at logistic regression analysis (OR 3.18; 95% CI 1.19-8.48, p = 0.021), but the significance disappeared after incorporating post-procedural ECG variables. Nitinol technology is a ground-breaking option for aortic valve procedures. However, the radial forces of the self-expandable mechanism may be implicated in the increased need for PPM, mostly in cases of TAVI compared to AVR, that most likely are due to displacement of the stent provoked by in situ calcium clusters. Given the clinical and economic impact of PPM, new parameters are required to understand the stent/tissue interaction and to help with device selection.

The effect of anesthetization and urinary bladder catheterization on renal function of rainbow trout

USGS Publications Warehouse

Hunn, J.B.; Willford, W.A.

1970-01-01

1. Rainbow trout were anesthetized with MS-222 (Sandoz) or methylpentynol and catheterized. Urine was collected at selected intervals up to 48 hr. 2. Effects of MS-222 anesthesia on urine flow and composition were isolated from the stress of catheterization by re-anesthetizing the fish 18 to 20 hr post catheterization. 3. Urine output patterns were similar following MS-222 or methylpentynol anesthesia and catheterization. Highest urine flows were measured 4 to 8 hr post treatment. The highest urine output after re-anesthetization with MS-222 was observed 2 to 4 hr post-anesthesia. 4. Highest concentrations of Na2+, K+, Ca2+, Cl- and inorganic PO4 in the urine were measured in the first 2 hr after anesthesia and catheterization. 5. Flow rates and chemical composition of urine indicate that "normal" renal function is re-established 12 to 24 hr post-treatment.

Metabolic syndrome and C-reactive protein in bank employees

PubMed Central

Cattafesta, Monica; Bissoli, Nazaré Souza; Salaroli, Luciane Bresciani

2016-01-01

Background The ultrasensitive C-reactive protein (us-CRP) is used for the diagnosis of cardiovascular disease, but it is not well described as a marker for the diagnosis of metabolic syndrome (MS). Methods An observational and transversal study of bank employees evaluated anthropometric, hemodynamic, and biochemical data. CRP values were determined using commercial kits from Roche Diagnostics Ltd, and MS criteria were analyzed according to National Cholesterol Education Program’s – Adult Treatment Panel III (NCEP/ATP III). Results A total of 88 individuals had MS, and 77.3% (n=68) of these showed alterations of us-CRP (P=0.0001, confidence interval [CI] 0.11–0.34). Individuals with MS had higher mean values of us-CRP in global measures (P=0.0001) and stratified by sex (P=0.004) than individuals without the syndrome. This marker exhibited significant differences with varying criteria for MS, such as waist circumference (P=0.0001), triglycerides (P=0.002), and diastolic blood pressure (P=0.007), and the highest levels of us-CRP were found in individuals with more MS criteria. Conclusion us-CRP was strongly associated with the presence of MS and MS criteria in this group of workers. us-CRP is a useful and effective marker for identifying the development of MS and may be used as a reference in routine care. PMID:27274294

High prevalence of sickness absence and disability pension among multiple sclerosis patients: a nationwide population-based study.

PubMed

Tinghög, Petter; Hillert, Jan; Kjeldgård, Linnea; Wiberg, Michael; Glaser, Anna; Alexanderson, Kristina

2013-12-01

Although multiple sclerosis (MS) often implies substantial disability, there is little knowledge about sick leave and disability pension among MS patients. The purpose of this study was to estimate the prevalence rates of sick leave and disability pension among MS patients and to explore how socio-demographics are associated with such rates. The register data of all people who lived in Sweden in 2005 and were 16-64 years old was used to identify 9721 MS patients and matched controls. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated and effect modifications were evaluated with Wald X(2) tests. In 2005, 61.7% of the MS patients were on partial or full disability pension compared to 14.2% among the controls. Of the others, 36.8% had ≥ 1 sick-leave spell for >14 days during that year. Socio-demographics were similarly associated with sick leave and disability pension among MS patients and controls, with the noteworthy exceptions that female gender and immigration status were less potent risk factors in the MS population (p<0.05). In spite of widespread access to modern health care including disease-modifying drugs, the majority of MS patients of working ages were on a disability pension. Strategies enabling MS patients to retain their footing in the labour market are needed.

[Influence of pacing site on myocardial transmural dispersion of repolarization in intact normal and dilated cardiomyopathy dogs].

PubMed

Bai, Rong; Pu, Jun; Liu, Nian; Lu, Jia-Gao; Zhou, Qiang; Ruan, Yan-Fei; Niu, Hui-Yan; Wang, Lin

2003-12-25

In order to verify the hypothesis that left ventricular epicardial (LV-Epi) pacing and biventricular (BiV) pacing unavoidably influence the myocardial electrophysiological characters and may result in high risk of malignant ventricular arrhythmia, we calculated, in both normal mongrel dogs and dog models with rapid-right-ventricular-pacing induced dilated cardiomyopathy congestive heart failure (DCM-CHF), the monophasic action potential duration (MAPD) and the transmural dispersion of repolarization (TDR) in intracardiac electrogram together with the QT interval and T(peak)-T(end) (T(p(-T(e)) interval in surface electrocardiogram (ECG) during LV-Epi and BiV pacing, compared with those during right ventricular endocardial (RV-Endo) pacing. To prepare the DCM-CHF dog model, rapid right ventricular pacing (250 bpm) was performed for 23.6+/-2.57 days to the dog. All the normal and DCM-CHF dogs were given radio frequency catheter ablation (RFCA) to His bundle with the guide of X-ray fluoroscopy. After the RFCA procedures, the animals were under the situation of complete atrioventricular block so that the canine heart rates could be voluntarily controlled in the following experiments. After a thoracotomy, ECG and monophasic action potentials (MAP) of subendocardial, subepicardial and mid-layer myocardium were recorded synchronously in 8 normal and 5 DCM-CHF dogs during pacing from endocardium of RV apex (RV-Endo), epicardium of LV anterior wall (LV-Epi) and simultaneously both of the above (biventricular, BiV), the later was similar to the ventricular resynchronization therapy to congestive heart failure patients in clinic. The Tp-Te) meant the interval from the peak to the end of T wave, which was a representative index of TDR in surface ECG. The TDR was defined as the difference between the longest and the shortest MAPD of subendocardial, subepicardial and mid-layer myocardium. Our results showed that in normal dogs, pacing participating of LV (LV-Epi, BiV) prolonged MAPD of all the three layers of the myocardium (P<0.05) with the character that mid-layer MAPD was the longest and subepicardial MAPD was the shortest following subendocardial MAPD. At the same time, TDR prolonged from 26.75 ms at RV-Endo pacing to 37.54 ms at BiV pacing and to 47.16 ms at LV-Epi pacing (P<0.001). Meanwhile in surface ECG, BiV and LV-Epi pacing resulted in a longer Tp-Te) interval compared with RV-Endo pacing (P<0.01), without parallel QT interval prolongation. Furthermore, all the DCM-CHF model dogs showed manifestations of congestive heart failure and enlargement of left ventricles. Based on the lengthening of mid-layer MAPD from 257.35 ms to 276.30 ms (P<0.0001) and increase of TDR from 27.58 ms to 33.80 ms (P equals;0.002) in DCM-CHF model due to the structural disorders of myocardium compared with the normal dog, LV-Epi and BiV pacing also led to the effect of prolonging MAPD of three layers of the myocardium and enlarging TDR. From these results we make the conclusions that prolongation of MAPD of subendocardial, subepicardial and mid-layer myocardium and increase in TDR during pacing participating of LV (LV-Epi, BiV) may contribute to the formation of unidirectional block and reentry, which play roles or at least are the high risk factors in the development of malignant ventricular arrhythmia, especially in case of structural disorders of myocardium. These findings must be considered seriously when ventricular resynchronization therapy is performed to congestive heart failure patients.

Mortality and comorbidities in patients with multiple sclerosis compared with a population without multiple sclerosis: An observational study using the US Department of Defense administrative claims database.

PubMed

Capkun, Gorana; Dahlke, Frank; Lahoz, Raquel; Nordstrom, Beth; Tilson, Hugh H; Cutter, Gary; Bischof, Dorina; Moore, Alan; Simeone, Jason; Fraeman, Kathy; Bancken, Fabrice; Geissbühler, Yvonne; Wagner, Michael; Cohan, Stanley

2015-11-01

Data are limited for mortality and comorbidities in patients with multiple sclerosis (MS). Compare mortality rates and event rates for comorbidities in MS (n=15,684) and non-MS (n=78,420) cohorts from the US Department of Defense (DoD) database. Comorbidities and all-cause mortality were assessed using the database. Causes of death (CoDs) were assessed through linkage with the National Death Index. Cohorts were compared using mortality (MRR) and event (ERR) rate ratios. All-cause mortality was 2.9-fold higher in the MS versus non-MS cohort (MRR, 95% confidence interval [CI]: 2.9, 2.7-3.2). Frequent CoDs in the MS versus non-MS cohort were infectious diseases (6.2, 4.2-9.4), diseases of the nervous (5.8, 3.7-9.0), respiratory (5.0, 3.9-6.4) and circulatory (2.1, 1.7-2.7) systems and suicide (2.6, 1.3-5.2). Comorbidities including sepsis (ERR, 95% CI: 5.7, 5.1-6.3), ischemic stroke (3.8, 3.5-4.2), attempted suicide (2.4, 1.3-4.5) and ulcerative colitis (2.0, 1.7-2.3), were higher in the MS versus non-MS cohort. The rate of cancers was also higher in the MS versus the non-MS cohort, including lymphoproliferative disorders (2.2, 1.9-2.6) and melanoma (1.7, 1.4-2.0). Rates of mortality and several comorbidities are higher in the MS versus non-MS cohort. Early recognition and management of comorbidities may reduce premature mortality and improve quality of life in patients with MS. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Analysis Concerning the Inspection Threshold for Multi-Site Damage.

DOT National Transportation Integrated Search

1993-12-01

Periodic inspections, at a prescribed interval, for Multi-Site Damage (MS) in longitudinal fuselage lap-joints start when the aircraft has accumulated a certain number of flights, the inspection threshold. The work reported here was an attempt to obt...

Cardiac Repolarization Abnormalities and Potential Evidence for Loss of Cardiac Sodium Currents on ECGs of Patients with Chagas' Heart Disease

NASA Technical Reports Server (NTRS)

Schlegel, T. T.; Medina, R.; Jugo, D.; Nunez, T. J.; Borrego, A.; Arellano, E.; Arenare, B.; DePalma, J. L.; Greco, E. C.; Starc, V.

2007-01-01

Some individuals with Chagas disease develop right precordial lead ST segment elevation in response to an ajmaline challenge test, and the prevalence of right bundle branch block (RBBB) is also high in Chagas disease. Because these same electrocardiographic abnormalities occur in the Brugada syndrome, which involves genetically defective cardiac sodium channels, acquired damage to cardiac sodium channels may also occur in Chagas disease. We studied several conventional and advanced resting 12-lead/derived Frank-lead ECG parameters in 34 patients with Chagas -related heart disease (mean age 39 14 years) and in 34 age-/gender-matched healthy controls. All ECG recordings were of 5-10 min duration, obtained in the supine position using high fidelity hardware/software (CardioSoft, Houston, TX). Even after excluding those Chagas patients who had resting BBBs, tachycardia and/or pathologic arrhythmia (n=8), significant differences remained in multiple conventional and advanced ECG parameters between the Chagas and control groups (n=26/group), especially in their respective QT interval variability indices, maximal spatial QRS-T angles and low frequency HRV powers (p=0.0006, p=0.0015 and p=0.0314 respectively). In relation to the issue of potential damage to cardiac sodium channels, the Chagas patients had: 1) greater than or equal to twice the incidence of resting ST segment elevation in leads V1-V3 (n=10/26 vs. n=5/26) and of both leftward (n=5/26 versus n=0/26) and rightward (n=7/26 versus n=3/26) QRS axis deviation than controls; 2) significantly increased filtered (40-250 Hz) QRS interval durations (92.1 8.5 versus 85.3 plus or minus 9.0 ms, p=0.022) versus controls; and 3) significantly decreased QT and especially JT interval durations versus controls (QT interval: 387.5 plus or minus 26.4 versus 408.9 plus or minus 34.6 ms, p=0.013; JT interval: 290.5 plus or minus 26.3 versus 314.8 plus or minus 31.3 ms; p=0.0029). Heart rates and Bazett-corrected QTc/JTc intervals were not significantly different between groups. Patients with Chagas heart disease have increased cardiac repolarization abnormalities, especially by advanced ECG. Moreover, as a group, they have decreased uncorrected JT and QT interval durations and increased filtered QRS interval durations (versus age/gender-matched controls), all suggesting a potential loss of cardiac sodium channel function that might be mediated, in part, by cardiac autonomic damage. Overall findings support Brugada et al's recent hypothesis that the pathway leading to sudden death may often be similar in Chagas' disease and Brugada syndrome i.e., damage to the sodium channel (infectious/immunologic/autonomic in Chagas' genetic in Brugada) with consequent loss of sodium currents may facilitate a phase II-reentry based arrhythmic substrate for ventricular fibrillation in both conditions. In general, JT interval-related results have been underreported in the Chagas literature.

Kinetics and components of the flash photocurrent of isolated retinal rods of the larval salamander, Ambystoma tigrinum.

PubMed Central

Cobbs, W H; Pugh, E N

1987-01-01

1. Membrane currents initiated by intense, 20 microseconds flashes (photocurrents) were recorded from isolated salamander rods by combined extracellular suction electrodes and intracellular tight-seal electrodes either in current or voltage clamp mode. The magnitudes (mean +/- 2 S.E.M.) of the maximal photoresponses recorded by the suction and by the intracellular electrode respectively were 40 +/- 5 pA (n = 18) and 35 +/- 7 mV (n = 8) for current clamp at zero current; 43 +/- 9 pA and 66 +/- 13 (n = 11) pA for voltage clamp at the zero-current holding potential, -24 +/- 3 mV. 2. Photocurrents initiated by flashes isomerizing 0.1% or more of the outer segment's rhodopsin achieved a saturated velocity and were 95% complete in less than 50 ms. The effect of incrementing flash intensity above 0.1% isomerization can be described as a translation of the photocurrent along the time axis towards the origin. Within the interval 0-50 ms the latter two-thirds of the velocity-saturated photocurrent is well described as a single-exponential decay. The decay was much faster in voltage clamp (2.8 +/- 1.2 ms, n = 11) than in current clamp mode (17 +/- 5 ms, n = 17). 3. The initial third of the velocity-saturated photocurrent, occurring over the interval from the flash to the onset of exponential decay, followed about the same time course in current and voltage clamp. The time interval occupied by this initial 'latent' phase decreased with increasing flash intensity and attained an apparent minimum of about 7 ms in response to flashes isomerizing 10% or more of the rhodopsin at ca. 22 degrees C. 4. The hypothesis that the decay of outer segment light-sensitive membrane current is the same in current and voltage clamp was supported by an analysis of the difference between outer segment currents measured successively in the two recording modes. First, the tail of the difference current decayed exponentially with a time constant approximately equal to R x C, where R and C are independently estimated slope resistance and capacitance of the rod. Secondly, the integral of the difference current, when divided by outer segment capacitance, closely approximated the hyperpolarizing light response measured under current clamp. Thus, displacement current accounted for the difference between photocurrents measured in current and voltage clamp.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2832596

Dissociating Long and Short-term Memory in Three-Month-Old Infants Using the Mismatch Response to Voice Stimuli

PubMed Central

Zinke, Katharina; Thöne, Leonie; Bolinger, Elaina M.; Born, Jan

2018-01-01

Auditory event-related potentials (ERPs) have been successfully used in adults as well as in newborns to discriminate recall of longer-term and shorter-term memories. Specifically the Mismatch Response (MMR) to deviant stimuli of an oddball paradigm is larger if the deviant stimuli are highly familiar (i.e., retrieved from long-term memory) than if they are unfamiliar, representing an immediate change to the standard stimuli kept in short-term memory. Here, we aimed to extend previous findings indicating a differential MMR to familiar and unfamiliar deviants in newborns (Beauchemin et al., 2011), to 3-month-old infants who are starting to interact more with their social surroundings supposedly based on forming more (social) long-term representations. Using a voice discrimination paradigm, each infant was repeatedly presented with the word “baby” (400 ms, interstimulus interval: 600 ms, 10 min overall duration) pronounced by three different female speakers. One voice that was unfamiliar to the infants served as the frequently presented “standard” stimulus, whereas another unfamiliar voice served as the “unfamiliar deviant” stimulus, and the voice of the infant’s mother served as the “familiar deviant.” Data collection was successful for 31 infants (mean age = 100 days). The MMR was determined by the difference between the ERP to standard stimuli and the ERP to the unfamiliar and familiar deviant, respectively. The MMR to the familiar deviant (mother’s voice) was larger, i.e., more positive, than that to the unfamiliar deviant between 100 and 400 ms post-stimulus over the frontal and central cortex. However, a genuine MMR differentiating, as a positive deflection, between ERPs to familiar deviants and standard stimuli was only found in the 300–400 ms interval. On the other hand, a genuine MMR differentiating, as a negative deflection, between ERPs to unfamiliar deviants from ERPs to standard stimuli was revealed for the 200–300 ms post-stimulus interval. Overall results confirm a differential MMR response to unfamiliar and familiar deviants in 3-month-olds, with the earlier negative MMR to unfamiliar deviants likely reflecting change detection based on comparison processes in short-term memory, and the later positive MMR to familiar deviants reflecting subsequent long-term memory-based processing of stimulus relevance. PMID:29441032

Dissociating Long and Short-term Memory in Three-Month-Old Infants Using the Mismatch Response to Voice Stimuli.

PubMed

Zinke, Katharina; Thöne, Leonie; Bolinger, Elaina M; Born, Jan

2018-01-01

Auditory event-related potentials (ERPs) have been successfully used in adults as well as in newborns to discriminate recall of longer-term and shorter-term memories. Specifically the Mismatch Response (MMR) to deviant stimuli of an oddball paradigm is larger if the deviant stimuli are highly familiar (i.e., retrieved from long-term memory) than if they are unfamiliar, representing an immediate change to the standard stimuli kept in short-term memory. Here, we aimed to extend previous findings indicating a differential MMR to familiar and unfamiliar deviants in newborns (Beauchemin et al., 2011), to 3-month-old infants who are starting to interact more with their social surroundings supposedly based on forming more (social) long-term representations. Using a voice discrimination paradigm, each infant was repeatedly presented with the word "baby" (400 ms, interstimulus interval: 600 ms, 10 min overall duration) pronounced by three different female speakers. One voice that was unfamiliar to the infants served as the frequently presented "standard" stimulus, whereas another unfamiliar voice served as the "unfamiliar deviant" stimulus, and the voice of the infant's mother served as the "familiar deviant." Data collection was successful for 31 infants (mean age = 100 days). The MMR was determined by the difference between the ERP to standard stimuli and the ERP to the unfamiliar and familiar deviant, respectively. The MMR to the familiar deviant (mother's voice) was larger, i.e., more positive, than that to the unfamiliar deviant between 100 and 400 ms post-stimulus over the frontal and central cortex. However, a genuine MMR differentiating, as a positive deflection, between ERPs to familiar deviants and standard stimuli was only found in the 300-400 ms interval. On the other hand, a genuine MMR differentiating, as a negative deflection, between ERPs to unfamiliar deviants from ERPs to standard stimuli was revealed for the 200-300 ms post-stimulus interval. Overall results confirm a differential MMR response to unfamiliar and familiar deviants in 3-month-olds, with the earlier negative MMR to unfamiliar deviants likely reflecting change detection based on comparison processes in short-term memory, and the later positive MMR to familiar deviants reflecting subsequent long-term memory-based processing of stimulus relevance.

Laurentide Ice Sheet Meltwater Geochemistry During the MIS 3 Warm Phase from Single-Shell Trace Element and Isotope Measurements

NASA Astrophysics Data System (ADS)

Branson, O.; Vetter, L.; Fehrenbacher, J. S.; Spero, H. J.

2016-12-01

The geochemical variability between individual foraminifera within single core intervals records both palaeo-oecanographic conditions and ecology. Within the biological context of foraminiferal species, this population variability may be interpreted to provide unparalleled paleoenvironmental information. For example, coupled trace element and stable isotope analyses of single O. universa offer a powerful tool for reconstructing the δ18O of Laurentide Ice Sheet (LIS) meltwater, by calculating the intercept between temperature-corrected δ18O water and Ba/Ca salinity estimates (Vetter et al., in review). This offers valuable insights into the dynamics of ice sheet melting at the end of the last glacial maximum. Here we apply similar coupled single-shell laser ablation (LA-ICP-MS) and isotope ratio mass spectrometry (IRMS) techniques to explore the δ18O of Laurentide meltwater during H4 and bracketing intervals. The application of these methods to down-core samples requires the development of robust LA-ICP-MS data processing techniques to identify primary signals within Ba contaminated samples, and careful consideration of palaeo Ba/Ca-salinity relationships. Our analyses offer a significant advance in systematic LA-ICP-MS data processing methods, offer constraints on the variability of riverine Ba fluxes, and ultimately provide δ18O estimates of LIS meltwater during H4.

The modulation rate transfer function of a harbour porpoise (Phocoena phocoena).

PubMed

Linnenschmidt, Meike; Wahlberg, Magnus; Damsgaard Hansen, Janni

2013-02-01

During echolocation, toothed whales produce ultrasonic clicks at extremely rapid rates and listen for the returning echoes. The auditory brainstem response (ABR) duration was evaluated in terms of latency between single peaks: 5.5 ms (from peak I to VII), 3.4 ms (I-VI), and 1.4 ms (II-IV). In comparison to the killer whale and the bottlenose dolphin, the ABR of the harbour porpoise has shorter intervals between the peaks and consequently a shorter ABR duration. This indicates that the ABR duration and peak latencies are possibly related to the relative size of the auditory structures of the central nervous system and thus to the animal's size. The ABR to a sinusoidal amplitude modulated stimulus at 125 kHz (sensitivity threshold 63 dB re 1 μPa rms) was evaluated to determine the modulation rate transfer function of a harbour porpoise. The ABR showed distinct envelope following responses up to a modulation rate of 1,900 Hz. The corresponding calculated equivalent rectangular duration of 263 μs indicates a good temporal resolution in the harbour porpoise auditory system similar to the one for the bottlenose dolphin. The results explain how the harbour porpoise can follow clicks and echoes during echolocation with very short inter click intervals.

Switching between univalent task-sets in schizophrenia: ERP evidence of an anticipatory task-set reconfiguration deficit.

PubMed

Karayanidis, Frini; Nicholson, Rebecca; Schall, Ulrich; Meem, Lydia; Fulham, Ross; Michie, Patricia T

2006-10-01

The present study used behavioral and event-related potential (ERP) indices of task-switching to examine whether schizophrenia patients have a specific deficit in anticipatory task-set reconfiguration. Participants switched between univalent tasks in an alternating runs paradigms with blocked response-stimulus interval (RSI) manipulation (150, 300, 600, and 1200ms). Nineteen high functioning people with schizophrenia were compared to controls that were matched for age, gender, education and premorbid IQ estimate. Schizophrenia patients had overall increased RT, but no increase in corrected RT switch cost. In the schizophrenia group, ERPs showed reduced activation of the differential positivity in anticipation of switch trial at the optimal 600ms RSI and reduced activation of the frontal post-stimulus switch negativity at both 600 and 1200ms RSI compared to the control group. Despite no behavioral differences in task switching performance, anticipatory and stimulus-triggered ERP indices of task-switching suggest group differences in processing of switch and repeat trials, especially at longer RSI conditions that for control participants provide opportunity for anticipatory activation of task-set reconfiguration processes. These results are compatible with impaired implementation of endogenously driven processes in schizophrenia and greater reliance on external task cues, especially at long preparation intervals.

Perception and the strongest sensory memory trace of multi-stable displays both form shortly after the stimulus onset.

PubMed

Pastukhov, Alexander

2016-02-01

We investigated the relation between perception and sensory memory of multi-stable structure-from-motion displays. The latter is an implicit visual memory that reflects a recent history of perceptual dominance and influences only the initial perception of multi-stable displays. First, we established the earliest time point when the direction of an illusory rotation can be reversed after the display onset (29-114 ms). Because our display manipulation did not bias perception towards a specific direction of illusory rotation but only signaled the change in motion, this means that the perceptual dominance was established no later than 29-114 ms after the stimulus onset. Second, we used orientation-selectivity of sensory memory to establish which display orientation produced the strongest memory trace and when this orientation was presented during the preceding prime interval (80-140 ms). Surprisingly, both estimates point towards the time interval immediately after the display onset, indicating that both perception and sensory memory form at approximately the same time. This suggests a tighter integration between perception and sensory memory than previously thought, warrants a reconsideration of its role in visual perception, and indicates that sensory memory could be a unique behavioral correlate of the earlier perceptual inference that can be studied post hoc.

Sensori-motor synchronisation variability decreases as the number of metrical levels in the stimulus signal increases.

PubMed

Madison, Guy

2014-03-01

Timing performance becomes less precise for longer intervals, which makes it difficult to achieve simultaneity in synchronisation with a rhythm. The metrical structure of music, characterised by hierarchical levels of binary or ternary subdivisions of time, may function to increase precision by providing additional timing information when the subdivisions are explicit. This hypothesis was tested by comparing synchronisation performance across different numbers of metrical levels conveyed by loudness of sounds, such that the slowest level was loudest and the fastest was softest. Fifteen participants moved their hand with one of 9 inter-beat intervals (IBIs) ranging from 524 to 3,125 ms in 4 metrical level (ML) conditions ranging from 1 (one movement for each sound) to 4 (one movement for every 8th sound). The lowest relative variability (SD/IBI<1.5%) was obtained for the 3 longest IBIs (1600-3,125 ms) and MLs 3-4, significantly less than the smallest value (4-5% at 524-1024 ms) for any ML 1 condition in which all sounds are identical. Asynchronies were also more negative with higher ML. In conclusion, metrical subdivision provides information that facilitates temporal performance, which suggests an underlying neural multi-level mechanism capable of integrating information across levels. © 2013.

Myeloid Sarcoma Predicts Superior Outcome in Pediatric AML; Can Cytogenetics Solve the Puzzle?

PubMed

Pramanik, Raja; Tyagi, Anudishi; Chopra, Anita; Kumar, Akash; Vishnubhatla, Sreenivas; Bakhshi, Sameer

2018-06-01

The purpose of our study was to evaluate the clinical, cytogenetic, and molecular features, and survival outcomes in patients with acute myeloid leukemia (AML) with myeloid sarcoma (MS) and compare them with patients with AML without MS. This was a retrospective analysis of de novo pediatric AML patients with or without MS diagnosed at our cancer center between June 2003 and June 2016. MS was present in 121 of 570 (21.2%), the most frequent site being the orbit. Patients with MS had a younger median age (6 years vs. 10 years) and presented with higher hemoglobin and platelet but lower white blood cell count compared with patients without MS. Further, t (8; 21) (P < .01), loss of Y chromosome (P < .01), and deletion 9q (P = .03) were significantly higher in patients with AML with MS. Event-free survival (EFS; P = .003) and overall survival (OS; P = .001) were better among patients with AML with MS (median EFS 21.0 months and median OS 37.1 months) compared with those with AML without MS (median EFS 11.2 months and median OS 16.2 months). The t (8; 21) was significantly associated with MS (odds ratio, 3.92). In a comparison of the 4 groups divided according to the presence or absence of MS and t (8; 21), the subgroup of patients having MS without concomitant t (8; 21) was the only group to have a significantly better OS (hazard ratio, 0.53; 95% confidence interval, 0.34-0.82; P = .005). Although t (8; 21) was more frequently associated with MS, it did not appear to be the reason for better outcome. Copyright © 2018 Elsevier Inc. All rights reserved.

Antipsychotic adjunctive therapy to mood stabilizers and 1-year rehospitalization rates in bipolar disorder: A cohort study.

PubMed

Hochman, Eldar; Krivoy, Amir; Schaffer, Ayal; Weizman, Abraham; Valevski, Avi

2016-12-01

Antipsychotic adjunctive therapy to mood stabilizers (MSs) may improve relapse prevention; however, only a few naturalistic studies, reflecting more generalizable bipolar disorder (BD) samples, support this notion. We compared the 1-year rehospitalization rates of manic patients with bipolar I disorder (BD-I) who were discharged with MS (lithium or valproate) monotherapy or with adjunctive atypical or typical antipsychotic therapy. A total of 201 patients with BD-I who were hospitalized with manic episodes between 2005 and 2013 were retrospectively followed for 1-year rehospitalization rates according to treatment at discharge: MS monotherapy, MS with atypical antipsychotics, and MS with typical antipsychotics. Additionally, time to rehospitalization during the 1-year period after discharge was compared between treatment groups. Multivariable survival analyses adjusted for covariates known to influence rehospitalization were conducted. Rehospitalization rates within 1 year were significantly lower in the MS with atypical antipsychotics group (6.3%) compared to the MS monotherapy group (24.3%, P=.008) and to the MS with typical antipsychotics group (20.6%, P=.02). Time to rehospitalization was significantly longer for the MS with atypical antipsychotics group (345.5 days) compared to the MS monotherapy group (315.1 days, P=.006) and to the MS with typical antipsychotics group (334.1 days, P=.02). The MS with atypical antipsychotics group had a significantly reduced adjusted risk of rehospitalization (hazard ratio=0.17, 95% confidence interval: 0.05-0.61, P=.007) compared to the MS monotherapy group. Atypical antipsychotic adjunctive therapy to MSs may be more effective than MS monotherapy in preventing rehospitalization during the 1-year period after a BD manic episode. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cognitive Motor Interference in Multiple Sclerosis: Insights From a Systematic Quantitative Review.

PubMed

Learmonth, Yvonne C; Ensari, Ipek; Motl, Robert W

2017-06-01

To synthesize the evidence for differences in cognitive motor interference (CMI) between persons with multiple sclerosis (MS) and those without MS by using systematic review and meta-analysis. EMBASE, PubMed, ScienceDirect, Scopus, SPORTDiscus, and Web of Science. Our focused literature search was informed by past systematic reviews of CMI during walking in MS. The key terms searched included Multiple sclerosis and synonyms of motor function (eg, Gait disorders, Gait, Walking, Balance, or Fall) and motor and cognitive functions (eg, Cognitive motor interference or Thinking). From the 116 abstract-identified articles, 13 experimental studies were selected for the final analysis and were rated using the Quality Assessment of Diagnostic Accuracy Studies tool. A meta-analysis was performed for all considered outcomes. The results yielded a small overall effect size (ES) of .08 (SE=.17; 95% confidence interval, -.25 to .40; z=.49; P>.05), which indicated a nonsignificant minimal difference in CMI between persons with MS and those without MS. The moderator analysis for motor task (mobility task: ES, .22; postural task: ES, -.11) was not significantly different between persons with MS and those without MS. The moderator analysis for cognitive task (verbal fluency task: ES, .66; mental tracking task: ES, .04; discrimination and decision-making task: ES, -.30) resulted in a significant difference in CMI between persons with MS and those without MS (P<.05). We provide evidence that overall there is a minimal difference in CMI between persons with MS and those without MS. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Association between hormones and metabolic syndrome in older Italian men.

PubMed

Maggio, Marcello; Lauretani, Fulvio; Ceda, Gian Paolo; Bandinelli, Stefania; Basaria, Shehzad; Ble, Alessandro; Egan, Josephine; Paolisso, Giuseppe; Najjar, Samer; Jeffrey Metter, E; Valenti, Giorgio; Guralnik, Jack M; Ferrucci, Luigi

2006-12-01

To determine whether low levels of testosterone, sex hormone binding globulin (SHBG), insulin-like growth factor-1 (IGF-1), and dehydroepiandrosterone sulfate (DHEAS) and high levels of cortisol and leptin would be associated with metabolic syndrome (MS). Cross-sectional. Population-based sample of older Italian men. Four hundred fifty-two men aged 65 and older enrolled in the Invecchiare in Chianti (InCHIANTI) study. Complete data on testosterone, cortisol, DHEAS, SHBG, fasting insulin, IGF-1 and leptin. MS was defined according to Adult Treatment Panel III criteria. MS was present in 73 men (15.8% of the sample). After adjusting for confounders, total testosterone (P < .05) and log (SHBG) (P < .001) were inversely associated, whereas log (leptin) was positively associated with MS (P < .001). Independent of age, log (SHBG) was positively associated with high-density lipoprotein cholesterol (P < .05) and negatively associated with abdominal obesity (P < .001) and triglycerides (P < .001). Log (leptin) was significantly associated with each component of MS. Cortisol, DHEAS, free and bioavailable testosterone, and IGF-1 were not associated with MS. Having three or more hormones in the lower (for hormones lower in MS) or the upper (for hormones higher in MS) quartile was associated with three times the risk of being affected by MS (odds ratio = 2.8, 95% confidence interval = 1.3-6.9) (P = .005), compared with not having this condition. Total testosterone and SHBG are negatively and leptin is positively associated with MS in older men. Whether specific patterns of hormonal dysregulation predict the development of MS should be tested in longitudinal studies.

Prevalence and mortality of patients with multiple sclerosis in France in 2012: a study based on French health insurance data.

PubMed

Foulon, Stéphanie; Maura, Géric; Dalichampt, Marie; Alla, François; Debouverie, Marc; Moreau, Thibault; Weill, Alain

2017-06-01

Data on the prevalence of multiple sclerosis (MS) in France are scarce. National and regional updated estimates are needed to better plan health policies. In this nationwide study, we provided estimates of the prevalence of MS in France in 2012 and mortality rate in 2013. MS cases were identified in the French national health insurance database (SNIIRAM-PMSI) using reimbursement data for disease-modifying treatment, long-term disease status for MS, disability pension for MS, and hospitalisation for MS (MS ICD-10 code: G35). We identified 99,123 MS cases, corresponding to an overall crude prevalence rate of 151.2 per 100,000 inhabitants [95% confidence interval (CI) 150.3-152.2]: 210.0 per 100,000 in women (95% CI 208.4-211.5) and 88.7 per 100,000 in men (95% CI 87.6-89.7). The overall prevalence rate was 155.6 per 100,000 inhabitants (95% CI 154.7-156.6) after standardization on the 2013-European population. We observed a prevalence gradient with a higher prevalence (190-200 per 100,000) in North-Eastern France and a lower prevalence in Southern and Western France (126-140). The crude mortality rate in 2013 was 13.7 per 1,000 MS cases (11.4 in women and 20.3 in men). The standardized mortality ratio was 2.56 (95% CI 2.41-2.72). Our results revise upwards the estimation of MS prevalence in France and confirm the excess mortality of MS patients compared to the general population.

Could Heterozygous Beta Thalassemia Provide Protection Against Multiple Sclerosis?

PubMed Central

Cikrikcioglu, Mehmet Ali; Ozcan, Muhammed Emin; Halac, Gulistan; Gultepe, Ilhami; Celik, Kenan; Sekin, Yahya; Eser, Elif Ece; Burhan, Sebnem; Cetin, Guven; Uysal, Omer

2016-01-01

Background Heterozygous beta thalassemia (HBT) has been proposed to increase the risk of developing autoimmune disease. Our aim in this study was to examine the prevalence of HBT among multiple sclerosis (MS) patients. Material/Methods HBT frequency was investigated in our MS group (243 patients with MS). Hemoglobin electrophoresis (HE) was carried out if MS patients had a mean corpuscular volume of (MCV) <80 fL and a mean corpuscular hemoglobin level of (MCH) <27 pg/L according to a complete blood count (CBC). If MCV was lower than 80 fL, MCH was lower than 27 pg/L, and Hemoglobin A2 equal to or higher than 3.5%, a diagnosis of HBT was established. The frequency of patients with HBT in our MS patient group was statistically compared with the prevalence of HBT in the city of Istanbul, where our MS patients lived. Results The HBT prevalence was 0.823% (2 patients) in the MS patient group. The prevalence of HBT in Istanbul has been reported to be 4.5%. According to the z-test, the HBT prevalence in our MS patient group was significantly lower than that in Istanbul (Z=6.3611, two-sided p value <0.0001, 95% confidence interval of prevalence of HBT in our MS patient group: 0.000998–0.029413). Conclusions Contrary to our hypothesis at the outset of study, the reduced HBT prevalence in the MS group compared to HBT frequency in the city of Istanbul might indicate that HBT is protective against MS. PMID:27941710

Cardiac conductive disturbance in patients with polycystic ovary syndrome.

PubMed

Huang, Jen-Hung; Tsai, Jen-Chen; Hsu, Ming-I; Chen, Yi-Jen

2010-12-01

Polycystic ovary syndrome (PCOS) is the most common endocrine abnormality of reproductive-aged women and increases the risk of cardiovascular disease. However, the effects of PCOS on electrocardiograms (ECGs) are not fully elucidated. The aim of this study was to evaluate the characteristics of ECGs in patients with PCOS. This study included 24 patients with PCOS and 12 patients without PCOS. The heart rate, PR interval, QRS duration, Sokolow-Lyon voltage (SV1 + RV5/6), Cornell voltage (RaVL + SV3), QT interval and QTc interval were measured in 12-lead ECGs. The QRS duration was wider in patients with PCOS than those without PCOS (91 ± 8 vs. 81 ± 10 ms, p < 0.05). The heart rate, PR interval, Sokolow-Lyon voltage, product of the QRS duration times Cornell voltage combination, QT interval, QTc interval, QT dispersion and QTc dispersion were similar between the two groups. PCOS is associated with a widening QRS duration, which may contribute to its increased cardiovascular risks.

The Effect of Neural Noise on Spike Time Precision in a Detailed CA3 Neuron Model

PubMed Central

Kuriscak, Eduard; Marsalek, Petr; Stroffek, Julius; Wünsch, Zdenek

2012-01-01

Experimental and computational studies emphasize the role of the millisecond precision of neuronal spike times as an important coding mechanism for transmitting and representing information in the central nervous system. We investigate the spike time precision of a multicompartmental pyramidal neuron model of the CA3 region of the hippocampus under the influence of various sources of neuronal noise. We describe differences in the contribution to noise originating from voltage-gated ion channels, synaptic vesicle release, and vesicle quantal size. We analyze the effect of interspike intervals and the voltage course preceding the firing of spikes on the spike-timing jitter. The main finding of this study is the ranking of different noise sources according to their contribution to spike time precision. The most influential is synaptic vesicle release noise, causing the spike jitter to vary from 1 ms to 7 ms of a mean value 2.5 ms. Of second importance was the noise incurred by vesicle quantal size variation causing the spike time jitter to vary from 0.03 ms to 0.6 ms. Least influential was the voltage-gated channel noise generating spike jitter from 0.02 ms to 0.15 ms. PMID:22778784

Identifying the translational gap in the evaluation of drug-induced QTc interval prolongation

PubMed Central

Chain, Anne SY; Dubois, Vincent FS; Danhof, Meindert; Sturkenboom, Miriam CJM; Della Pasqua, Oscar

2013-01-01

Aims Given the similarities in QTc response between dogs and humans, dogs are used in pre-clinical cardiovascular safety studies. The objective of our investigation was to characterize the PKPD relationships and identify translational gaps across species following the administration of three compounds known to cause QTc interval prolongation, namely cisapride, d, l-sotalol and moxifloxacin. Methods Pharmacokinetic and pharmacodynamic data from experiments in conscious dogs and clinical trials were included in this analysis. First, pharmacokinetic modelling and deconvolution methods were applied to derive drug concentrations at the time of each QT measurement. A Bayesian PKPD model was then used to describe QT prolongation, allowing discrimination of drug-specific effects from other physiological factors known to alter QT interval duration. A threshold of ≥10 ms was used to explore the probability of prolongation after drug administration. Results A linear relationship was found to best describe the pro-arrhythmic effects of cisapride, d,l-sotalol and moxifloxacin both in dogs and in humans. The drug-specific parameter (slope) in dogs was statistically significantly different from humans. Despite such differences, our results show that the probability of QTc prolongation ≥10 ms in dogs nears 100% for all three compounds at the therapeutic exposure range in humans. Conclusions Our findings indicate that the slope of PKPD relationship in conscious dogs may be used as the basis for the prediction of drug-induced QTc prolongation in humans. Furthermore, the risk of QTc prolongation can be expressed in terms of the probability associated with an increase ≥10 ms, allowing direct inferences about the clinical relevance of the pro-arrhythmic potential of a molecule. PMID:23351036

Changes in Choice Reaction Time During and After 8 Days Exhaustive Cycling Are Not Related to Changes in Physical Performance.

PubMed

Ten Haaf, Twan; van Staveren, Selma; Iannetta, Danilo; Roelands, Bart; Meeusen, Romain; Piacentini, Maria F; Foster, Carl; Koenderman, Leo; Daanen, Hein A M; de Koning, Jos J

2018-04-01

Reaction time has been proposed as a training monitoring tool, but to date, results are equivocal. Therefore, it was investigated whether reaction time can be used as a monitoring tool to establish overreaching. The study included 30 subjects (11 females and 19 males, age: 40.8 [10.8] years, VO 2max : 51.8 [6.3] mL/kg/min) who participated in an 8-day cycling event. The external exercise load increased approximately 900% compared with the preparation period. Performance was measured before and after the event using a maximal incremental cycling test. Subjects with decreased performance after the event were classified as functionally overreached (FOR) and others as acutely fatigued (AF). A choice reaction time test was performed 2 weeks before (pre), 1 week after (post), and 5 weeks after (follow-up), as well as at the start and end of the event. A total of 14 subjects were classified as AF and 14 as FOR (2 subjects were excluded). During the event, reaction time at the end was 68 ms (95% confidence interval, 46-89) faster than at the start. Reaction time post event was 41 ms (95% confidence interval, 12-71) faster than pre event and follow-up was 55 ms faster (95% confidence interval, 26-83). The time by class interaction was not significant during (P = .26) and after (P = .43) the event. Correlations between physical performance and reaction time were not significant (all Ps > .30). No differences in choice reaction time between AF and FOR subjects were observed. It is suggested that choice reaction time is not valid for early detection of overreaching in the field.

Children with Heavy Prenatal Alcohol Exposure have Different Frequency Domain Signal Characteristics when Producing Isometric Force

PubMed Central

Nguyen, Tanya T.; Ashrafi, Ashkan; Thomas, Jennifer D.; Riley, Edward P.; Simmons, Roger W.

2013-01-01

To extend our current understanding of the teratogenic effects of prenatal alcohol exposure on the control of isometric force, the present study investigated the signal characteristics of power spectral density functions resulting from sustained control of isometric force by children with and without heavy prenatal exposure to alcohol. It was predicted that the functions associated with the force signals would be fundamentally different for the two groups. Twenty-five children aged between 7 and 17 years with heavy prenatal alcohol exposure and 21 non-alcohol exposed control children attempted to duplicate a visually represented target force by pressing on a load cell. The level of target force (5 and 20% of maximum voluntary contraction) and the time interval between visual feedback (20ms, 320ms and 740ms) were manipulated. A multivariate spectral estimation method with sinusoidal windows was applied to individual isometric force-time signals. Analysis of the resulting power spectral density functions revealed that the alcohol-exposed children had a lower mean frequency, less spectral variability, greater peak power and a lower frequency at which peak power occurred. Furthermore, mean frequency and spectral variability produced by the alcohol-exposed group remained constant across target load and visual feedback interval, suggesting that these children were limited to making long-time scale corrections to the force signal. In contrast, the control group produced decreased mean frequency and spectral variability as target force and the interval between visual feedback increased, indicating that when feedback was frequently presented these children used the information to make short-time scale adjustments to the ongoing force signal. Knowledge of these differences could facilitate the design of motor rehabilitation exercises that specifically target isometric force control deficits in alcohol-exposed children. PMID:23238099

Neural and Muscular Contributions to the Age-Related Reductions in Rapid Strength.

PubMed

Gerstner, Gena R; Thompson, Brennan J; Rosenberg, Joseph G; Sobolewski, Eric J; Scharville, Michael J; Ryan, Eric D

2017-07-01

The purposes of this study were to investigate the age-related differences in absolute and normalized plantarflexion rate of torque development (RTD) at early (0-50 ms) and late (100-200 ms) time intervals and to examine specific neural and muscular mechanisms contributing to these differences. Thirty-two young (20.0 ± 2.1 yr) and 20 older (69.5 ± 3.3 yr) recreationally active men performed rapid plantarflexion isometric muscle actions to examine absolute and normalized RTD and muscle activation using EMG at early and late time intervals. Ultrasonography was used to examine medial gastrocnemius muscle size, echo intensity (EI), and muscle architecture (fascicle length [FL] and pennation angle [PA]). The older men were weaker (23.9%, P < 0.001) and had lower later absolute and normalized RTD (P = 0.001-0.034) variables when compared with the young men. The older men also had higher EI (P < 0.001), smaller PA (P = 0.004), and lower later EMG amplitude values (P = 0.009-0.046). However, there were no differences in early RTD and EMG amplitude values, muscle size, or FL between groups (P = 0.097-0.914). Lower late RTD values were related to higher EI, smaller PA, and lower EMG amplitude values (r = -0.28-0.59, P = 0.001-0.044); however, late RTD values were no longer related to PA after normalizing to peak torque. Age-related alterations in muscle quality (EI), architecture, and muscle activation may influence rapid torque production at late time intervals (≥100 ms) from contraction onset. These findings highlight specific neuromuscular factors that influence the age-related reductions in RTD, which has been shown to significantly influence function and performance in older adults.

Stratigraphic variations in the biomarker distribution of the Moreno Formation: Their correlation with San Joaquin basin oils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bac, M.G.; Schulein, B.J.

1990-05-01

Variability in the biomarker compositions of petroleums is typically employed in the recognition and distinction of contributions from different source rocks. We demonstrate that the fluctuations in the biomarker distributions of different intervals within a single source rock sequence appear to account for specific compositional differences in a suite of oils from the San Joaquin basin California. Rock-Eval pyrolysis studies of a 100-m-thick immature, laminated, marine shale sequence within the Upper Cretaceous lo lower Paleocene portion of the Moreno Formation reveals TOC (total organic carbon) contents consistently around 2% and moderate hydrogen indices (i.e., 175-300 mg HC/g org. C) characteristicsmore » suggestive of a uniform depositional sequence with source rock potential. Analyses of the extractable aliphatic hydrocarbons of cored samples taken at approximately 10-m intervals from the sequence reveal significant variability in biomarker distributions. Such differences are exemplified by the triterpenoids (as seen in m/z 191 chromatograms from GC-MS and GC-MS/MS analyses) where the dominant component fluctuates from a 17{alpha}(h),21{beta}(H)-30-norhopane to 28,30-l8{alpha}(H)-bisnorhopane to 20S and 20R danunar-13(17)-enes. Some components are dominant in one interval, but are not detected in others, suggesting discrete stratigraphic variations in the biomarker characteristics of the Moreno. Similar discrepancies in biomarker distributions are evident in the aliphatic hydrocarbons of the suite of oils. The three petroleums reservoired in the San Carlos sandstone member of the Lodo Formation which directly overlies the Moreno, reflect biomarker contributions from a Moreno source, including compound distributions, and the occurrence of both alkanes (e.g., 28.30-bisnorhopane) and alkenes (e.g.. danunarenes and diasterenes).« less

Highly sensitive measurement of whole blood chromium by inductively coupled plasma mass spectrometry.

PubMed

Cieslak, Wendy; Pap, Kathleen; Bunch, Dustin R; Reineks, Edmunds; Jackson, Raymond; Steinle, Roxanne; Wang, Sihe

2013-02-01

Chromium (Cr), a trace metal element, is implicated in diabetes and cardiovascular disease. A hypochromic state has been associated with poor blood glucose control and unfavorable lipid metabolism. Sensitive and accurate measurement of blood chromium is very important to assess the chromium nutritional status. However, interferents in biological matrices and contamination make the sensitive analysis challenging. The primary goal of this study was to develop a highly sensitive method for quantification of total Cr in whole blood by inductively coupled plasma mass spectrometry (ICP-MS) and to validate the reference interval in a local healthy population. This method was developed on an ICP-MS with a collision/reaction cell. Interference was minimized using both kinetic energy discrimination between the quadrupole and hexapole and a selective collision gas (helium). Reference interval was validated in whole blood samples (n=51) collected in trace element free EDTA tubes from healthy adults (12 males, 39 females), aged 19-64 years (38.8±12.6), after a minimum of 8 h fasting. Blood samples were aliquoted into cryogenic vials and stored at -70 °C until analysis. The assay linearity was 3.42 to 1446.59 nmol/L with an accuracy of 87.7 to 99.8%. The high sensitivity was achieved by minimization of interference through selective kinetic energy discrimination and selective collision using helium. The reference interval for total Cr using a non-parametric method was verified to be 3.92 to 7.48 nmol/L. This validated ICP-MS methodology is highly sensitive and selective for measuring total Cr in whole blood. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. Published by Elsevier Inc. All rights reserved.

Influence of waveform and current direction on short-interval intracortical facilitation: a paired-pulse TMS study.

PubMed

Delvendahl, Igor; Lindemann, Hannes; Jung, Nikolai H; Pechmann, Astrid; Siebner, Hartwig R; Mall, Volker

2014-01-01

Transcranial magnetic stimulation (TMS) of the human primary motor hand area (M1-HAND) can produce multiple descending volleys in fast-conducting corticospinal neurons, especially so-called indirect waves (I-waves) resulting from trans-synaptic excitation. Facilitatory interaction between these I-waves can be studied non-invasively using a paired-pulse paradigm referred to as short-interval intracortical facilitation (SICF). We examined whether SICF depends on waveform and current direction of the TMS pulses. In young healthy volunteers, we applied single- and paired-pulse TMS to M1-HAND. We probed SICF by pairs of monophasic or half-sine pulses at suprathreshold stimulation intensity and inter-stimulus intervals (ISIs) between 1.0 and 5.0 ms. For monophasic paired-pulse stimulation, both pulses had either a posterior-anterior (PA) or anterior-posterior (AP) current direction (AP-AP or PA-PA), whereas current direction was reversed between first and second pulse for half-sine paired-pulse stimulation (PA-AP and AP-PA). Monophasic AP-AP stimulation resulted in stronger early SICF at 1.4 ms relative to late SICF at 2.8 and 4.4 ms, whereas monophasic PA-PA stimulation produced SICF of comparable size at all three peaks. With half-sine stimulation the third SICF peak was reduced for PA-AP current orientation compared with AP-PA. SICF elicited using monophasic as well as half-sine pulses is affected by current direction at clearly suprathreshold intensities. The impact of current orientation is stronger for monophasic compared with half-sine pulses. The direction-specific effect of paired-pulse TMS on the strength of early versus late SICF shows that different cortical circuits mediate early and late SICF. Copyright © 2014 Elsevier Inc. All rights reserved.

Anticipatory and compensatory postural adjustments in individuals with multiple sclerosis in response to external perturbations.

PubMed

Aruin, Alexander S; Kanekar, Neeta; Lee, Yun-Ju

2015-03-30

Deficit in balance control is a common and often an initial disabling symptom of multiple sclerosis (MS). The aim of the study was to investigate the organization of anticipatory and compensatory postural adjustments in individuals with MS dealing with external perturbations. Ten individuals with MS and ten age-and-gender matched healthy controls were exposed to external perturbations applied at the shoulder level. The perturbations were either predictable or unpredictable as subjects stood with eyes open or closed. Electrical activity of six leg and trunk muscles as well as displacements of the center of pressure (COP) were recorded and quantified within the time intervals typical of anticipatory (APAs) and compensatory (CPAs) postural adjustments. Individuals with MS demonstrated delayed anticipatory onsets of muscle activity and smaller anticipatory COP displacements as compared to healthy control subjects. The deficiency of the APAs was associated with increased displacements of the COP during the balance restoration phase. The results demonstrate the underlying impairment in anticipatory postural control of individuals with MS. The study outcome provides a background for development of rehabilitation strategies focused on balance restoration in people with MS. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Health status, stress and life satisfaction in a community population with MS.

PubMed

Patten, Scott B; Williams, Jeanne V A; Lavorato, Dina H; Berzins, Sandy; Metz, Luanne M; Bulloch, Andrew G M

2012-03-01

Community-based studies can describe health status and related variables in people with Multiple Sclerosis (MS) while avoiding biases introduced by help-seeking in specific clinical settings. To describe general health status, stress perceptions and life satisfaction in people with MS, in comparison to those with other types of disabilities. The Participation and Activity Limitation Survey (PALS) was a post-censual survey conducted by Statistics Canada in association with the 2006 Canadian Census. PALS collected data from a random sample of n = 22,513 respondents identified as having health-related impairments. Frequencies and quartiles as well as mean values, along with associated 95% confidence intervals, were calculated in the analysis. PALS identified 245 individuals with MS. Health status, both perceived and when weighted for societal preference, was markedly lower than that of other disabled groups. No differences in self-perceived stress were seen. People with MS reported lower levels of satisfaction with their health but slightly higher levels of satisfaction with their family and friends. People with MS report lower levels of general health status and more impairment than those with other disabling conditions. Higher levels of satisfaction with friends and family may reflect psychological adaptation to the illness.

Intracellular Calcium and the Mechanism of Anodal Supernormal Excitability in Langendorff Perfused Rabbit Ventricles

PubMed Central

Joung, Boyoung; Park, Hyung-Wook; Maruyama, Mitsunori; Tang, Liang; Song, Juan; Han, Seongwook; Piccirillo, Gianfranco; Weiss, James N.; Lin, Shien-Fong; Chen, Peng-Sheng

2012-01-01

Background Anodal stimulation hyperpolarizes cell membrane and increases intracellular Ca2+ (Cai) transient. This study tested the hypothesis that The maximum slope of Cai decline (–(dCai/dt)max) corresponds to the timing of anodal dip on the strength-interval curve and the initiation of repetitive responses and ventricular fibrillation (VF) after a premature stimulus (S2). Methods and Results We simultaneously mapped membrane potential (Vm) and Cai in 23 rabbit ventricles. A dip was observed on the anodal strength-interval curve. During the anodal dip, ventricles were captured by anodal break excitation directly under the S2 electrode. The Cai following anodal stimuli is larger than that following cathodal stimuli. The S1-S2 intervals of the anodal dip (203 ± 10 ms) coincided with the -(dCai/dt)max (199 ± 10 ms, p=NS). BAPTA-AM (n=3), INCX inhibition by low extracellular Na+ (n=3), and combined ryanodine and thapsigargin infusion (n=2) eliminated the anodal supernormality. Strong S2 during the relative refractory period (n=5) induced 29 repetitive responses and 10 VF episodes. The interval between S2 and the first non-driven beat was coincidental with the time of -(dCai/dt)max. Conclusions Larger Cai transient and INCX activation induced by anodal stimulation produces anodal supernormality. Time of maximum INCX activation is coincidental to the induction of non- driven beats from the Cai sinkhole after a strong premature stimulation. PMID:21301131

QT and JT dispersion and cardiac performance in children with neonatal Bartter syndrome: a pilot study.

PubMed

Hacihamdioglu, Duygu Ovunc; Fidanci, Kursat; Kilic, Ayhan; Gok, Faysal; Topaloglu, Rezan

2013-10-01

QT dispersion and JT dispersion are simple noninvasive arrhythmogenic markers that can be used to assess the homogeneity of cardiac repolarization. The aim of this study was to assess QT and JT dispersion and their relation with left ventricular systolic and diastolic functions in children with Bartter syndrome (BS). Nine neonatal patients with BS (median age 9.7 years) and 20 controls (median age 8 years) were investigated at rest. Both study and control subjects underwent electrocardiography (ECG) in which the interval between two R waves and QT intervals, corrected QT, QT dispersion, corrected QT dispersion, JT, corrected JT, JT dispersion and corrected JT dispersion were measured with 12-lead ECG. Two-dimensional, Doppler echocardiographic examinations were performed. Patients and controls did not differ for gender and for serum levels of potassium, magnesium, and calcium (p > 0.05). Both study and control subjects had normal echocardiographic examination and baseline myocardial performance indexes. The QT dispersion and JT dispersion were significantly prolonged in patients with BS compared to those of the controls {37.5 ms [interquartile range (IQR) 32.5-40] vs. 25.5 ms (IQR 20-30), respectively, p = 0.014 and 37.5 ms (IQR 27.5-40) vs. 22.5 ms (IQR 20-30), respectively, p = 0.003}. Elevated QT and JT dispersion during asymptomatic and normokalemic periods may be risk factors for the development of cardiac complications and arrhythmias in children with BS. In these patients the need for systematic cardiac screening and management protocol is extremely important for effective prevention.

High Intensity Interval Training Reduces the Levels of Serum Inflammatory Cytokine on Women with Metabolic Syndrome.

PubMed

Steckling, F M; Farinha, J B; Santos, D L D; Bresciani, G; Mortari, J A; Stefanello, S T; Courtes, A A; Duarte, T; Duarte, M M M F; Moresco, R N; Cardoso, M S; Soares, F A A

2016-11-01

Objectives: This study investigate the effects of a high intensity interval training (HIIT) and 2 weeks of detraining in functional and body composition parameters, lipoproteins, glucose metabolismand inflammation markers in postmenopausal women with metabolic syndrome (MS). Design: 17 untrained women with MS underwent a HIIT program for 12 weeks. Methods: The training was performed in treadmills, 3 days per week, with intensity ranging from 70-90% of the maximum heart rate (HR max ) and 2 weeks untrained (inactive). Functional and body composition parameters were evaluated before and after the training, while maximal oxygen uptake, lipoprotein and inflammation markers were analyzed before, after training and also in detraining. Results: The HITT program resulted in changesparameters as glucose, HbA1cand NOx after training. In addition, a reduction in pro-inflammatory interleukins and an increase in IL-10 after the HIIT program were found. However, an increase in plasma levels of lipoprotein was found and body composition parameters remain unaltered.Besides, only 2 weeks of detraining are able to revert the effects on inflammatory parameters afforded by the HIIT program. Conclusions: The HIIT program used here positively affected inflammatory profile and other parameters, as glucose, HbA1cand NOx, on postmenopausal women with MS. Moreover, 2 weeks of detraining can reverse the beneficial effects of HIIT program. Our results point out the necessity to aply acontinuous HITT program, in order maintain the benefits detected, to post menopausal women with MS. © Georg Thieme Verlag KG Stuttgart · New York.

MicroPET/CT Imaging of an Orthotopic Model of Human Glioblastoma Multiforme and Evaluation of Pulsed Low-Dose Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Sean S.; Chunta, John L.; Robertson, John M.

2011-07-01

Purpose: Glioblastoma multiforme (GBM) is an aggressive tumor that typically causes death due to local progression. To assess a novel low-dose radiotherapy regimen for treating GBM, we developed an orthotopic murine model of human GBM and evaluated in vivo treatment efficacy using micro-positron-emission tomography/computed tomography (microPET/CT) tumor imaging. Methods: Orthotopic GBM xenografts were established in nude mice and treated with standard 2-Gy fractionation or 10 0.2-Gy pulses with 3-min interpulse intervals, for 7 consecutive days, for a total dose of 14 Gy. Tumor growth was quantified weekly using the Flex Triumph (GE Healthcare/Gamma Medica-Ideas, Waukesha, WI) combined PET-single-photon emission CTmore » (SPECT)-CT imaging system and necropsy histopathology. Normal tissue damage was assessed by counting dead neural cells in tissue sections from irradiated fields. Results: Tumor engraftment efficiency for U87MG cells was 86%. Implanting 0.5 x 10{sup 6} cells produced a 50- to 70-mm{sup 3} tumor in 10 to 14 days. A significant correlation was seen between CT-derived tumor volume and histopathology-measured volume (p = 0.018). The low-dose 0.2-Gy pulsed regimen produced a significantly longer tumor growth delay than standard 2-Gy fractionation (p = 0.045). Less normal neuronal cell death was observed after the pulsed delivery method (p = 0.004). Conclusion: This study successfully demonstrated the feasibility of in vivo brain tumor imaging and longitudinal assessment of tumor growth and treatment response with microPET/CT. Pulsed radiation treatment was more efficacious than the standard fractionated treatment and was associated with less normal tissue damage.« less

MicroPET/CT imaging of an orthotopic model of human glioblastoma multiforme and evaluation of pulsed low-dose irradiation.

PubMed

Park, Sean S; Chunta, John L; Robertson, John M; Martinez, Alvaro A; Oliver Wong, Ching-Yee; Amin, Mitual; Wilson, George D; Marples, Brian

2011-07-01

Glioblastoma multiforme (GBM) is an aggressive tumor that typically causes death due to local progression. To assess a novel low-dose radiotherapy regimen for treating GBM, we developed an orthotopic murine model of human GBM and evaluated in vivo treatment efficacy using micro-positron-emission tomography/computed tomography (microPET/CT) tumor imaging. Orthotopic GBM xenografts were established in nude mice and treated with standard 2-Gy fractionation or 10 0.2-Gy pulses with 3-min interpulse intervals, for 7 consecutive days, for a total dose of 14 Gy. Tumor growth was quantified weekly using the Flex Triumph (GE Healthcare/Gamma Medica-Ideas, Waukesha, WI) combined PET-single-photon emission CT (SPECT)-CT imaging system and necropsy histopathology. Normal tissue damage was assessed by counting dead neural cells in tissue sections from irradiated fields. Tumor engraftment efficiency for U87MG cells was 86%. Implanting 0.5 × 10(6) cells produced a 50- to 70-mm(3) tumor in 10 to 14 days. A significant correlation was seen between CT-derived tumor volume and histopathology-measured volume (p = 0.018). The low-dose 0.2-Gy pulsed regimen produced a significantly longer tumor growth delay than standard 2-Gy fractionation (p = 0.045). Less normal neuronal cell death was observed after the pulsed delivery method (p = 0.004). This study successfully demonstrated the feasibility of in vivo brain tumor imaging and longitudinal assessment of tumor growth and treatment response with microPET/CT. Pulsed radiation treatment was more efficacious than the standard fractionated treatment and was associated with less normal tissue damage. Copyright © 2011 Elsevier Inc. All rights reserved.

Pulsed Versus Conventional Radiation Therapy in Combination With Temozolomide in a Murine Orthotopic Model of Glioblastoma Multiforme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, David Y.; Chunta, John L.; Park, Sean S.

Purpose: To evaluate the efficacy of pulsed low-dose radiation therapy (PLRT) combined with temozolomide (TMZ) as a novel treatment approach for radioresistant glioblastoma multiforme (GBM) in a murine model. Methods and Materials: Orthotopic U87MG hGBM tumors were established in Nu-Foxn1{sup nu} mice and imaged weekly using a small-animal micropositron emission tomography (PET)/computed tomography (CT) system. Tumor volume was determined from contrast-enhanced microCT images and tumor metabolic activity (SUVmax) from the F18-FDG microPET scan. Tumors were irradiated 7 to 10 days after implantation with a total dose of 14 Gy in 7 consecutive days. The daily treatment was given as amore » single continuous 2-Gy dose (RT) or 10 pulses of 0.2 Gy using an interpulse interval of 3 minutes (PLRT). TMZ (10 mg/kg) was given daily by oral gavage 1 hour before RT. Tumor vascularity and normal brain damage were assessed by immunohistochemistry. Results: Radiation therapy with TMZ resulted in a significant 3- to 4-week tumor growth delay compared with controls, with PLRT+TMZ the most effective. PLRT+TMZ resulted in a larger decline in SUVmax than RT+TMZ. Significant differences in survival were evident. Treatment after PLRT+TMZ was associated with increased vascularization compared with RT+TMZ. Significantly fewer degenerating neurons were seen in normal brain after PLRT+TMZ compared with RT+TMZ. Conclusions: PLRT+TMZ produced superior tumor growth delay and less normal brain damage when compared with RT+TMZ. The differential effect of PLRT on vascularization may confirm new treatment avenues for GBM.« less

Blunted day-night changes in luteinizing hormone pulse frequency in girls with obesity: the potential role of hyperandrogenemia.

PubMed

Collins, Jessicah S; Beller, Jennifer P; Burt Solorzano, Christine; Patrie, James T; Chang, R Jeffrey; Marshall, John C; McCartney, Christopher R

2014-08-01

Puberty is marked by sleep-associated changes in LH pulse frequency and amplitude. Early pubertal girls with obesity exhibit blunted day-to-night changes in LH secretion; whether this occurs in late pubertal obese girls is unknown. The objective of the study was to test two hypotheses: 1) blunted day-to-night changes in LH secretion occur in both early and late pubertal obese girls, and 2) such alterations are specifically associated with hyperandrogenemia. This was a cross-sectional analysis. The study was conducted at a clinical research center. Twenty-seven early pubertal, premenarcheal girls (12 of whom were obese) and 63 late pubertal (postmenarcheal) girls (27 of whom were obese) participated in the study. Blood samples were taken every 10 minutes from 7:00 pm to 7:00 am. Change in LH pulse frequency [LH interpulse interval (IPI)] from daytime hours (7:00 pm-11:00 pm, while awake) to nighttime hours (11:00 pm to 7:00 am, while generally asleep). Both nonobese and obese postmenarcheal girls demonstrated significant day-to-night decreases in LH pulse frequency (IPI increases of 33% and 16%, respectively), but day-to-night changes were blunted in obese girls (P = .004, obese vs nonobese). Day-to-night LH pulse frequency decreased significantly in postmenarcheal obese subjects with normal T concentrations (26% IPI increase) but not in those with hyperandrogenemia. Similar differences were evident for LH pulse amplitude. Nonobese and obese early pubertal girls exhibited nonsignificant differences in day-night LH pulse frequency (day to night IPI increase of 26% vs decrease of 1%, respectively). Day-to-night changes in LH pulse secretion are blunted in postmenarcheal obese adolescent girls. This phenomenon may in part reflect hyperandrogenemia.

Simultaneous Wireless Power Transfer and Data Communication Using Synchronous Pulse-Controlled Load Modulation.

PubMed

Mao, Shitong; Wang, Hao; Zhu, Chunbo; Mao, Zhi-Hong; Sun, Mingui

2017-10-01

Wireless Power Transfer (WPT) and wireless data communication are both important problems of research with various applications, especially in medicine. However, these two problems are usually studied separately. In this work, we present a joint study of both problems. Most medical electronic devices, such as smart implants, must have both a power supply to allow continuous operation and a communication link to pass information. Traditionally, separate wireless channels for power transfer and communication are utilized, which complicate the system structure, increase power consumption and make device miniaturization difficult. A more effective approach is to use a single wireless link with both functions of delivering power and passing information. We present a design of such a wireless link in which power and data travel in opposite directions. In order to aggressively miniaturize the implant and reduce power consumption, we eliminate the traditional multi-bit Analog-to-Digital Converter (ADC), digital memory and data transmission circuits all together. Instead, we use a pulse stream, which is obtained from the original biological signal, by a sigma-delta converter and an edge detector, to alter the load properties of the WPT channel. The resulting WPT signal is synchronized with the load changes therefore requiring no memory elements to record inter-pulse intervals. We take advantage of the high sensitivity of the resonant WPT to the load change, and the system dynamic response is used to transfer each pulse. The transient time of the WPT system is analyzed using the coupling mode theory (CMT). Our experimental results show that the memoryless approach works well for both power delivery and data transmission, providing a new wireless platform for the design of future miniaturized medical implants.

Safety and efficacy of dual-wavelength laser (1064 + 595 nm) for treatment of non-treated port-wine stains.

PubMed

Wang, T; Chen, D; Yang, J; Ma, G; Yu, W; Lin, X

2018-02-01

Patients with port-wine stain (PWS) suffer physically and psychologically because of the high incidence (0.3%-0.5%) of the disease. Pulsed-dye laser (PDL) at 595 nm is the gold standard of the treatment for PWS. Nevertheless, clinicians intend to determine whether the dual-wavelength laser (DWL; 595-nm PDL + 1064-nm Nd:YAG) is an adequate choice in the treatment of non-treated PWS. This study is the first prospective within-patient controlled research seeking to investigate the safety and efficacy of DWL for the treatment of non-treated PWS. A total of 61 patients with non-treated flat facial PWS, who were treated using the Cynergy laser system in our clinic, were included in this study. Each PWS lesion was divided into two adjacent test treatment sites of similar size and colour. The two sites were randomly assigned to PDL or DWL treatment in a blinded manner of participants. In each case, two sets of treatment parameters were used: (i) 595-nm PDL and (ii) 595-nm PDL + 1064-nm Nd:YAG. Both had a 10 mm spot size, an epidermal cooling system and 1-s interpulse interval between two pulses. Clinical efficacy and safety outcomes were evaluated by visual assessment 2 months after treatment. Comparison by visual evaluation suggests that the responses of non-treated PWS to treatment by PDL and DWL were not significantly different. Moreover, three patients developed scarring after DWL treatment. Compared with PDL, DWL exhibits a higher risk of potential scarring and has no advantage in efficacy of treating non-treated PWS. © 2017 European Academy of Dermatology and Venereology.

Mathematical modeling and spectrum analysis of the physiological patello-femoral pulse train produced by slow knee movement.

PubMed

Zhang, Y T; Frank, C B; Rangayyan, R M; Bell, G D

1992-09-01

Analysis of vibration signals emitted by the knee joint has the potential for the development of a noninvasive procedure for the diagnosis and monitoring of knee pathology. In order to obtain as much information as possible from the power density spectrum of the knee vibration signal, it is necessary to identify the physiological factors (or physiologically relevant parameters) that shape the spectrum. This paper presents a mathematical model for knee vibration signals, in particular the physiological patello-femoral pulse (PFP) train produced by slow knee movement. It demonstrates through the mathematical model that the repetition rate of the physiological PFP train introduces repeated peaks in the power spectrum, and that it affects the spectrum mainly at low frequencies. The theoretical results also show that the spectral peaks at multiples of the PFP repetition rate become more evident when the variance of the interpulse interval (IPI) is small, and that these spectral peaks shift toward higher frequencies with increasing PFP repetition rates. To evaluate the mathematical model, a simulation algorithm was developed, which generates PFP signals with adjustable repetition rate and IPI variance. Signals generated by simulation were seen to possess representative spectral characteristics typically observed in physiological PFP signals. This simulation procedure allows an interactive examination of several factors which affect the PFP train spectrum. Finally, in vivo measurements of physiological PFP signals of normal volunteers are presented. Results of simulations and analysis of signals recorded from human subjects support the mathematical model's prediction that the IPI statistics play a very significant role in determining the low-end power spectrum of the physiological PFP signal.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of torsades de pointes in older patients with drug-associated long QT syndrome: a case-control study.

PubMed

Goutelle, Sylvain; Sidolle, Elodie; Ducher, Michel; Caron, Jacques; Timour, Quadiri; Nony, Patrice; Gouraud, Aurore

2014-08-01

Many elderly patients are routinely exposed to drugs that may prolong the cardiac QT interval and cause Torsades de pointes (TdP). However, predictors of TdP in patients with drug-associated long QT syndrome (LQTS) are not fully understood, especially in the geriatric population. The objective of this study was to identify risk factors of TdP in elderly patients with drug-associated LQTS. In this retrospective, case-control study, documented reports of drug-associated LQTS plus TdP (n = 125) and LQTS without TdP (n = 81) in patients ≥65 years of age were retrieved from the French Pharmacovigilance Database over a 10-year period. Available clinical, biological, and drug therapy data were compared in the two groups and logistic regression was performed to identify significant predictors of TdP. The uncorrected QT interval was significantly longer in patients with TdP than in patients without TdP (577 ± 79 vs. 519 ± 68 ms; p = 0.0001). The number of drugs with a known risk of TdP administered to each patient was not a predictor of arrhythmia, nor was female gender. Logistic regression analysis identified the uncorrected QT interval as the only significant predictor of TdP. The receiver operating characteristic curve analysis was characterized by an area under the curve of 0.77 (95 % confidence interval 0.64-0.88) and a QT cutoff of 550 ms. The uncorrected QT interval was significantly associated with the probability of TdP in elderly patients with acquired, drug-associated LQTS.

Obesity during childhood and adolescence increases susceptibility to multiple sclerosis after accounting for established genetic and environmental risk factors.

PubMed

Gianfrancesco, Milena A; Acuna, Brigid; Shen, Ling; Briggs, Farren B S; Quach, Hong; Bellesis, Kalliope H; Bernstein, Allan; Hedstrom, Anna K; Kockum, Ingrid; Alfredsson, Lars; Olsson, Tomas; Schaefer, Catherine; Barcellos, Lisa F

2014-01-01

To investigate the association between obesity and multiple sclerosis (MS) while accounting for established genetic and environmental risk factors. Participants included members of Kaiser Permanente Medical Care Plan, Northern California Region (KPNC) (1235 MS cases and 697 controls). Logistic regression models were used to estimate odds ratios (ORs) with 95% confidence intervals (95% CI). Body mass index (BMI) or body size was the primary predictor of each model. Both incident and prevalent MS cases were studied. In analyses stratified by gender, being overweight at ages 10 and 20 were associated with MS in females (p<0.01). Estimates trended in the same direction for males, but were not significant. BMI in 20s demonstrated a linear relationship with MS (p-trend=9.60×10(-4)), and a twofold risk of MS for females with a BMI≥30kg/m(2) was observed (OR=2.15, 95% CI 1.18, 3.92). Significant associations between BMI in 20s and MS in males were not observed. Multivariate modelling demonstrated that significant associations between BMI or body size with MS in females persisted after adjusting for history of infectious mononucleosis and genetic risk factors, including HLA-DRB1*15:01 and established non-HLA risk alleles. Results show that childhood and adolescence obesity confer increased risk of MS in females beyond established heritable and environmental risk factors. Strong evidence for a dose-effect of BMI in 20s and MS was observed. The magnitude of BMI association with MS is as large as other known MS risk factors. Copyright © 2014 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

Obesity during childhood and adolescence increases susceptibility to multiple sclerosis after accounting for established genetic and environmental risk factors

PubMed Central

Gianfrancesco, Milena A.; Acuna, Brigid; Shen, Ling; Briggs, Farren B.S.; Quach, Hong; Bellesis, Kalliope H.; Bernstein, Allan; Hedstrom, Anna K.; Kockum, Ingrid; Alfredsson, Lars; Olsson, Tomas; Schaefer, Catherine; Barcellos, Lisa F.

2014-01-01

Objective To investigate the association between obesity and multiple sclerosis (MS) while accounting for established genetic and environmental risk factors. Methods Participants included members of Kaiser Permanente Medical Care Plan, Northern California Region (KPNC) (1,235 MS cases and 697 controls). Logistic regression models were used to estimate odds ratios (ORs) with 95% confidence intervals (95% CI). Body mass index (BMI) or body size was the primary predictor of each model. Both incident and prevalent MS cases were studied. Results In analyses stratified by gender, being overweight at age 10 and 20 were associated with MS in females (p<0.01). Estimates trended in the same direction for males, but were not significant. BMI in 20’s demonstrated a linear relationship with MS (p-trend=9.60 × 10−4), and a twofold risk of MS for females with a BMI ≥ 30 kg/m2 was observed (OR = 2.15, 95% CI 1.18, 3.92). Significant associations between BMI in 20’s and MS in males were not observed. Multivariate modeling demonstrated that significant associations between BMI or body size with MS in females persisted after adjusting for history of infectious mononucleosis and genetic risk factors, including HLA-DRB1*15:01 and established non-HLA risk alleles. Interpretation Results show that childhood and adolescence obesity confer increased risk of MS in females beyond established heritable and environmental risk factors. Strong evidence for a dose-effect of BMI in 20’s and MS was observed. The magnitude of BMI association with MS is as large as other known MS risk factors. PMID:25263833

Comparison of corrected QT interval as measured on electroencephalography versus 12-lead electrocardiography in children with a history of syncope.

PubMed

Massey, Shavonne L; Wise, Marshall S; Madan, Nandini; Carvalho, Karen; Khurana, Divya; Legido, Agustin; Valencia, Ignacio

2011-11-01

Long QT syndrome can present with neurological manifestations, including syncope and seizure-like activity. These patients often receive an initial neurologic evaluation, including electroencephalography (EEG). Our previous retrospective study suggested an increased prevalence of prolonged corrected QT interval (QTc) measured during the EEG of patients with syncope. The aim of the current study is to assess the accuracy of the EEG QTc reading compared with the nonsimultaneous 12-lead electrocardiography (ECG) in children with syncope. Abnormal QTc was defined as ≥450 ms in boys, ≥460 ms in girls. Forty-two children were included. There was no significant correlation between QTc readings in the EEG and ECG. EEG failed to identify 2 children with prolonged QTc in the ECG and overestimated the QTc in 3 children with normal QTc in the ECG. This study suggests that interpretation of the QTc segment during an EEG is limited. Further studies with simultaneous EEG and 12-lead ECG are warranted.

Potential use of hydrocarbons for aging Lucilia sericata blowfly larvae to establish the postmortem interval.

PubMed

Moore, Hannah E; Adam, Craig D; Drijfhout, Falko P

2013-03-01

Previous studies on Diptera have shown the potential for the use of cuticular hydrocarbons' analysis in the determination of larval age and hence the postmortem interval (PMI) for an associated cadaver. In this work, hydrocarbon compounds, extracted daily until pupation from the cuticle of the blowfly Lucilia sericata (Diptera: Calliphoridae), have been analyzed using gas chromatography-mass spectrometry (GC-MS). The results show distinguishing features within the hydrocarbon profile over the period of the larvae life cycle, with significant chemical changes occurring from the younger larvae to the postfeeding larvae. Further interpretation of the chromatograms using principal component analysis revealed a strong correlation between the magnitudes of particular principal components and time. This outcome suggests that, under the conditions of this study, the cuticular hydrocarbons evolve in a systematic fashion with time, thus supporting the potential for GC-MS analysis as a tool for establishing PMI where such a species is present. © 2012 American Academy of Forensic Sciences.

Flecainide attenuates rate adaptation of ventricular repolarization in guinea-pig heart.

PubMed

Osadchii, Oleg E

2016-01-01

Flecainide is class Ic antiarrhythmic agent that was found to increase the risk of sudden cardiac death. Arrhythmic responses to flecainide could be precipitated by exercise, suggesting a role played by inappropriate rate adaptation of ventricular repolarization. This study therefore examined flecainide effect on adaptation of the QT interval and ventricular action potential duration (APD) to abrupt reductions of the cardiac cycle length. ECG and ventricular epicardial and endocardial monophasic APD were recorded in isolated, perfused guinea-pig heart preparations upon a sustained cardiac acceleration (rapid pacing for 30 s), and following a single perturbation of the cycle length evoked by extrasystolic stimulation. Sustained increase in heart rate was associated with progressive bi-exponential shortening of the QT interval and APD. Flecainide prolonged ventricular repolarization, delayed its rate adaptation, and decreased the amplitude of QT interval and APD shortening upon rapid cardiac pacing. During extrasystolic stimulation, flecainide attenuated APD shortening in premature ventricular beats, with effect being greater upon using a longer basic drive cycle length (S1-S1=550 ms versus S1-S1=300 ms). Flecainide-induced arrhythmia may be partly accounted for by attenuated adaptation of ventricular repolarization to sudden changes in cardiac cycle length provoked by transient tachycardia or ectopic beats.

Noninvasive Fetal ECG: the PhysioNet/Computing in Cardiology Challenge 2013.

PubMed

Silva, Ikaro; Behar, Joachim; Sameni, Reza; Zhu, Tingting; Oster, Julien; Clifford, Gari D; Moody, George B

2013-03-01

The PhysioNet/CinC 2013 Challenge aimed to stimulate rapid development and improvement of software for estimating fetal heart rate (FHR), fetal interbeat intervals (FRR), and fetal QT intervals (FQT), from multichannel recordings made using electrodes placed on the mother's abdomen. For the challenge, five data collections from a variety of sources were used to compile a large standardized database, which was divided into training, open test, and hidden test subsets. Gold-standard fetal QRS and QT interval annotations were developed using a novel crowd-sourcing framework. The challenge organizers used the hidden test subset to evaluate 91 open-source software entries submitted by 53 international teams of participants in three challenge events, estimating FHR, FRR, and FQT using the hidden test subset, which was not available for study by participants. Two additional events required only user-submitted QRS annotations to evaluate FHR and FRR estimation accuracy using the open test subset available to participants. The challenge yielded a total of 91 open-source software entries. The best of these achieved average estimation errors of 187bpm 2 for FHR, 20.9 ms for FRR, and 152.7 ms for FQT. The open data sets, scoring software, and open-source entries are available at PhysioNet for researchers interested on working on these problems.

Active/passive mode-locked laser oscillator

DOEpatents

Fountain, William D.; Johnson, Bertram C.

1977-01-01

A Q-switched/mode-locked Nd:YAG laser oscillator employing simultaneous active (electro-optic) and passive (saturable absorber) loss modulation within the optical cavity is described. This "dual modulation" oscillator can produce transform-limited pulses of duration ranging from about 30 psec to about 5 nsec with greatly improved stability compared to other mode-locked systems. The pulses produced by this system lack intrapulse frequency or amplitude modulation, and hence are idealy suited for amplification to high energies and for other applications where well-defined pulses are required. Also, the pulses of this system have excellent interpulse characteristics, wherein the optical noise between the individual pulses of the pulse train has a power level well below the power of the peak pulse of the train.

Characteristics of soft x-ray and extreme ultraviolet (XUV) emission from laser-produced highly charged rhodium ions

NASA Astrophysics Data System (ADS)

Barte, Ellie Floyd; Hara, Hiroyuki; Tamura, Toshiki; Gisuji, Takuya; Chen, When-Bo; Lokasani, Ragava; Hatano, Tadashi; Ejima, Takeo; Jiang, Weihua; Suzuki, Chihiro; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Sasaki, Akira; Higashiguchi, Takeshi; Limpouch, Jiří

2018-05-01

We have characterized the soft x-ray and extreme ultraviolet (XUV) emission of rhodium (Rh) plasmas produced using dual pulse irradiation by 150-ps or 6-ns pre-pulses, followed by a 150-ps main pulse. We have studied the emission enhancement dependence on the inter-pulse time separation and found it to be very significant for time separations less than 10 ns between the two laser pulses when using 6-ns pre-pulses. The behavior using a 150-ps pre-pulse was consistent with such plasmas displaying only weak self-absorption effects in the expanding plasma. The results demonstrate the advantage of using dual pulse irradiation to produce the brighter plasmas required for XUV applications.

Experimental evaluation of battery cells for space-based radar application

NASA Technical Reports Server (NTRS)

Maskell, Craig A.; Metcalfe, John R.

1994-01-01

A test program was conducted to characterize five space-quality nickel-hydrogen (NiH2) battery cells. A subset of those tests was also done on five commercial nickel-cadmium (NiCd) cells, for correlation to the characteristics of an Energy Storage Unit Simulator. The test program implemented the recommendations of a 1991 study, as reported to IECEC-92. The findings of the tests are summarized, and expected impacts on the performance of the electrical power system (EPS) of a large space-based radar (SBR) surveillance satellite are derived. The main characteristics examined and compared were terminal voltage (average and transient) and capacity through discharge, equivalent series resistance, derived inductance and capacitance, charge return efficiency, and inter-pulse charge effectiveness.

A search for UHE cosmic ray from the Crab pulsar/nebula

NASA Astrophysics Data System (ADS)

Alexandreas, D. E.; Berley, D.; Biller, S. D.; Burman, R. L.; Cady, D. R.; Chang, C. Y.; Dingus, B. L.; Dion, C.; Dion, G. M.; Ellsworth, E. W.; Goodman, J. A.; Haines, T. J.; Hoffman, C. M.; Krakauer, D. A.; Kwok, P. W.; Lloyd-Evans, J.; Lu, X.-Q.; Nagle, D. A.; Potter, M. E.; Sandberg, V. D.; Stark, M. J.; Vishwanath, P. R.; Yodh, G. B.; Zhang, W. P.

1991-04-01

A preliminary search is made for continuously pulsed, and burst, emission from the Crab pulsar or its nebula at ultra-high energies using the CYGNUS air shower experiment. No evidence is found for pulsed emission over the entire data set of 1,075 days searched. A 90% confidence upper limit for the flux of cosmic rays at the interpulse phase is 6.9×10-14 cm-2s-1 above 50 TeV. A single day (JD=2447644.5,UTC=66700s to JD=2447645.5,UTC=11200s), is found to have a 4.1 σ excess corresponding to a chance probability of 2.2%; no evidence of the pulsar period is found on this day.

Moxifloxacin-induced QTc interval prolongations in healthy male Japanese and Caucasian volunteers: a direct comparison in a thorough QT study

PubMed Central

Morganroth, Joel; Wang, Yaning; Thorn, Michael; Kumagai, Yuji; Harris, Stuart; Stockbridge, Norman; Kleiman, Robert; Shah, Rashmi

2015-01-01

Aim We investigated whether moxifloxacin-induced QTc prolongations in Japanese and Caucasian healthy male volunteers were significantly different. Methods A two period, randomized, crossover, ICH-E14-compliant thorough QT (TQT) study compared placebo-corrected changes in QTc interval from baseline (ΔΔQTcF) and concentration–effect relationships following administration of placebo and 400 mg moxifloxacin to 40 healthy male volunteers from each ethnic population. The point estimates of ΔΔQTcF for each population, and the difference between the two, were calculated at a geometric mean Cmax of moxifloxacin using a linear mixed effects model. The concentration–effect slopes of the two populations were also compared. Equivalence was concluded if the two-sided 90% confidence interval of the difference in ΔΔQTcF was contained within −5 ms to +5 ms limits and the ratio of the slopes was between 0.5 and 2. Results There were no statistically significant differences between the two populations studied, Japanese vs. Caucasians, respectively, for moxifloxacin Cmax (3.27 ± 0.6 vs. 2.98 ± 0.7 µg ml–1), ΔΔQTcF (9.63 ± 1.15 vs. 11.46 ± 1.19 ms at Cmax of 3.07 µg ml–1) and concentration–response slopes (2.58 ± 0.62 vs. 2.34 ± 0.64 ms per µg ml–1). The difference in the two ΔΔQTcF of −1.8 (90% CI −4.6, 0.9) and the ratio of the two slopes (1.1; 90% CI 0.63, 1.82) were within pre-specified equivalence limits. Conclusions Moxifloxacin-induced QTc prolongations did not differ significantly between the Japanese and Caucasian subjects. However, before our findings are more widely generalized, further studies in other populations and with other QT-prolonging drugs are needed to clarify whether inter-ethnic differences in QT sensitivity exist and whether ethnicity of the study population may affect the outcome of a TQT study. PMID:26011050

Tracking recent climate and anthropogenic change in Central America in sediments form the lower fan of the Rio Yaqui, Gulf of California, Mexico

NASA Astrophysics Data System (ADS)

Aiello, I. W.; Ravelo, A. C.; Moraes, R.; Swarzenski, P. W.

2015-12-01

We report the results of preliminary sedimentologic analyses of a ~3.3m long piston core (P13) collected in the lower fan of the Rio Yaqui (Guaymas Basin, Gulf of California; depth, 1859m) by UNAM's (Universidad Nacional Autónoma de México) research ship El Puma in 2014. The core was collected to test the potential for high-resolution reconstructions of basin-scale paleoclimate in the Pacific and the Mesoamerican region. Shipboard and post-cruise analyses include magnetic susceptibility (MS), smear slide counts and laser diffraction particle size analysis. The core is being analyzed for X-Ray Fluorescence (XRF) and color reflectance, and a 210Pb age model is being constructed. Preliminary results show that Rio Yaqui lower fan sediment differs significantly from that in the Guaymas Basin, which is dominantly diatom ooze. The lower ~2m of core P13 show prominent alternations (~10-20cm) between very-fine-grained, clay intervals characterized by higher MS and mixed diatom and clay intervals, with coarser grain size and lower MS values. In contrast, the upper ~1m has distinctive high MS sand turbidites alternating with diatom-rich layers. Previous core studies from nearby ODP Leg 64 site show sedimentation rates of ~1.2 m/ka; as these sites are further away from the Yaqui delta the sedimentation rates for core P13 should be higher possibly recording only the last few hundred years of sedimentation. Clay/diatom cycles in the lower part of the core could record decadal- or ENSO-scale wet/aridity cycles in the Sonoran Mainland. Conversely, the coarser siliciclastic intervals and the diatom layers in the upper part of the core could reflect the last few decades of land usage in the watershed of the Rio Yaqui, the most important river in the state of Sonora, Mexico. These include large modifications to the river's hydrography (e.g. construction of dams and aqueducts), rapidly expanding mass agricultural practices in the region, and increased eutrophication in the Gulf.

Psychiatric diagnoses, medication and risk for disability pension in multiple sclerosis patients; a population-based register study.

PubMed

Brenner, Philip; Alexanderson, Kristina; Björkenstam, Charlotte; Hillert, Jan; Jokinen, Jussi; Mittendorfer-Rutz, Ellenor; Tinghög, Petter

2014-01-01

Psychiatric comorbidity is common among multiple sclerosis (MS) patients. The majority of MS patients of working ages are on disability pension. The aims of this study were to chart the prevalences of psychiatric diagnoses and medications among MS patients of working ages, and to investigate their association with the risk for future disability pension. This nationwide, population-based prospective cohort study includes 10,750 MS patients and 5,553,141 non-MS individuals who in 2005 were aged 17-64 years. Psychiatric diagnoses and medications were identified using nationwide registers. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated adjusting for socio-demographics. Furthermore, a survival analysis with five-year follow-up was performed among the 4,571 MS patients not on disability pension in 2005, with psychiatric diagnoses and medication as risk factors, and disability pension as the outcome. Among MS patients, 35% had been prescribed psychiatric medication compared to 10% of non-MS individuals, adjusted OR 3.72 (95% CI 3.57 to 3.88). Ten percent of MS patients had received a psychiatric diagnosis, compared to 5.7% of non-MS individuals, OR 1.82 (95% CI 1.71 to 1.94). Serotonin reuptake inhibitors (SSRIs), were the most commonly prescribed drugs (17%) among MS patients, while depression (4.8%) was the most common psychiatric diagnosis. In the survival analysis, MS patients with any psychiatric diagnosis had a hazard ratio (HR) of 1.83 (95% CI 1.53 to 2.18) for disability pension compared to other MS patients. MS patients with any psychiatric drug prescription had a HR for disability pension of 2.09 (95% CI 1.84 to 2.33). Psychiatric diagnoses and medications are common among MS patients and adversely affect risk for disability pension. This highlights the importance of correct diagnosis and management of psychiatric comorbidity, in a clinical as well as in a societal perspective.

Cardiac electrical conduction, autonomic activity and biomarker release during recovery from prolonged strenuous exercise in trained male cyclists.

PubMed

Stewart, Glenn M; Kavanagh, Justin J; Koerbin, Gus; Simmonds, Michael J; Sabapathy, Surendran

2014-01-01

Although markers of myocyte injury, electrolyte disturbances and an autonomic imbalance have been reported following exercise, the effect of prolonged strenuous activity on cardiac electrical conduction is not well understood. This study examined atrial and ventricular conduction dynamics during recovery from exercise. Electrocardiographic intervals were obtained from eight highly-trained males before, during recovery (15, 30, 45 and 60 min post-exercise) and 24 h after a prolonged bout of strenuous exercise. Time-domain, frequency-domain and non-linear analyses of the RR, PR and QT intervals were analysed to investigate the effect of exercise on autonomic modulation and cardiac electrical conduction. Serum electrolyte and high-sensitivity cardiac troponin T (hs-cTnT) concentrations were measured before exercise, and after 60 min and 24 h of recovery. The root mean square of the successive differences of RR, PR and QT intervals was significantly reduced during recovery (p < 0.05). Normalised low- and high-frequency power of RR intervals significantly increased and decreased, respectively, during recovery. Approximate entropy of PR and QT intervals, and the QT-variability index significantly increased during recovery. All measures except mean QT interval (pre 422 ± 10 ms vs 24 h post 442 ± 11 ms, p = 0.013) returned to pre-exercise values after 24 h. Serum hs-cTnT was significantly elevated 60 min after exercise (pre 5.2 ± 0.7 ng L(-1) vs 60 min post 27.4 ± 6.2 ng L(-1), p = 0.01) and correlated with exercising heart rate (R(2) = 0.89, p < 0.001). Serum electrolyte concentrations were unchanged (p > 0.05). The results suggest suppressed parasympathetic and/or sustained sympathetic modulation of heart rate during recovery, concomitant with perturbations in atrial and ventricular conduction dynamics. Exercise-induced hs-cTnT release was heart rate dependent.

Channel Equalization for Single Carrier MIMO Underwater Acoustic Communications

DTIC Science & Technology

2010-01-01

II Tx 1 Tx 2 Symbol mapping s1 s2 x1 x2 sa Figure 2: Signalling at the transmitter in Makai05 experiment. fc = 32 kHz and the symbol interval was...frequency was fc = 37.5 kHz and the symbol interval was 0.05ms. The occupied channel bandwidth was fb = 25 kHz due to a pulse shaping filter with roll...water. QPSK modulation was used with a symbol rate of 4 ksps. The carrier frequency was fc = 17 kHz. The structure of the transmission packet is

Context-Dependent Duration Signals in the Primate Prefrontal Cortex

PubMed Central

Genovesio, Aldo; Seitz, Lucia K.; Tsujimoto, Satoshi; Wise, Steven P.

2016-01-01

The activity of some prefrontal (PF) cortex neurons distinguishes short from long time intervals. Here, we examined whether this property reflected a general timing mechanism or one dependent on behavioral context. In one task, monkeys discriminated the relative duration of 2 stimuli; in the other, they discriminated the relative distance of 2 stimuli from a fixed reference point. Both tasks had a pre-cue period (interval 1) and a delay period (interval 2) with no discriminant stimulus. Interval 1 elapsed before the presentation of the first discriminant stimulus, and interval 2 began after that stimulus. Both intervals had durations of either 400 or 800 ms. Most PF neurons distinguished short from long durations in one task or interval, but not in the others. When neurons did signal something about duration for both intervals, they did so in an uncorrelated or weakly correlated manner. These results demonstrate a high degree of context dependency in PF time processing. The PF, therefore, does not appear to signal durations abstractedly, as would be expected of a general temporal encoder, but instead does so in a highly context-dependent manner, both within and between tasks. PMID:26209845

Association Between Hormones and Metabolic Syndrome in Older Italian Men

PubMed Central

Maggio, Marcello; Lauretani, Fulvio; Ceda, Gian Paolo; Bandinelli, Stefania; Basaria, Shehzad; Ble, Alessandro; Egan, Josephine; Paolisso, Giuseppe; Najjar, Samer; Metter, E. Jeffrey; Valenti, Giorgio; Guralnik, Jack M.; Ferrucci, Luigi

2009-01-01

OBJECTIVES To determine whether low levels of testosterone, sex hormone binding globulin (SHBG), insulin-like growth factor-1 (IGF-1), and dehydroepiandrosterone sulfate (DHEAS) and high levels of cortisol and leptin would be associated with metabolic syndrome (MS). DESIGN Cross-sectional. SETTING Population-based sample of older Italian men. PARTICIPANTS Four hundred fifty-two men aged 65 and older enrolled in the Invecchiare in Chianti (InCHIANTI) study. MEASUREMENTS Complete data on testosterone, cortisol, DHEAS, SHBG, fasting insulin, IGF-1 and leptin. MS was defined according to Adult Treatment Panel III criteria. RESULTS MS was present in 73 men (15.8% of the sample). After adjusting for confounders, total testosterone (P<.05) and log (SHBG) (P<.001) were inversely associated, whereas log (leptin) was positively associated with MS (P<.001). Independent of age, log (SHBG) was positively associated with high-density lipoprotein cholesterol (P<.05) and negatively associated with abdominal obesity (P<.001) and triglycerides (P<.001). Log (leptin) was significantly associated with each component of MS. Cortisol, DHEAS, free and bioavailable testosterone, and IGF-1 were not associated with MS. Having three or more hormones in the lower (for hormones lower in MS) or the upper (for hormones higher in MS) quartile was associated with three times the risk of being affected by MS (odds ratio =2.8, 95% confidence interval =1.3–6.9) (P=.005), compared with not having this condition. CONCLUSION Total testosterone and SHBG are negatively and leptin is positively associated with MS in older men. Whether specific patterns of hormonal dysregulation predict the development of MS should be tested in longitudinal studies. PMID:17198487

Single Doses up to 800 mg of E-52862 Do Not Prolong the QTc Interval – A Retrospective Validation by Pharmacokinetic-Pharmacodynamic Modelling of Electrocardiography Data Utilising the Effects of a Meal on QTc to Demonstrate ECG Assay Sensitivity

PubMed Central

Täubel, Jörg; Ferber, Georg; Lorch, Ulrike; Wang, Duolao; Sust, Mariano; Camm, A. John

2015-01-01

Background E-52862 is a Sigma-1 receptor antagonist (S1RA) currently under investigation as a potential analgesic medicine. We successfully applied a concentration-effect model retrospectively to a four-way crossover Phase I single ascending dose study and utilized the QTc shortening effects of a meal to demonstrate assay sensitivity by establishing the time course effects from baseline in all four periods, independently from any potential drug effects. Methods Thirty two healthy male and female subjects were included in four treatment periods to receive single ascending doses of 500 mg, 600 mg or 800 mg of E-52862 or placebo. PK was linear over the dose range investigated and doses up to 600 mg were well tolerated. The baseline electrocardiography (ECG) measurements on Day-1 were time-matched with ECG and pharmacokinetic (PK) samples on Day 1 (dosing day). Results In this conventional mean change to time-matched placebo analysis, the largest time-matched difference to placebo QTcI was 1.44 ms (90% CI: -4.04, 6.93 ms) for 500 mg; -0.39 ms (90% CI: -3.91, 3.13 ms) for 600 mg and 1.32 ms (90% CI: -1.89, 4.53 ms) for 800 mg of E-52862, thereby showing the absence of any QTc prolonging effect at the doses tested. In addition concentration-effect models, one based on the placebo corrected change from baseline and one for the change of QTcI from average baseline with time as fixed effect were fitted to the data confirming the results of the time course analysis. Conclusion The sensitivity of this study to detect small changes in the QTc interval was confirmed by demonstrating a shortening of QTcF of -8.1 (90% CI: -10.4, -5.9) one hour and -7.2 (90% CI: -9.4, -5.0) three hours after a standardised meal. Trial Registration EU Clinical Trials Register EudraCT 2010 020343 13 PMID:26291080

Resistance training intensity and volume affect changes in rate of force development in resistance-trained men.

PubMed

Mangine, Gerald T; Hoffman, Jay R; Wang, Ran; Gonzalez, Adam M; Townsend, Jeremy R; Wells, Adam J; Jajtner, Adam R; Beyer, Kyle S; Boone, Carleigh H; Miramonti, Amelia A; LaMonica, Michael B; Fukuda, David H; Ratamess, Nicholas A; Stout, Jeffrey R

2016-12-01

To compare the effects of two different resistance training programs, high intensity (INT) and high volume (VOL), on changes in isometric force (FRC), rate of force development (RFD), and barbell velocity during dynamic strength testing. Twenty-nine resistance-trained men were randomly assigned to either the INT (n = 15, 3-5 RM, 3-min rest interval) or VOL (n = 14, 10-12 RM, 1-min rest interval) training group for 8 weeks. All participants completed a 2-week preparatory phase prior to randomization. Measures of barbell velocity, FRC, and RFD were performed before (PRE) and following (POST) the 8-week training program. Barbell velocity was determined during one-repetition maximum (1RM) testing of the squat (SQ) and bench press (BP) exercises. The isometric mid-thigh pull was used to assess FRC and RFD at specific time bands ranging from 0 to 30, 50, 90, 100, 150, 200, and 250 ms. Analysis of covariance revealed significant (p < 0.05) group differences in peak FRC, FRC at 30-200 ms, and RFD at 50-90 ms. Significant (p < 0.05) changes in INT but not VOL in peak FRC (INT: 9.2 ± 13.8 %; VOL: -4.3 ± 10.2 %), FRC at 30-200 ms (INT: 12.5-15.8 %; VOL: -1.0 to -4.3 %), and RFD at 50 ms (INT: 78.0 ± 163 %; VOL: -4.1 ± 49.6 %) were observed. A trend (p = 0.052) was observed for RFD at 90 ms (INT: 58.5 ± 115 %; VOL: -3.5 ± 40.1 %). No group differences were observed for the observed changes in barbell velocity. Results indicate that INT is more advantageous than VOL for improving FRC and RFD, while changes in barbell velocity during dynamic strength testing are similarly improved by both protocols in resistance-trained men.

High intensity interval training for people with multiple sclerosis: A systematic review.

PubMed

Campbell, Evan; Coulter, Elaine H; Paul, Lorna

2018-06-13

Aerobic high intensity interval training (HIIT) is safe in the general population and more efficient in improving fitness than continuous moderate intensity training. The body of literature examining HIIT in multiple sclerosis (MS) is expanding but to date a systematic review has not been conducted. The aim of this review was to investigate the efficacy and safety of HIIT in people with MS. A systematic search was carried out in September 2017 in EMBASE, MEDline, PEDro, CENTRAL and Web of Science Core collections using appropriate keywords and MeSH descriptors. Reference lists of relevant articles were also searched. Articles were eligible for inclusion if they were published in English, used HIIT, and included participants with MS. Quality was assessed using the PEDro scale. The following data were extracted using a standardised form: study design and characteristics, outcome measures, significant results, drop-outs, and adverse events. Seven studies (described by 11 articles) were identified: four randomised controlled trials, one randomised cross-over trial and two cohort studies. PEDro scores ranged from 3 to 8. Included participants (n = 249) were predominantly mildly disabled; one study included only people with progressive MS. Six studies used cycle ergometry and one used arm ergometry to deliver HIIT. One study reported six adverse events, four which could be attributed to the intervention. The other six reported that there were no adverse events. Six studies reported improvements in at least one outcome measure, however there were 60 different outcome measures in the seven studies. The most commonly measured domain was fitness, which improved in five of the six studies measuring aspects of fitness. The only trial not to report positive results included people with progressive and a more severe level of disability (Extended Disability Status Scale 6.0-8.0). HIIT appears to be safe and effective in increasing fitness in people with MS and low levels of disability. Further research is required to explore the effectiveness of HIIT in people with progressive MS and in those with higher levels of disability. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Single Doses up to 800 mg of E-52862 Do Not Prolong the QTc Interval--A Retrospective Validation by Pharmacokinetic-Pharmacodynamic Modelling of Electrocardiography Data Utilising the Effects of a Meal on QTc to Demonstrate ECG Assay Sensitivity.

PubMed

Täubel, Jörg; Ferber, Georg; Lorch, Ulrike; Wang, Duolao; Sust, Mariano; Camm, A John

2015-01-01

E-52862 is a Sigma-1 receptor antagonist (S1RA) currently under investigation as a potential analgesic medicine. We successfully applied a concentration-effect model retrospectively to a four-way crossover Phase I single ascending dose study and utilized the QTc shortening effects of a meal to demonstrate assay sensitivity by establishing the time course effects from baseline in all four periods, independently from any potential drug effects. Thirty two healthy male and female subjects were included in four treatment periods to receive single ascending doses of 500 mg, 600 mg or 800 mg of E-52862 or placebo. PK was linear over the dose range investigated and doses up to 600 mg were well tolerated. The baseline electrocardiography (ECG) measurements on Day-1 were time-matched with ECG and pharmacokinetic (PK) samples on Day 1 (dosing day). In this conventional mean change to time-matched placebo analysis, the largest time-matched difference to placebo QTcI was 1.44 ms (90% CI: -4.04, 6.93 ms) for 500 mg; -0.39 ms (90% CI: -3.91, 3.13 ms) for 600 mg and 1.32 ms (90% CI: -1.89, 4.53 ms) for 800 mg of E-52862, thereby showing the absence of any QTc prolonging effect at the doses tested. In addition concentration-effect models, one based on the placebo corrected change from baseline and one for the change of QTcI from average baseline with time as fixed effect were fitted to the data confirming the results of the time course analysis. The sensitivity of this study to detect small changes in the QTc interval was confirmed by demonstrating a shortening of QTcF of -8.1 (90% CI: -10.4, -5.9) one hour and -7.2 (90% CI: -9.4, -5.0) three hours after a standardised meal. EU Clinical Trials Register EudraCT 2010 020343 13.

Evaluation of an imputed pitch velocity model of the auditory kappa effect.

PubMed

Henry, Molly J; McAuley, J Devin

2009-04-01

Three experiments evaluated an imputed pitch velocity model of the auditory kappa effect. Listeners heard 3-tone sequences and judged the timing of the middle (target) tone relative to the timing of the 1st and 3rd (bounding) tones. Experiment 1 held pitch constant but varied the time (T) interval between bounding tones (T = 728, 1,000, or 1,600 ms) in order to establish baseline performance levels for the 3 values of T. Experiments 2 and 3 combined the values of T tested in Experiment 1 with a pitch manipulation in order to create fast (8 semitones/728 ms), medium (8 semitones/1,000 ms), and slow (8 semitones/1,600 ms) velocity conditions. Consistent with an auditory motion hypothesis, distortions in perceived timing were larger for fast than for slow velocity conditions for both ascending sequences (Experiment 2) and descending sequences (Experiment 3). Overall, results supported the proposed imputed pitch velocity model of the auditory kappa effect. (c) 2009 APA, all rights reserved.

The association of long-term glycaemic variability versus sustained chronic hyperglycaemia with heart rate-corrected QT interval in patients with type 2 diabetes.

PubMed

Su, Jian-Bin; Yang, Xiao-Hua; Zhang, Xiu-Lin; Cai, Hong-Li; Huang, Hai-Yan; Zhao, Li-Hua; Xu, Feng; Chen, Tong; Cheng, Xing-Bo; Wang, Xue-Qin; Lu, Yan

2017-01-01

Prolonged heart rate-corrected QT(QTc) interval is related to ventricular arrhythmia and cardiovascular mortality, with considerably high prevalence of type 2 diabetes. Additionally, long-term glycaemic variability could be a significant risk factor for diabetic complications in addition to chronic hyperglycaemia. We compared the associations of long-term glycaemic variability versus sustained chronic hyperglycaemia with the QTc interval among type 2 diabetes patients. In this cross-sectional study, 2904 type 2 diabetes patients were recruited who had undergone at least four fasting plasma glucose (FPG) and 2-hour postprandial plasma glucose (PPG) measurements (at least once for every 3 months, respectively) during the preceding year. Long-term glycaemic variabilities of FPG and 2-hour PPG were assessed by their standard deviations (SD-FPG and SD-PPG, respectively), and chronic fasting and postprandial hyperglycaemia were assessed by their means (M-FPG and M-PPG, respectively). HbA1c was also determined upon enrolment to assess current overall glycaemic control. QTc interval was estimated from resting 12-lead electrocardiograms, and more than 440 ms was considered abnormally prolonged. Patients with prolonged QTc interval (≥440 ms) had greater M-FPG, M-PPG, SD-PPG and HbA1c than those with normal QTc interval but comparable SD-FPG. QTc interval was correlated with M-FPG, M-PPG, SD-PPG and HbA1c (r = 0.133, 0.153, 0.245 and 0.207, respectively, p = 0.000) but not with SD-FPG (r = 0.024, p = 0.189). After adjusting for metabolic risk factors via multiple linear regression analysis, SD-PPG, M-PPG and HbA1c (t = 12.16, 2.69 and 10.16, respectively, p = 0.000) were the major independent contributors to the increased QTc interval. The proportion of prolonged QTc interval increased significantly from 10.9% to 14.2% to 26.6% for the first (T1) to second (T2) to third (T3) tertiles of SD-PPG. After adjusting via multiple logistic regression analysis, the odd ratios of prolonged QTc interval of the T2 and T3 versus the T1 of SD-PPG were 1.15 (95% CI, 0.82-1.60) and 2.62 (1.92-3.57), respectively. Increased long-term variability of PPG is a strong independent risk factor for prolonged QTc interval in type 2 diabetes patients, in addition to long-term postprandial hyperglycaemia and current HbA1c.

The IRIDICA PCR/Electrospray Ionization-Mass Spectrometry Assay on Bronchoalveolar Lavage for Bacterial Etiology in Mechanically Ventilated Patients with Suspected Pneumonia.

PubMed

Strålin, Kristoffer; Ehn, Fredrik; Giske, Christian G; Ullberg, Måns; Hedlund, Jonas; Petersson, Johan; Spindler, Carl; Özenci, Volkan

2016-01-01

We studied the diagnostic performance of the IRIDICA PCR/electrospray ionization-mass spectrometry (PCR/ESI-MS) assay applied on bronchoalveolar lavage (BAL) samples, from 51 mechanically ventilated patients with suspected pneumonia, in a prospective study. In 32 patients with X-ray verified pneumonia, PCR/ESI-MS was positive in 66% and BAL culture was positive in 38% (p = 0.045), and either of the methods was positive in 69%. The following BAL result combinations were noted: PCR/ESI-MS+/culture+, 34%; PCR/ESI-MS+/culture-, 31%; PCR/ESI-MS-/culture+, 3.1%; PCR/ESI-MS-/culture-, 31%; kappa 0.36 (95% confidence interval (CI), 0.10-0.63). In pneumonia patients without prior antibiotic treatment, optimal agreement was noted with 88% PCR/ESI-MS+/culture+ and 12% PCR/ESI-MS-/culture- (kappa 1.0). However, in patients with prior antibiotic treatment, the test agreement was poor (kappa 0.16; 95% CI, -0.10-0.44), as 10 patients were PCR/ESI-MS+/culture-. In 8/10 patients the pathogens detected by PCR/ESI-MS could be detected by other conventional tests or PCR tests on BAL. Compared with BAL culture, PCR/ESI-MS showed specificities and negative predictive values of ≥87% for all individual pathogens, an overall sensitivity of 77% and positive predictive value (PPV) of 42%. When other conventional tests and PCR tests were added to the reference standard, the overall PPV increased to 87%. The PCR/ESI-MS semi-quantitative level tended to be higher for PCR/ESI-MS positive cases with pneumonia compared with cases without pneumonia (p = 0.074). In conclusion, PCR/ESI-MS applied on BAL showed a promising performance and has potential to be clinically useful in mechanically ventilated patients with suspected pneumonia. The usefulness of the method for establishment of pneumonia etiology and selection of antibiotic therapy should be further studied.

The steroid response to human chorionic gonadotropin (hCG) stimulation in men with Klinefelter syndrome does not change using immunoassay or mass spectrometry.

PubMed

Roli, L; Santi, D; Belli, S; Tagliavini, S; Cavalieri, S; De Santis, M C; Baraldi, E; Fanelli, F; Mezzullo, M; Granata, A R; Pagotto, U; Pasquali, R; Rochira, V; Carani, C; Simoni, M; Trenti, T

2017-08-01

Liquid-chromatography tandem mass-spectrometry (LC-MS/MS) was developed in parallel to Immunoassays (IAs) and today is proposed as the "gold standard" for steroid assays. Leydig cells of men with Klinefelter syndrome (KS) are able to respond to human chorionic gonadotropin (hCG) stimulation, even if testosterone (T) production was impaired. The aim was to evaluate how results obtained by IAs and LC-MS/MS can differently impact on the outcome of a clinical research on gonadal steroidogenesis after hCG stimulation. A longitudinal, prospective, case-control clinical trial. (clinicaltrial.gov NCT02788136) was carried out, enrolling KS men and healthy age-matched controls, stimulated by hCG administration. Serum steroids were evaluated at baseline and for 5 days after intramuscular injection of 5000 IU hCG using both IAs and LC-MS/MS. 13 KS patients (36 ± 9 years) not receiving T replacement therapy and 14 controls (32 ± 8 years) were enrolled. T, progesterone, cortisol, 17-hydroxy-progesterone (17OHP) and androstenedione, were significantly higher using IAs than LC-MS/MS. IAs and LC-MS/MS showed direct correlation for all five steroids, although the constant overestimation detected by IAs. Either methodology found the same 17OHP and T increasing profile after hCG stimulation, with equal areas under the curves (AUCs). Although a linearity between IA and LC-MS/MS is demonstrated, LC-MS/MS is more sensitive and accurate, whereas IA shows a constant overestimation of sex steroid levels. This result suggests the need of reference intervals built on the specific assay. This fundamental difference between these two methodologies opens a deep reconsideration of what is needed to improve the accuracy of steroid hormone assays.

The IRIDICA PCR/Electrospray Ionization–Mass Spectrometry Assay on Bronchoalveolar Lavage for Bacterial Etiology in Mechanically Ventilated Patients with Suspected Pneumonia

PubMed Central

Ehn, Fredrik; Giske, Christian G.; Ullberg, Måns; Hedlund, Jonas; Petersson, Johan; Spindler, Carl; Özenci, Volkan

2016-01-01

We studied the diagnostic performance of the IRIDICA PCR/electrospray ionization–mass spectrometry (PCR/ESI-MS) assay applied on bronchoalveolar lavage (BAL) samples, from 51 mechanically ventilated patients with suspected pneumonia, in a prospective study. In 32 patients with X-ray verified pneumonia, PCR/ESI-MS was positive in 66% and BAL culture was positive in 38% (p = 0.045), and either of the methods was positive in 69%. The following BAL result combinations were noted: PCR/ESI-MS+/culture+, 34%; PCR/ESI-MS+/culture-, 31%; PCR/ESI-MS-/culture+, 3.1%; PCR/ESI-MS-/culture-, 31%; kappa 0.36 (95% confidence interval (CI), 0.10–0.63). In pneumonia patients without prior antibiotic treatment, optimal agreement was noted with 88% PCR/ESI-MS+/culture+ and 12% PCR/ESI-MS-/culture- (kappa 1.0). However, in patients with prior antibiotic treatment, the test agreement was poor (kappa 0.16; 95% CI, -0.10–0.44), as 10 patients were PCR/ESI-MS+/culture-. In 8/10 patients the pathogens detected by PCR/ESI-MS could be detected by other conventional tests or PCR tests on BAL. Compared with BAL culture, PCR/ESI-MS showed specificities and negative predictive values of ≥87% for all individual pathogens, an overall sensitivity of 77% and positive predictive value (PPV) of 42%. When other conventional tests and PCR tests were added to the reference standard, the overall PPV increased to 87%. The PCR/ESI-MS semi-quantitative level tended to be higher for PCR/ESI-MS positive cases with pneumonia compared with cases without pneumonia (p = 0.074). In conclusion, PCR/ESI-MS applied on BAL showed a promising performance and has potential to be clinically useful in mechanically ventilated patients with suspected pneumonia. The usefulness of the method for establishment of pneumonia etiology and selection of antibiotic therapy should be further studied. PMID:27463099

Estimation of TOA based MUSIC algorithm and cross correlation algorithm of appropriate interval

NASA Astrophysics Data System (ADS)

Lin, Wei; Liu, Jun; Zhou, Yineng; Huang, Jiyan

2017-03-01

Localization of mobile station (MS) has now gained considerable attention due to its wide applications in military, environmental, health and commercial systems. Phrase angle and encode data of MSK system model are two critical parameters in time-of-arrival (TOA) localization technique; nevertheless, precise value of phrase angle and encode data are not easy to achieved in general. In order to meet the actual situation, we should consider the condition that phase angle and encode data is unknown. In this paper, a novel TOA localization method, which combine MUSIC algorithm and cross correlation algorithm in an appropriate interval, is proposed. Simulations show that the proposed method has better performance than music algorithm and cross correlation algorithm of the whole interval.

Negative Mood State Enhances the Susceptibility to Unpleasant Events: Neural Correlates from a Music-Primed Emotion Classification Task

PubMed Central

Yuan, Jiajin; Chen, Jie; Yang, Jiemin; Ju, Enxia; Norman, Greg J.; Ding, Nanxiang

2014-01-01

Background Various affective disorders are linked with enhanced processing of unpleasant stimuli. However, this link is likely a result of the dominant negative mood derived from the disorder, rather than a result of the disorder itself. Additionally, little is currently known about the influence of mood on the susceptibility to emotional events in healthy populations. Method Event-Related Potentials (ERP) were recorded for pleasant, neutral and unpleasant pictures while subjects performed an emotional/neutral picture classification task during positive, neutral, or negative mood induced by instrumental Chinese music. Results Late Positive Potential (LPP) amplitudes were positively related to the affective arousal of pictures. The emotional responding to unpleasant pictures, indicated by the unpleasant-neutral differences in LPPs, was enhanced during negative compared to neutral and positive moods in the entire LPP time window (600–1000 ms). The magnitude of this enhancement was larger with increasing self-reported negative mood. In contrast, this responding was reduced during positive compared to neutral mood in the 800–1000 ms interval. Additionally, LPP reactions to pleasant stimuli were similar across positive, neutral and negative moods except those in the 800–900 ms interval. Implications Negative mood intensifies the humans' susceptibility to unpleasant events in healthy individuals. In contrast, music-induced happy mood is effective in reducing the susceptibility to these events. Practical implications of these findings were discussed. PMID:24587070

A comparative dose-effect study with cardiac glycosides assessing cardiac and extracardiac responses in normal subjects.

PubMed

Alken, R G; Belz, G G

1984-01-01

We tested the hypothesis that differences exist in the pharmacodynamic pattern of different cardiac glycosides. We conducted a randomized, placebo-controlled study in normal volunteers and evaluated the effects of weekly increased oral dosing of digoxin (n = 10; from 0.25 to 1.0 mg/day), meproscillarin (n = 10; from 0.5 to 2.0 mg/day), and placebo (n = 5). To determine the glycoside effects, corrected electromechanical systole (QS2c) was used to measure inotropy and the PQ interval to test dromotropy. Red-green discrimination and critical flicker fusion (CFF) assessed visual functions. Subjective complaints were collected using rating lists. Both glycosides dose dependently shortened QS2c and prolonged PQ interval. PQ prolongations over +20 ms occurred in seven of 10 digoxin subjects, in two of 10 meproscillarin, and in one of five placebo. Equi-inotropic response, identified at 12 ms mean QS2c shortening, revealed the relative potency of digoxin to be 2.4 times higher than meproscillarin; this ratio increased to sevenfold for equi-effective negative dromotropic effects at 12 ms mean PQ prolongation. Each drug was associated with a dominant subjective complaint: digoxin with anergy and meproscillarin with diarrhea. Red-green discrimination was better under meproscillarin and CFF was depressed by digoxin. The results indicate that pharmacodynamic differences exist between cardiac glycosides. A differential use of various glycosides should be considered and tested clinically.

Interactions between rewarding lateral hypothalamic and aversive nucleus reticularis gigantocellularis stimulation.

PubMed

Diotte, M; Miguelez, M; Miliaressis, E; Bielajew, C

2000-12-05

The interaction between rewarding and aversive consequences of brain stimulation were assessed in two studies. In the first, the frequency threshold for 300 ms trains of combined lateral hypothalamic (LH) and nucleus reticularis gigantocellularis (Gi) stimulation, in which each LH pulse was followed 2 ms later by the Gi one, was determined for one month. Compared to the threshold for trains of single LH pulses, combined LH-Gi stimulation initially increased the frequency threshold; however, this effect reversed within one session and was subsequently maintained for the duration of the study. The aversion produced by Gi stimulation, as measured by latency to escape, was abolished following a single session of LH-Gi pairs. In the second study, a subset of animals received both presentations of combined pulses, LH followed by Gi, and the reverse; the interval between pulses was varied from 0.2 to 6.4 ms. The effectiveness of combined stimulation, determined by the ratio of LH frequency thresholds to that of the LH-Gi ranged from 0 to 50% across animals but the individual effectiveness functions within animals did not vary with different intervals. In addition, the order of presentation of pulses was of no consequence. Thus, not only did exposure to LH stimulation appear to obliterate Gi aversion, but the combination of LH and Gi pulses added to the rewarding effect produced by LH stimulation alone.

General Mathematical Ability Predicts PASAT Performance in MS Patients: Implications for Clinical Interpretation and Cognitive Reserve.

PubMed

Sandry, Joshua; Paxton, Jessica; Sumowski, James F

2016-03-01

The Paced Auditory Serial Addition Test (PASAT) is used to assess cognitive status in multiple sclerosis (MS). Although the mathematical demands of the PASAT seem minor (single-digit arithmetic), cognitive psychology research links greater mathematical ability (e.g., algebra, calculus) to more rapid retrieval of single-digit math facts (e.g., 5+6=11). The present study evaluated the hypotheses that (a) mathematical ability is related to PASAT performance and (b) both the relationship between intelligence and PASAT performance as well as the relationship between education and PASAT performance are both mediated by mathematical ability. Forty-five MS patients were assessed using the Wechsler Test of Adult Reading, PASAT and Calculation Subtest of the Woodcock-Johnson-III. Regression based path analysis and bootstrapping were used to compute 95% confidence intervals and test for mediation. Mathematical ability (a) was related to PASAT (β=.61; p<.001) and (b) fully mediated the relationship between Intelligence and PASAT (β=.76; 95% confidence interval (CI95)=.28, 1.45; direct effect of Intelligence, β=.42; CI95=-.39, 1.23) as well as the relationship between Education and PASAT (β=2.43, CI95=.81, 5.16, direct effect of Education, β=.83, CI95=-1.95, 3.61). Mathematical ability represents a source of error in the clinical interpretation of cognitive decline using the PASAT. Domain-specific cognitive reserve is discussed.

The molecular mechanism of the termination of insect diapause, part 1: A timer protein, TIME-EA4, in the diapause eggs of the silkworm Bombyx mori is a metallo-glycoprotein.

PubMed

Isobe, Minoru; Kai, Hidenori; Kurahashi, Takuya; Suwan, Sathorn; Pitchayawasin-Thapphasaraphong, Suthasinee; Franz, Thomas; Tani, Naoki; Higashi, Kenichiro; Nishida, Hideo

2006-10-01

TIME-EA4 is an ATPase that measures time intervals, functioning as a diapause duration clock in diapause eggs of the silkworm, Bombyx mori. Characterization of the primary and higher structures of the TIME-EA4 would be desirable to clarify the mechanism by which the protein measures the time intervals. In our current studies, the whole sequence of TIME-EA4 has been established as that of a metallo-glycoprotein by combinational means involving peptide sequence analysis, nano-HPLC-ESI-Q-TOF-MS and MS/MS, and cDNA dictation. The amino acid sequence of TIME-EA4 showed 46-55 % homology with the reported proteins of the Cu,Zn-SOD (superoxide dismutase) family; in particular, the SOD active site (core domain) includes metal-binding amino acid ligands and a disulfide bond, and these structures are completely identical in Bombyx SOD, bovine SOD, and TIME-EA4 proteins. We found, however, that TIME-EA4 contains one more copper ion than other SODs, as was proven under neutral nondenaturing conditions. ESI mass spectrometry revealed that the timer function was not in the SOD core domain. In addition, TIME-EA4 has an attached sugar chain, which is indispensable to its functioning as a timer protein.

Association between dietary patterns and metabolic syndrome in Chinese adults: a propensity score-matched case-control study.

PubMed

Xia, Yang; Gu, Yeqing; Yu, Fei; Zhang, Qing; Liu, Li; Meng, Ge; Wu, Hongmei; Du, Huanmin; Shi, Hongbin; Guo, Xiaoyan; Liu, Xing; Li, Chunlei; Han, Peipei; Dong, Renwei; Wang, Xiuyang; Bao, Xue; Su, Qian; Fang, Liyun; Liu, Fangfang; Yang, Huijun; Kang, Li; Ma, Yixuan; Yu, Bin; Sun, Shaomei; Wang, Xing; Zhou, Ming; Jia, Qiyu; Guo, Qi; Wu, Yuntang; Song, Kun; Huang, Guowei; Wang, Guolin; Niu, Kaijun

2016-10-06

Previous studies indicated that dietary patterns were associated with metabolic syndrome (MS), but little is known in Chinese. We design this case-control study to evaluate the associations between dietary patterns and MS in Chinese adults. In this study, 1492 participants with MS were matched with 1492 controls using the 1:1 ratio propensity score matching methods. Dietary intake was assessed using a valid self-administered food frequency questionnaire, and MS was defined in accordance with the criteria of the American Heart Association scientific statement of 2009. Higher scores for the high-protein/cholesterol pattern were associated with higher prevalence of MS. Compared with the participants in the lowest quartile, the odds ratio (OR) for the extreme quartile was 1.36 (95% confidence interval (CI), 1.10-1.68) and the P for trend <0.01 after adjusted for the other two dietary pattern scores. We also found a moderate consumption of the balanced pattern was associated with the lowest prevalence of MS. The ORs across quartiles of the balanced pattern were 1 (reference), 0.83 (95% CI, 0.68-1.02), 0.69 (95% CI, 0.56-0.85), and 0.84 (95% CI, 0.68-1.04) after adjustment. Our study demonstrates that there is a strong association between a diet rich in animal offal, animal blood, meat, and sausage and a higher prevalence of MS.

Employment, disability pension and income for children with parental multiple sclerosis.

PubMed

Moberg, Julie Yoon; Laursen, Bjarne; Koch-Henriksen, Nils; Thygesen, Lau Caspar; Brødsgaard, Anne; Soelberg Sørensen, Per; Magyari, Melinda

2017-07-01

Little is known about the consequences of parental multiple sclerosis (MS) on offspring's socioeconomic circumstances. To investigate employment, disability pension and income in offspring of parents with MS compared with matched reference persons in a nationwide register-based cohort study. All Danish-born persons with onset of MS during 1950-1986 were retrieved from the Danish Multiple Sclerosis Registry. Their offspring were identified using the Civil Registration System. One random offspring from each sibship was matched by sex and year of birth with eight random reference persons. We included 2456 MS offspring and 19,648 reference persons. At age 30, employment was lower among MS offspring than reference children (odds ratio (OR): 0.89; 95% confidence interval (CI): 0.84-0.95; p = 0.0003), and they more often received disability pension (OR: 1.31; 95% CI: 1.15-1.50; p < 0.0001) at ages 30 and 40 but not at age 50. Although the mean income was not significantly lower for the MS offspring cohort, most of them attained an annual personal income below 250,000 DKK (Danish krone), that is, ~33,650 EUR (OR: 0.91; 95% CI: 0.84-0.99; p = 0.04). Having had a parent with MS may affect employment and increase the risk of disability pension and low income in adult life.

Increased plasma/serum levels of prolactin in multiple sclerosis: a meta-analysis.

PubMed

Wei, Wei; Liu, Lei; Cheng, Zhong-Le; Hu, Bo

2017-08-01

Prolactin (PRL) is a polypeptide hormone that is known to stimulate humoral and cell mediated immune responses. PRL levels have been investigated in several autoimmune diseases including multiple sclerosis (MS); however, these have yielded different and inconsistent results. This study aims to perform a more precise evaluation on the plasma/serum PRL levels in MS patients, and to explore the available influential factors. Research related to plasma/serum PRL levels in MS patients and healthy controls were gathered using PubMed, EMBASE and The Cochrane Library database (until Mar 31 2016). Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by fixed-effects or random-effect model analysis. Heterogeneity test was performed by the Q statistic and quantified using I 2 , and publication bias was evaluated using a funnel plot and Egger's linear regression test. 516 articles were obtained after searching databases, and 8 studies with 426 MS patients and 296 controls were finally included. Meta-analysis revealed that, compared with the control group, the MS group had significantly higher plasma/serum PRL levels, with the SMD of 0.55 and 95%CI (0.39, 0.72). Subgroup analyses showed that region, age and disease duration were associated with PRL level in MS patients. In summary, our meta-analysis revealed a significantly higher PRL level in MS patients than healthy controls, and it is influenced by region, age and disease duration.

Magnetic resonance imaging as a surrogate outcome for multiple sclerosis relapses

PubMed Central

Petkau, J; Reingold, SC; Held, U; Cutter, GR; Fleming, TR; Hughes, MD; Miller, DH; McFarland, HF; Wolinsky, JS

2009-01-01

Background Magnetic resonance imaging (MRI) of lesions in the brain may be the best current candidate for a surrogate biological marker of clinical outcomes in relapsing remitting multiple sclerosis (MS), based on its role as an objective indicator of disease pathology. No biological surrogate marker has yet been validated for MS clinical outcomes. Objective The objective of this study was to use a multi-phased study to determine if a valid surrogate relationship could be demonstrated between counts of contrast enhancing lesions (CELs) and occurrence of relapses in MS. Methods We examined correlations for the concurrent and predictive relationship between CELs over 6 months and MS relapses over the same 6 months and an additional 6 months (total: 12 months), using available data on untreated patients from a large clinical trial and natural history database. Results Concurrent and predictive correlations were inadequate to justify continuation of this study to the planned additional phases required to demonstrate a surrogate relationship between CELs and MS relapses. Conclusions Confidence intervals for correlations between CELs and MS relapses exclude the possibility that CELs can be a good surrogate for relapses over the time scales we investigated. Further exploration of surrogacy between MRI measures and MS clinical outcomes may require improved datasets, the development of MRI techniques that couple better to clinical disease, and the ability to test a wide range of imaging- and clinically-based hypotheses for surrogacy. PMID:18535021

Geographical Heterogeneity of Multiple Sclerosis Prevalence in France.

PubMed

Pivot, Diane; Debouverie, Marc; Grzebyk, Michel; Brassat, David; Clanet, Michel; Clavelou, Pierre; Confavreux, Christian; Edan, Gilles; Leray, Emmanuelle; Moreau, Thibault; Vukusic, Sandra; Hédelin, Guy; Guillemin, Francis

2016-01-01

Geographical variation in the prevalence of multiple sclerosis (MS) is controversial. Heterogeneity is important to acknowledge to adapt the provision of care within the healthcare system. We aimed to investigate differences in prevalence of MS in departments in the French territory. We estimated MS prevalence on October 31, 2004 in 21 administrative departments in France (22% of the metropolitan departments) by using multiple data sources: the main French health insurance systems, neurologist networks devoted to MS and the Technical Information Agency of Hospitalization. We used a spatial Bayesian approach based on estimating the number of MS cases from 2005 and 2008 capture-recapture studies to analyze differences in prevalence. The age- and sex-standardized prevalence of MS per 100,000 inhabitants ranged from 68.1 (95% credible interval 54.6, 84.4) in Hautes-Pyrénées (southwest France) to 296.5 (258.8, 338.9) in Moselle (northeast France). The greatest prevalence was in the northeast departments, and the other departments showed great variability. By combining multiple data sources into a spatial Bayesian model, we found heterogeneity in MS prevalence among the 21 departments of France, some with higher prevalence than anticipated from previous publications. No clear explanation related to health insurance coverage and hospital facilities can be advanced. Population migration, socioeconomic status of the population studied and environmental effects are suspected.

Recolonization of mutans Streptococci after application of chlorhexidine gel.

PubMed

Vale, Glauber Campos; Cury, Altair Antoninha Del Bel; Arthur, Rodrigo Alex; Cury, Jaime Aparecido; Tabchoury, Cínthia Pereira Machado

2014-01-01

Streptococcus mutans is specifically suppressed by intensive treatment with chlorhexidine gel, but the time for recolonization and the effect on other oral bacteria are not totally clear. In this study, recolonization of mutans streptococci was evaluated in nine healthy adult volunteers, who were highly colonized with this microorganism. Stimulated saliva was collected before (baseline) and at 1, 7, 14, 21 and 28 days after application of 1% chlorhexidine gel on volunteers' teeth for two consecutive days. On each day, the gel was applied using disposable trays for 3 x 5 min with intervals of 5 min between each application. Saliva was plated on blood agar to determine total microorganisms (TM); on mitis salivarius agar to determine total streptococci (TS) and on mitis salivarius agar plus bacitracin to determine mutans streptococci (MS). Chlorhexidine was capable of reducing the counts of MS and the proportion of MS with regard to total microorganisms (%MS/TM) (p<0.05), but these values did not differ statistically from baseline (p>0.05) after 14 days for MS and 21 days for %MS/TM. The counts of TM and TS and the proportion of MS to total streptococci did not differ statistically from baseline (p>0.05) after chlorhexidine treatment. The results suggest that the effect of chlorhexidine gel treatment on suppression of mutans streptococci is limited to less than a month in highly colonized individuals.

Effects of particulate matter exposure on multiple sclerosis hospital admission in Lombardy region, Italy

PubMed Central

Laura, Angelici; Mirko, Piola; Tommaso, Cavalleri; Giorgia, Randi; Francesca, Cortini; Roberto, Bergamaschi; Andrea, Baccarelli A; Alberto, Bertazzi Pier; Cecilia, Pesatori Angela; Valentina, Bollati

2016-01-01

Background Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the central nervous system, characterized by recurrent relapses of inflammation that cause mild to severe disability. Exposure to airborne particulate matter (PM) has been associated with acute increases in systemic inflammatory responses and neuroinflammation. In the present study, we hypothesize that exposure to PM < 10 µm in diameter (PM10) might increase the occurrence of MS-related hospitalizations. Methods We obtained daily concentrations of PM10 from 53 monitoring sites covering the study area and we identified 8287 MS-related hospitalization through hospital admission-discharge records of the Lombardy region, Italy, between 2001 and 2009. We used a Poisson regression analysis to investigate the association between exposure to PM10 and risk of hospitalization. Results A higher RR of hospital admission for MS relapse was associated with exposure to PM10 at different time intervals. The maximum effect of PM10 on MS hospitalization was found for exposure between days 0 and 7: Hospital admission for MS increased 42% (95%CI 1.39–1.45) on the days preceded by one week with PM10 levels in the highest quartile. The p-value for trend across quartiles was < 0.001. Conclusions These data support the hypothesis that air pollution may have a role in determining MS occurrence and relapses. Our findings could open new avenues for determining the pathogenic mechanisms of MS and potentially be applied to other autoimmune diseases. PMID:26624240

[Prevalence of metabolic syndrome in Mapuche individuals living in urban and rural environment in Chile].

PubMed

Ibáñez, Luis; Sanzana, Ruth; Salas, Carlos; Navarrete, Claudia; Cartes-Velásquez, Ricardo; Rainqueo, Angélica; Jara, Tamara; Pérez-Bravo, Francisco; Ulloa, Natalia; Calvo, Carlos; Miquel, Juan F; Celis-Morales, Carlos

2014-08-01

Metabolic Syndrome (MS) increases the risk of diabetes and mortality associated with cardiovascular disease. However, the prevalence of MS could differ by ethnicity and lifestyle factors. To determine the prevalence of MS in Mapuche individuals living in urban and rural environments in Chile and to investigate whether the prevalence and risk of MS in urban and rural environments differs by sex, age and nutritional status. A total of 1077 Mapuche participants were recruited from urban (MU = 288) and rural (MR = 789) settings. Body mass index, waist circumference and blood pressure were measured. A fasting blood sample was obtained to measure serum glucose, HDL cholesterol and triacylglycerol. The prevalence of MS was determined using the unified IDF and ATP-III criteria. An environment and sex interaction was found for the prevalence of MS (p = 0.042). The prevalence was significantly lower in male MR (13%) compared to other groups (22, 23 and 25% among female MR, female MU and male MU respectively). Also, the prevalence of central obesity and low HDL-cholesterol were significantly lower in male MR. MU are at an increased risk of developing MS compared to MR, with an odds ratio of 1.59 (95% confidence intervals 1.1 to 2.2). This risk increases along with age or body mass index of the population. The adoption of an urbanized lifestyle increases the risk of developing MS in Mapuche individuals. This risk is enhanced by age and nutritional status.

Motion sickness increases the risk of accidental hypothermia.

PubMed

Nobel, Gerard; Eiken, Ola; Tribukait, Arne; Kölegård, Roger; Mekjavic, Igor B

2006-09-01

Motion sickness (MS) has been found to increase body-core cooling during immersion in 28 degrees C water, an effect ascribed to attenuation of the cold-induced peripheral vasoconstriction (Mekjavic et al. in J Physiol 535(2):619-623, 2001). The present study tested the hypothesis that a more profound cold stimulus would override the MS effect on peripheral vasoconstriction and hence on the core cooling rate. Eleven healthy subjects underwent two separate head-out immersions in 15 degrees C water. In the control trial (CN), subjects were immersed after baseline measurements. In the MS-trial, subjects were rendered motion sick prior to immersion, by using a rotating chair in combination with a regimen of standardized head movements. During immersion in the MS-trial, subjects were exposed to an optokinetic stimulus (rotating drum). At 5-min intervals subjects rated their temperature perception, thermal comfort and MS discomfort. During immersion mean skin temperature, rectal temperature, the difference in temperature between the non-immersed right forearm and 3rd finger of the right hand (DeltaTff), oxygen uptake and heart rate were recorded. In the MS-trial, rectal temperature decreased substantially faster (33%, P < 0.01). Also, the DeltaTff response, an index of peripheral vasomotor tone, as well as the oxygen uptake, indicative of the shivering response, were significantly attenuated (P < 0.01 and P < 0.001, respectively) by MS. Thus, MS may predispose individuals to hypothermia by enhancing heat loss and attenuating heat production. This might have significant implications for survival in maritime accidents.

Association of infectious mononucleosis with multiple sclerosis. A population-based study.

PubMed

Ramagopalan, Sreeram V; Valdar, William; Dyment, David A; DeLuca, Gabriele C; Yee, Irene M; Giovannoni, Gavin; Ebers, George C; Sadovnick, A Dessa

2009-01-01

Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. Several studies have attempted to correlate exposure to viral illness with the subsequent development of MS. Here in a population-based Canadian cohort, we investigate the relationship between prior clinical infection or vaccination and the risk of MS. Using the longitudinal Canadian database, 14,362 MS index cases and 7,671 spouse controls were asked about history of measles, mumps, rubella, varicella and infectious mononucleosis as well as details about vaccination with measles, mumps, rubella, hepatitis B and influenza vaccines. Comparisons were made between cases and spouse controls. Spouse controls and stratification by sex appear to correct for ascertainment bias because with a single exception we found no significant differences between cases and controls for all viral exposures and vaccinations. However, 699 cases and 165 controls reported a history of infectious mononucleosis (p < 0.001, corrected odds ratio 2.06, 95% confidence interval 1.71-2.48). Females were more aware of disease history than males (p < 0.001). The data further confirms a reporting distortion between males and females. Historically reported measles, mumps, rubella, varicella and vaccination for hepatitis B, influenza, measles, mumps and rubella are not associated with increased risk of MS later in life. A clinical history of infectious mononucleosis is conspicuously associated with increased MS susceptibility. These findings support studies implicating Epstein-Barr virus in MS disease susceptibility, but a co-association between MS susceptibility and clinically apparent infectious mononucleosis cannot be excluded.

[Determination of the anaerobic threshold by the rate of ventilation and cardio interval variability].

PubMed

Seluianov, V N; Kalinin, E M; Pak, G D; Maevskaia, V I; Konrad, A H

2011-01-01

The aim of this work is to develop methods for determining the anaerobic threshold according to the rate of ventilation and cardio interval variability during the test with stepwise increases load on the cycle ergometer and treadmill. In the first phase developed the method for determining the anaerobic threshold for lung ventilation. 49 highly skilled skiers took part in the experiment. They performed a treadmill ski-walking test with sticks with gradually increasing slope from 0 to 25 degrees, the slope increased by one degree every minute. In the second phase we developed a method for determining the anaerobic threshold according dynamics ofcardio interval variability during the test. The study included 86 athletes of different sports specialties who performed pedaling on the cycle ergometer "Monarch" in advance. Initial output was 25 W, power increased by 25 W every 2 min. The pace was steady--75 rev/min. Measurement of pulmonary ventilation and oxygen and carbon dioxide content was performed using gas analyzer COSMED K4. Sampling of arterial blood was carried from the ear lobe or finger, blood lactate concentration was determined using an "Akusport" instrument. RR-intervals registration was performed using heart rate monitor Polar s810i. As a result, it was shown that the graphical method for determining the onset of anaerobic threshold ventilation (VAnP) coincides with the accumulation of blood lactate 3.8 +/- 0.1 mmol/l when testing on a treadmill and 4.1 +/- 0.6 mmol/1 on the cycle ergometer. The connection between the measure of oxygen consumption at VAnP and the dispersion of cardio intervals (SD1), derived regression equation: VO2AnT = 0.35 + 0.01SD1W + 0.0016SD1HR + + 0.106SD1(ms), l/min; (R = 0.98, error evaluation function 0.26 L/min, p < 0.001), where W (W)--Power, HR--heart rate (beats/min), SD1--cardio intervals dispersion (ms) at the moment of registration of cardio interval threshold.

Analyzing Thorough QT Study 1 & 2 in the Telemetric and Holter ECG Warehouse (THEW) using Hannover ECG System HES : A validation study.

PubMed

Khawaja, A; Petrovic, R; Safer, A; Baas, T; Dössel, O; Fischer, R

2010-01-01

Following the ICH E14 clinical evaluation guideline [1], the measurement of QT/QTc interval prolongation has become the standard surrogate biomarker for cardiac drug safety assessment and the faith of a drug development. In Thorough QT (TQT) study, a so-called positive control is employed to assess the ability of this study to detect the endpoint of interest, i.e. the QT prolongation by about five milliseconds. In other words the lower bound of the one-sided 95% confidence interval (CI) must be above 0 [ms]. Fully automated detection of ECG fiducial points and measurement of the corresponding intervals including QT intervals and RR intervals vary between different computerized algorithms. In this work we demonstrate the ability and reliability of Hannover ECG System (HES(®)) to assess drug effects by detecting QT/QTc prolongation effects that meet the threshold of regulatory concern as mentioned by using THEW database studies namely TQT studies one and two.

Dietary Inflammatory Index and risk of multiple sclerosis in a case-control study from Iran

PubMed Central

Shivappa, Nitin; Hébert, James R.; Behrooz, Maryam; Rashidkhani, Bahram

2016-01-01

Background Diet and inflammation have been suggested to be important risk factors for multiple sclerosis (MS). Objectives In this study, we examined the ability of the dietary inflammatory index (DII) to predict MS in a case-control study conducted in Iran. Methods This study included 68 MS cases and 140 controls hospitalized for acute non-neoplastic diseases. The DII was computed based on dietary intake assessed by a previously validated food frequency questionnaire. Logistic regression models were used to estimate odds ratios (ORs) adjusted for age, energy, sex, BMI, season of birth, rubella history, history of routine exercise before MS, smoking and history of consumption of cow's mile in the first 2 years of life. Results Subjects with higher DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of MS, with the DII being used as both a continuous variable (ORcontinuous 1.66, 95% confidence interval, (CI), 1.19-2.31; one unit increase corresponding to ≈15% of its range in the current study) and a categorical variable (ORdii>1.43 vs ≤ 1.43 2.68, 95%CI 1.15-6.26). Conclusions These results indicate that a pro-inflammatory diet is associated with increased risk of MS. PMID:27362443

Recovery function of the human brain stem auditory-evoked potential.

PubMed

Kevanishvili, Z; Lagidze, Z

1979-01-01

Amplitude reduction and peak latency prolongation were observed in the human brain stem auditory-evoked potential (BEP) with preceding (conditioning) stimulation. At a conditioning interval (CI) of 5 ms the alteration of BEP was greater than at a CI of 10 ms. At a CI of 10 ms the amplitudes of some BEP components (e.g. waves I and II) were more decreased than those of others (e.g. wave V), while the peak latency prolongation did not show any obvious component selectivity. At a CI of 5 ms, the extent of the amplitude decrement of individual BEP components differed less, while the increase in the peak latencies of the later components was greater than that of the earlier components. The alterations of the parameters of the test BEPs at both CIs are ascribed to the desynchronization of intrinsic neural events. The differential amplitude reduction at a CI of 10 ms is explained by the different durations of neural firings determining various effects of desynchronization upon the amplitudes of individual BEP components. The decrease in the extent of the component selectivity and the preferential increase in the peak latencies of the later BEP components observed at a CI of 5 ms are explained by the intensification of the mechanism of the relative refractory period.

Level of education and multiple sclerosis risk over a 50-year period: Registry-based sibling study.

PubMed

Bjørnevik, Kjetil; Riise, Trond; Benjaminsen, Espen; Celius, Elisabeth G; Dahl, Ole P; Kampman, Margitta T; Løken-Amsrud, Kristin I; Midgard, Rune; Myhr, Kjell-Morten; Torkildsen, Øivind; Vatne, Anita; Grytten, Nina

2017-02-01

The conflicting results from studies on socioeconomic status (SES) and multiple sclerosis (MS) risk might be due to a change in the distribution of environmental exposures over time or to methodological limitations in previous research. To examine the association between SES and MS risk during 50 years. We included patients registered in Norwegian MS registries and prevalence studies born between 1930 and 1979, and identified their siblings and parents using the Norwegian Population Registry. Information on education was retrieved from the National Education Registry, categorized into four levels (primary, secondary, undergraduate and graduate) and compared in patients and siblings using conditional logistic regression. A total of 4494 MS patients and 9193 of their siblings were included in the analyses. Level of education was inversely associated with MS risk ( p trend < 0.001) with an odds ratio (OR) of 0.73 (95% confidence interval (CI): 0.59-0.90) when comparing the highest and lowest levels. The effect estimates did not vary markedly between participants born before or after the median year of birth (1958), but we observed a significant effect modification by parental education ( p = 0.047). Level of education was inversely associated with MS risk, and the estimates were similar in the earliest and latest birth cohorts.

Investigation of modulation parameters in multiplexing gas chromatography.

PubMed

Trapp, Oliver

2010-10-22

Combination of information technology and separation sciences opens a new avenue to achieve high sample throughputs and therefore is of great interest to bypass bottlenecks in catalyst screening of parallelized reactors or using multitier well plates in reaction optimization. Multiplexing gas chromatography utilizes pseudo-random injection sequences derived from Hadamard matrices to perform rapid sample injections which gives a convoluted chromatogram containing the information of a single sample or of several samples with similar analyte composition. The conventional chromatogram is obtained by application of the Hadamard transform using the known injection sequence or in case of several samples an averaged transformed chromatogram is obtained which can be used in a Gauss-Jordan deconvolution procedure to obtain all single chromatograms of the individual samples. The performance of such a system depends on the modulation precision and on the parameters, e.g. the sequence length and modulation interval. Here we demonstrate the effects of the sequence length and modulation interval on the deconvoluted chromatogram, peak shapes and peak integration for sequences between 9-bit (511 elements) and 13-bit (8191 elements) and modulation intervals Δt between 5 s and 500 ms using a mixture of five components. It could be demonstrated that even for high-speed modulation at time intervals of 500 ms the chromatographic information is very well preserved and that the separation efficiency can be improved by very narrow sample injections. Furthermore this study shows that the relative peak areas in multiplexed chromatograms do not deviate from conventionally recorded chromatograms. Copyright © 2010 Elsevier B.V. All rights reserved.

CYP2C19 variation, not citalopram dose nor serum level, is associated with QTc prolongation.

PubMed

Kumar, Yingying; Kung, Simon; Shinozaki, Gen

2014-12-01

Recently, a FDA Safety Communication warned of a dose-dependent risk for QTc prolongation with citalopram, which is metabolized by CYP2C19 of the cytochrome P450 system. We investigate associations between citalopram and escitalopram dose, serum concentration, CYP2C19 phenotype, and QTc. We undertook a retrospective chart review of citalopram or escitalopram patients with the inclusion criteria of consistent medication dose, CYP2C19 phenotype (extensive metabolizers [EM], intermediate metabolizers [IM], poor metabolizers [PM]), and QTc interval on ECG. We further identified 42 citalopram users with citalopram serum concentration measurements and ECG. Regression and one-way ANOVA were used to examine the relationship between citalopram dose, citalopram serum concentration, CYP2C19 phenotype, and QTc interval. Of 75 citalopram patients, the EM group had significantly shorter QTc intervals than a combined IM+PM group (427.1±23.6 ms vs. 440.1±26.6 ms, one-tailed t-test, p=0.029). In the 80 escitalopram cohort, there was no significant difference in QTc between phenotype groups. There was no statistical correlation between citalopram (p=0.62) or escitalopram (p=0.30) dose and QTc. QTc was not associated with citalopram serum level (p=0.45). In contrast to the FDA warning, this study found no association between citalopram/escitalopram dose and QTc. However, PM of the drug tended to have longer QTc intervals. Our findings suggest cytochrome P450 genotyping in select patients may be helpful to guide medication optimization while limiting harmful effects. © The Author(s) 2014.

[Polar S810 as an alternative resource to the use of the electrocardiogram in the 4-second exercise test].

PubMed

Pimentel, Alan Santos; Alves, Eduardo da Silva; Alvim, Rafael de Oliveira; Nunes, Rogério Tasca; Costa, Carlos Magno Amaral; Lovisi, Júlio Cesar Moraes; Perrout de Lima, Jorge Roberto

2010-05-01

The 4-second exercise test (T4s) evaluates the cardiac vagal tone during the initial heart rate (HR) transient at sudden dynamic exercise, through the identification of the cardiac vagal index (CVI) obtained from the electrocardiogram (ECG). To evaluate the use of the Polar S810 heart rate monitor (HRM) as an alternative resource to the use of the electrocardiogram in the 4-second exercise test. In this study, 49 male individuals (25 +/- 20 years, 176 +/-12 cm, 74 +/- 6 kg) underwent the 4-second exercise test. The RR intervals were recorded simultaneously by ECG and HRM. We calculated the mean and the standard deviation of the last RR interval of the pre-exercise period, or of the first RR interval of the exercise period, whichever was longer (RRB), of the shortest RR interval of the exercise period (RRC), and of the CVI obtained by ECG and HRM. We used the Student t-test for dependent samples (p < or 0.05) to test the significance of the differences between means. To identify the correlation between the ECG and the HRM, we used the linear regression to calculate the Pearson's correlation coefficient and the strategy proposed by Bland and Altman. Linear regression showed r(2) of 0.9999 for RRB, 0.9997 for RRC, and 0.9996 for CVI. Bland e Altman strategy presented standard deviation of 0.92 ms for RRB, 0.86 ms for RRC, and 0.002 for CVI. Polar S810 HRM was more efficient in the application of T4s compared to the ECG.

The role of repeating optimization of atrioventricular interval during interim and long-term follow-up after cardiac resynchronization therapy.

PubMed

Zhang, Qing; Fung, Jeffrey Wing-Hong; Chan, Yat-Sun; Chan, Hamish Chi-Kin; Lin, Hong; Chan, Skiva; Yu, Cheuk-Man

2008-02-29

Cardiac resynchronization therapy (CRT) is an effective therapy for heart failure patients with electromechanical delay. Optimization of atrioventricular interval (AVI) is a cardinal component for the benefits. However, it is unknown if the AVI needs to be re-optimized during long-term follow-up. Thirty-one patients (66+/-11 years, 20 males) with sinus rhythm who received CRT underwent serial optimization of AVI at day 1, 3-month and during long-term follow-up by pulse Doppler echocardiography (PDE). At long-term follow-up, the optimal AVI and cardiac output (CO) estimated by non-invasive impedance cardiography (ICG) were compared with those by PDE. The follow-up was 16+/-11 months. There was no significant difference in the mean optimal AVI when compared between any 2 time points among day 1 (99+/-30 ms), 3-month (97+/-28 ms) and long-term follow-up (94+/-28 ms). However, in individual patient, the optimal AVI remained unchanged only in 14 patients (44%), and was shortened in 12 (38%) and lengthened in 6 patients (18%). During long-term follow-up, although the mean optimal AVIs obtained by PDE or ICG (94+/-28 vs. 92+/-29 ms) were not different, a discrepancy was found in 14 patients (45%). For the same AVI, the CO measured by ICG was systematically higher than that by PDE (3.5+/-0.8 Vs. 2.7+/-0.6 L/min, p<0.001). Optimization of AVI after CRT appears necessary during follow-up as it was readjusted in 55% of patients. Although AVI optimization by ICG was feasible, further studies are needed to confirm its role in optimizing AVI after CRT.

Superthermal (0.5- 100 keV) Electrons near the ICME-driven shocks

NASA Astrophysics Data System (ADS)

Yang, L.; Wang, L.; Li, G.; Tao, J.; He, J.; Tu, C.

2016-12-01

We present a survey of the 0.5 - 100 keV electrons associated with ICME-driven shocks at 1 AU, using the WIND/3DP electron measurements from 1995 to 2014. We select 66 good ICME-driven shocks, and use the "Rankine-Hugoniot" shock fitting technique to obtain the shock normal, shock velocity Vs, shock compression ratio r and magnetosonic Mach number Ms. We average the electron data in the 1-hour interval immediately after the shock front to obtain the sheath electron fluxes and in the 4-hour quiet-time interval before the shock to obtain the pre-event electron fluxes. Then we subtract the pre-event electron fluxes from the sheath electron fluxes to obtain the enhanced electron fluxes at the shock. We find that the enhanced electron fluxes are positively correlated with Vs and Ms, and generally fit well to a double power-law spectrum, J E-β. At 0.5 - 2 keV, the fitted spectral index β1 ranges from 2.1 to 5.9, negatively correlated with r and Ms. At 2 - 100 keV, the fitted index β2 is smaller than β1, with values ( 1.9 to 3.4) similar to the spectral indexes of quiet-time superhalo electrons in the solar wind. β2 shows no obvious correlation with r and Ms. Neither of β1 or β2 is in agreement with the diffusive shock theoretical predication. These results suggest that electron acceleration by interplanetary shocks may be more significant at a few keVs and the interplanetary shock acceleration can contribute to the production of solar wind superhalo electrons. However, a revision of the diffusive shock acceleration theory would be needed for the electron acceleration.

Bromazepam determination in human plasma by high-performance liquid chromatography coupled to tandem mass spectrometry: a highly sensitive and specific tool for bioequivalence studies.

PubMed

Laurito, Tiago L; Mendes, Gustavo D; Santagada, Vincenzo; Caliendo, Giuseppe; de Moraes, Maria Elisabete A; De Nucci, Gilberto

2004-02-01

A rapid, sensitive and specific method to quantify bromazepam in human plasma using diazepam as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using diethyl ether-hexane (80 : 20, v/v). The extracts were analyzed by high-performance liquid chromatography (HPLC) coupled to electrospray tandem mass spectrometry (MS/MS). Chromatography was performed isocratically on a Genesis C(18) analytical column (100 x 2.1 mm i.d., film thickness 4 microm). The method had a chromatographic run time of 5.0 min and a linear calibration curve over the range 5.0-150 ng ml(-1) (r(2) > 0.9952). The limit of quantification was 5 ng ml(-1). This HPLC/MS/MS procedure was used to assess the bioequivalence of two bromazepam 6 mg tablet formulations (bromazepam from Medley SA Indústria Farmacêutica as the test formulation and Lexotan from Produtos Roche Químico e Farmacêutico SA as the reference formulation). A single 6 mg dose of each formulation was administered to 24 healthy volunteers (12 males and 12 females). The study was conducted using an open, randomized, two-period crossover design with a 3 week washout interval. Since the 90% CI for C(max), AUC(last), AUC(0-240 h) (linear) and AUC((0- infinity )) ratios were all inside the 80-125% interval proposed by the US Food and Drug Administration, it was concluded that the bromazepam formulation from Medley is bioequivalent to the Lexotan formulation for both the rate and the extent of absorption. Copyright 2004 John Wiley & Sons, Ltd.

Effects of a pretarget distractor on saccade reaction times across space and time in monkeys and humans

PubMed Central

Khan, Aarlenne Z.; Munoz, Douglas P.; Takahashi, Naomi; Blohm, Gunnar; McPeek, Robert M.

2016-01-01

Previous studies have shown that the influence of a behaviorally irrelevant distractor on saccade reaction times (SRTs) varies depending on the temporal and spatial relationship between the distractor and the saccade target. We measured distractor influence on SRTs to a subsequently presented target, varying the spatial location and the timing between the distractor and the target. The distractor appeared at one of four equally eccentric locations, followed by a target (either 50 ms or 200 ms after) at one of 136 different locations encompassing an area of 20° square. We extensively tested two humans and two monkeys on this task to determine interspecies similarities and differences, since monkey neurophysiology is often used to interpret human behavioral findings. Results were similar across species; for the short interval (50 ms), SRTs were shortest to a target presented close to or at the distractor location and increased primarily as a function of the distance from the distractor. There was also an effect of distractor-target direction and visual field. For the long interval (200 ms) the results were inverted; SRTs were longest for short distances between the distractor and target and decreased as a function of distance from distractor. Both SRT patterns were well captured by a two-dimensional dynamic field model with short-distance excitation and long-distance inhibition, based upon known functional connectivity found in the superior colliculus that includes wide-spread excitation and inhibition. Based on these findings, we posit that the different time-dependent patterns of distractor-related SRTs can emerge from the same underlying neuronal mechanisms common to both species. PMID:27148697

Abnormal frontal theta oscillations underlie the cognitive flexibility deficits in children with high-functioning autism spectrum disorders.

PubMed

Yeung, Michael K; Han, Yvonne M Y; Sze, Sophia L; Chan, Agnes S

2016-03-01

Deficits in cognitive flexibility have been suggested to underlie the repetitive and stereotyped behavior in individuals with autism spectrum disorders (ASD). Because cognitive flexibility is primarily mediated by the frontal lobe, where structural and functional abnormalities have been extensively found in these individuals, it is conceivable that their deficits in cognitive flexibility are related to abnormal activations of the frontal lobe. The present study investigates cognitive flexibility and its underlying neurophysiological activities as indicated by theta oscillations in children with ASD. Twenty-five children with high-functioning ASD and 25 IQ- and age-matched typically developing (TD) children were subjected to neuropsychological assessments on cognitive flexibility and electroencephalography recordings. The children with ASD performed significantly worse than the TD children across the tasks of cognitive flexibility, including the modified Wisconsin Card Sorting Test (WCST). These children also demonstrated a reduced increase of the theta power localized in multiple brain regions, including various sectors of the frontal lobe at the late stage (i.e., 600 ms-900 ms poststimulus interval) but not the early stage (i.e., 250 ms-550 ms poststimulus interval) of the performance of the modified WCST. The suppressed late frontal theta activities were further shown to be significantly correlated with a poorer performance on the cognitive flexibility measures. Our findings suggest that abnormal activations of multiple cortical regions, especially the frontal lobe, form the neural basis of the cognitive flexibility deficits in children with ASD. In addition, we found an EEG marker of cognitive flexibility which could be used to monitor treatment outcomes objectively. (c) 2016 APA, all rights reserved).

Determination of baroreflex gain using auto-regressive moving-average analysis during spontaneous breathing.

PubMed

O'Leary, D D; Lin, D C; Hughson, R L

1999-09-01

The heart rate component of the arterial baroreflex gain (BRG) was determined with auto-regressive moving-average (ARMA) analysis during each of spontaneous (SB) and random breathing (RB) protocols. Ten healthy subjects completed each breathing pattern on two different days in each of two different body positions, supine (SUP) and head-up tilt (HUT). The R-R interval, systolic arterial pressure (SAP) and instantaneous lung volume were recorded continuously. BRG was estimated from the ARMA impulse response relationship of R-R interval to SAP and from the spontaneous sequence method. The results indicated that both the ARMA and spontaneous sequence methods were reproducible (r = 0.76 and r = 0.85, respectively). As expected, BRG was significantly less in the HUT compared to SUP position for both ARMA (mean +/- SEM; 3.5 +/- 0.3 versus 11.2 +/- 1.4 ms mmHg-1; P < 0.01) and spontaneous sequence analysis (10.3 +/- 0.8 versus 31.5 +/- 2.3 ms mmHg-1; P < 0.001). However, no significant difference was found between BRG during RB and SB protocols for either ARMA (7.9 +/- 1.4 versus 6.7 +/- 0.8 ms mmHg-1; P = 0.27) or spontaneous sequence methods (21.8 +/- 2.7 versus 20.0 +/- 2.1 ms mmHg-1; P = 0.24). BRG was correlated during RB and SB protocols (r = 0.80; P < 0.0001). ARMA and spontaneous BRG estimates were correlated (r = 0.79; P < 0.0001), with spontaneous sequence values being consistently larger (P < 0.0001). In conclusion, we have shown that ARMA-derived BRG values are reproducible and that they can be determined during SB conditions, making the ARMA method appropriate for use in a wider range of patients.

Differentiation of ventricular and supraventricular tachycardias based on the analysis of the first postpacing interval after sequential anti-tachycardia pacing in implantable cardioverter-defibrillator patients.

PubMed

Arenal, Angel; Ortiz, Mercedes; Peinado, Rafael; Merino, Jose L; Quesada, Aurelio; Atienza, Felipe; Alberola, Arcadio García; Ormaetxe, Jose; Castellanos, Eduardo; Rodriguez, Juan C; Pérez, Nicasio; García, Javier; Boluda, Luis; del Prado, Mario; Artés, Antonio

2007-03-01

Current discrimination algorithms do not completely avoid inappropriate tachycardia detection. This study analyzes the discrimination capability of the changes of the first postpacing interval (FPPI) after successive bursts of anti-tachycardia pacing (ATP) trains in implantable cardioverter-defibrillator (ICD)-recorded tachycardias. We included 50 ICD patients in this prospective study. We hypothesized that the FPPI variability (FPPIV) when comparing bursts with different numbers of beats would be shorter in ventricular tachycardias (VTs) compared with supraventricular tachycardias (SVTs). The ATP (5-10 pulses, 91% of tachycardia cycle length) was programmed for tachycardias >240 ms. Anti-tachycardia pacing was delivered during 37 sinus tachycardias (STs) in an exercise test, 96 induced VTs in an electrophysiological study, and 198 spontaneous episodes (144 VTs and 54 SVTs). The FPPI remained stable after all ATP bursts in VT but changed continuously in SVT; when comparing bursts of 5 and 10 pulses, the FPPIV was shorter in VT (34 +/- 65 vs.138 +/- 69, P<.0001, in all T and 12 +/- 20 vs. 138 +/- 69, P<.0001, in T>or=320 ms) than in SVT. In T>or=320 ms an FPPIV

Parental determinants of metabolic syndrome among adolescent Asian Indians: A cross-sectional analysis of parent-offspring trios.

PubMed

Baxi, Rahul; Vasan, Senthil K; Hansdak, Samuel; Samuel, Prasanna; Jeyaseelan, Visali; Geethanjali, Finney S; Murray, Ruth R; Venkatesan, Padmanaban; Thomas, Nihal

2016-07-01

The aim of the present study was to investigate the relationship between parental metabolic syndrome (MS) and the risk of MS and associated abnormalities in adolescent offspring. This cross-sectional study was performed on 304 adolescents (12-16 years; 236 children with at least one parent and 124 father-mother-child trios) recruited from four schools representing different socioeconomic strata from Vellore, India. Anthropometric data was collected and blood pressure, blood glucose, and lipids were measured. The prevalence of MS in adolescent offspring, fathers, and mothers was 3.3%, 52.5%, and 48.7% respectively. The most commonly observed metabolic abnormality among adolescents was lower high-density lipoprotein. Maternal waist circumference (WC) was strongly correlated with adolescent body mass index (P = 0.007), WC (P < 0.001), serum triglycerides (P = 0.02), and systolic (P = 0.005) and diastolic (P = 0.01) blood pressure. Maternal MS status was significantly associated with a greater risk of central obesity (WC odds ratio [OR] 2.02; 95% confidence interval [CI] 1.21-3.17) in offspring. Both parents having MS conferred a significant effect on the child's WC (OR 1.21; 95% CI 1.72-2.07) and increased risk of MS (OR 6.19; 95% CI 1.64-23.26). This study highlights the possible heritable parental components that may contribute to the MS phenotype in offspring: MS in adolescent offspring is related to parental MS status, and maternal traits reflect offspring adiposity and metabolic traits more strongly than paternal factors. Therefore, adolescent children of parents with MS should be targets for primordial prevention of cardiometabolic disease. © 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

The Symbol Digit Modalities Test is an effective cognitive screen in pediatric onset multiple sclerosis (MS).

PubMed

Charvet, Leigh E; Beekman, Rachel; Amadiume, Nneka; Belman, Anita L; Krupp, Lauren B

2014-06-15

To evaluate the Symbol Digit Modalities Test (SDMT) as a tool for identifying pediatric-onset MS patients at risk for cognitive impairment. The SDMT is a brief measure of cognitive processing speed that is often used in adult MS patients. Approximately one-third of pediatric-onset MS patients have cognitive impairment and there is a need for an effective screening instrument. Seventy (70) consecutive outpatients with pediatric-onset MS underwent clinical evaluations including the SDMT and were compared to those with other pediatric neurological diagnoses (OND, n=40) and healthy controls (HC, n=32). A subset of the MS group and all healthy controls completed neuropsychological evaluation within one year of SDMT administration. The MS group performed worse on the SDMT compared to the HC group (p=0.02). Thirty-seven percent (37%) of the MS, 20% of the OND, and 9% of HC groups scored in the impaired range. For MS participants who underwent neuropsychological testing (n=31), the SDMT showed 77% sensitivity and 81% specificity for detecting neuropsychological impairment when administered within one year and reached 100% sensitivity when the interval was under two months (n=17). Overall, older age and increased disability predicted poorer SDMT performance (age r=-0.26, p=0.03) and the Expanded Disability Status Scale score or EDSS (r=-0.47, p<0.001), while a history of optic neuritis predicted better performance (p=0.04). Optical coherence tomography measures were not related to SDMT performance. In this preliminary study, the SDMT was an effective brief screen for detecting cognitive impairment in pediatric-onset MS. Copyright © 2014 Elsevier B.V. All rights reserved.

Sun exposure over the life course and associations with multiple sclerosis.

PubMed

Tremlett, Helen; Zhu, Feng; Ascherio, Alberto; Munger, Kassandra L

2018-04-03

To examine sun exposure and multiple sclerosis (MS) over the life course (ages 5-15 and 16-20 years, every 10 years thereafter). Cases with MS (n = 151) and age-matched controls (n = 235) from the Nurses' Health Study cohorts completed summer, winter, and lifetime sun exposure history questionnaires. Cumulative ambient ultraviolet (UV)-B (based on latitude, altitude, cloud cover) exposure before MS onset was expressed as tertiles. Seasonal sun exposure was defined as low vs high hours per week (summer [≤9 vs >10 h/wk]; winter [≤3 vs >4 h/wk]). Relative risks (RRs) and 95% confidence intervals (CIs) were estimated via conditional logistic regression with adjustment for body mass index, ancestry, smoking, and vitamin D supplementation. Most participants were white (98%); the mean age at MS onset was 39.5 years. Living in high (vs low) UV-B areas before MS onset was associated with a 45% lower MS risk (adjusted RR 0.55, 95% CI 0.42-0.73). Similar reduced risks (51%-52%) for medium or high exposure were observed at ages 5 to 15 years and at 5 to 15 years before MS onset (adjusted p < 0.05). At age 5 to 15 years, living in a high (vs low) UV-B area and having high (vs low) summer sun exposure were associated with a lower MS risk (RR 0.45, 95% CI 0.21-0.96). Living in high ambient UV-B areas during childhood and the years leading up to MS onset was associated with a lower MS risk. High summer sun exposure in high ambient UV-B areas was also associated with a reduced risk. © 2018 American Academy of Neurology.

Cognitive function did not improve after initiation of natalizumab treatment in relapsing-remitting multiple sclerosis. A prospective one-year dual control group study.

PubMed

Sundgren, M; Piehl, Fredrik; Wahlin, Åke; Brismar, Tom

2016-11-01

Cognitive impairment in multiple sclerosis (MS) is common and has severe implications. Natalizumab (NZ) has documented effects on relapse rate and radiological disease activity in relapsing-remitting MS (RRMS) but studies regarding its specific effects on cognitive functioning are few. Previous studies have reported improvement, however, often lacking relevant control groups. The objective of the present study was to evaluate the cognitive effects of NZ treatment, compared to patients on stable first-line treatment and healthy control subjects. MS patients starting NZ (MS-NZ), MS controls with stable interferon beta therapy (MS-C) and healthy control subjects (HC) were evaluated twice with one year interval, using a cognitive test battery covering six cognitive domains. The effects of NZ on levels of self-reported depression, fatigue, daytime sleepiness and perceived health were also examined. MS patients (MS-NZ and MS-C) had significantly lower baseline cognitive performance compared to HC (global score, p=0.002), but there were no significant differences between MS-NZ and MS-C. At follow-up, both MS-NZ and MS-C had improved significantly in four and five cognitive domains, respectively, and in global score (p=0.013 and p<0.001, respectively). HC improved significantly in three cognitive domains but not in global score. A regression analysis including baseline cognitive z-score and z-score change showed that participants with lower baseline scores had a significantly greater improvement, compared to those with better initial performance (p=0.021). There were no significant changes in depression, fatigue, daytime sleepiness or perceived health in MS-NZ or MS-C. Initiation of NZ therapy did not result in true cognitive improvement over one year. Presumably, the increased test performance in both MS groups was artificial and due to retest effects that were stronger in patients with lower baseline performance. Adequate control groups are essential when evaluating cognitive functioning in intervention trials among RRMS patients. Copyright © 2016 Elsevier B.V. All rights reserved.

Infant auditory short-term memory for non-linguistic sounds.

PubMed

Ross-Sheehy, Shannon; Newman, Rochelle S

2015-04-01

This research explores auditory short-term memory (STM) capacity for non-linguistic sounds in 10-month-old infants. Infants were presented with auditory streams composed of repeating sequences of either 2 or 4 unique instruments (e.g., flute, piano, cello; 350 or 700 ms in duration) followed by a 500-ms retention interval. These instrument sequences either stayed the same for every repetition (Constant) or changed by 1 instrument per sequence (Varying). Using the head-turn preference procedure, infant listening durations were recorded for each stream type (2- or 4-instrument sequences composed of 350- or 700-ms notes). Preference for the Varying stream was taken as evidence of auditory STM because detection of the novel instrument required memory for all of the instruments in a given sequence. Results demonstrate that infants listened longer to Varying streams for 2-instrument sequences, but not 4-instrument sequences, composed of 350-ms notes (Experiment 1), although this effect did not hold when note durations were increased to 700 ms (Experiment 2). Experiment 3 replicates and extends results from Experiments 1 and 2 and provides support for a duration account of capacity limits in infant auditory STM. Copyright © 2014 Elsevier Inc. All rights reserved.

Event-related potential measures of gap detection threshold during natural sleep.

PubMed

Muller-Gass, Alexandra; Campbell, Kenneth

2014-08-01

The minimum time interval between two stimuli that can be reliably detected is called the gap detection threshold. The present study examines whether an unconscious state, natural sleep affects the gap detection threshold. Event-related potentials were recorded in 10 young adults while awake and during all-night sleep to provide an objective estimate of this threshold. These subjects were presented with 2, 4, 8 or 16ms gaps occurring in 1.5 duration white noise. During wakefulness, a significant N1 was elicited for the 8 and 16ms gaps. N1 was difficult to observe during stage N2 sleep, even for the longest gap. A large P2 was however elicited and was significant for the 8 and 16ms gaps. Also, a later, very large N350 was elicited by the 16ms gap. An N1 and P2 was significant only for the 16ms gap during REM sleep. ERPs to gaps occurring in noise segments can therefore be successfully elicited during natural sleep. The gap detection threshold is similar in the waking and sleeping states. Crown Copyright © 2014. Published by Elsevier Ireland Ltd. All rights reserved.

[Positive potentials of the human brain at different stages of preparation of a visually triggered saccade].

PubMed

Slavutskaia, M V; Shul'govskiĭ, V V

2003-01-01

The EEG of 10 right-handed subjects preceding saccades with mean values of latent periods were selected and averaged. Two standard paradigms of presentation of visual stimuli (central fixation stimulus-peripheral target succession): with a 200-ms inerstimulus interval (GAP) and successive single step (SS). During the period of central fixation, two kinds of positive potentials were observed: fast potentials of "inermediate" positivity (IP) developing 600-400 ms prior to saccade onset and fast potentials of "leading" positivity (LP), which immediately preceded the offset of the central fixation stimulus. Peak latency of the LP potentials was 300 ms prior to saccade onset in the SS paradigm and 400 ms in the GAP paradigm. These potentials were predominantly recorded in the frontal and frontosagittal cortical areas. Decrease in the latency by 30-50 ms in the GAP paradigm was associated with more pronounced positive potentials during the fixation period and absence of the initiation potential P-1' (or decrease in its amplitude). The obtained evidence suggest that the fast positive presaccadic potentials are of a complex nature related to attention, anticipation, motor preparation, decision making, saccadic initiation, and backward afferentation.

Validation of a classification system to grade fractionation in atrial fibrillation and correlation with automated detection systems.

PubMed

Hunter, Ross J; Diab, Ihab; Thomas, Glyn; Duncan, Edward; Abrams, Dominic; Dhinoja, Mehul; Sporton, Simon; Earley, Mark J; Schilling, Richard J

2009-12-01

We tested application of a grading system describing complex fractionated electrograms (CFE) in atrial fibrillation (AF) and used it to validate automated CFE detection (AUTO). Ten seconds bipolar electrograms were classified by visual inspection (VI) during ablation of persistent AF and the result compared with offline manual measurement (MM) by a second blinded operator: Grade 1 uninterrupted fractionated activity (defined as segments > or =70 ms) for > or =70% of recording and uninterrupted > or =1 s; Grade 2 interrupted fractionated activity > or =70% of recording; Grade 3 intermittent fractionated activity 30-70%; Grade 4 discrete (<70 ms) complex electrogram (> or =5 direction changes); Grade 5 discrete simple electrograms (< or =4 direction changes); Grade 6 scar. Grade by VI and MM for 100 electrograms agreed in 89%. Five hundred electrograms were graded on Carto and NavX by VI to validate AUTO in (i) detection of CFE (grades 1-4 considered CFE), and (ii) assessing degree of fractionation by correlating grade and score by AUTO (data shown as sensitivity, specificity, r): NavX 'CFE mean' 92%, 91%, 0.56; Carto 'interval confidence level' using factory settings 89%, 62%, -0.72, and other published settings 80%, 74%, -0.65; Carto 'shortest confidence interval' 74%, 70%, 0.43; Carto 'average confidence interval' 86%, 66%, 0.53. Grading CFE by VI is accurate and correlates with AUTO.

Benchmark of multi-phase method for the computation of fast ion distributions in a tokamak plasma in the presence of low-amplitude resonant MHD activity

NASA Astrophysics Data System (ADS)

Bierwage, A.; Todo, Y.

2017-11-01

The transport of fast ions in a beam-driven JT-60U tokamak plasma subject to resonant magnetohydrodynamic (MHD) mode activity is simulated using the so-called multi-phase method, where 4 ms intervals of classical Monte-Carlo simulations (without MHD) are interlaced with 1 ms intervals of hybrid simulations (with MHD). The multi-phase simulation results are compared to results obtained with continuous hybrid simulations, which were recently validated against experimental data (Bierwage et al., 2017). It is shown that the multi-phase method, in spite of causing significant overshoots in the MHD fluctuation amplitudes, accurately reproduces the frequencies and positions of the dominant resonant modes, as well as the spatial profile and velocity distribution of the fast ions, while consuming only a fraction of the computation time required by the continuous hybrid simulation. The present paper is limited to low-amplitude fluctuations consisting of a few long-wavelength modes that interact only weakly with each other. The success of this benchmark study paves the way for applying the multi-phase method to the simulation of Abrupt Large-amplitude Events (ALE), which were seen in the same JT-60U experiments but at larger time intervals. Possible implications for the construction of reduced models for fast ion transport are discussed.

Consideration of computer limitations in implementing on-line controls. M.S. Thesis

NASA Technical Reports Server (NTRS)

Roberts, G. K.

1976-01-01

A formal statement of the optimal control problem which includes the interval of dicretization as an optimization parameter, and extend this to include selection of a control algorithm as part of the optimization procedure, is formulated. The performance of the scalar linear system depends on the discretization interval. Discrete-time versions of the output feedback regulator and an optimal compensator, and the use of these results in presenting an example of a system for which fast partial-state-feedback control better minimizes a quadratic cost than either a full-state feedback control or a compensator, are developed.

Quasi-steady carbon plasma source for neutral beam injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koguchi, H., E-mail: h-koguchi@aist.go.jp; Sakakita, H.; Kiyama, S.

2014-02-15

Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

Quasi-steady carbon plasma source for neutral beam injector.

PubMed

Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

2014-02-01

Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

Evolution of the magnetic field structure of the Crab pulsar.

PubMed

Lyne, Andrew; Graham-Smith, Francis; Weltevrede, Patrick; Jordan, Christine; Stappers, Ben; Bassa, Cees; Kramer, Michael

2013-11-01

Pulsars are highly magnetized rotating neutron stars and are well known for the stability of their signature pulse shapes, allowing high-precision studies of their rotation. However, during the past 22 years, the radio pulse profile of the Crab pulsar has shown a steady increase in the separation of the main pulse and interpulse components at 0.62° ± 0.03° per century. There are also secular changes in the relative strengths of several components of the profile. The changing component separation indicates that the axis of the dipolar magnetic field, embedded in the neutron star, is moving toward the stellar equator. This evolution of the magnetic field could explain why the pulsar does not spin down as expected from simple braking by a rotating dipolar magnetic field.

Femtosecond laser-induced periodic surface structures on silicon upon polarization controlled two-color double-pulse irradiation.

PubMed

Höhm, Sandra; Herzlieb, Marcel; Rosenfeld, Arkadi; Krüger, Jörg; Bonse, Jörn

2015-01-12

Two-color double-fs-pulse experiments were performed on silicon wafers to study the temporally distributed energy deposition in the formation of laser-induced periodic surface structures (LIPSS). A Mach-Zehnder interferometer generated parallel or cross-polarized double-pulse sequences at 400 and 800 nm wavelength, with inter-pulse delays up to a few picoseconds between the sub-ablation 50-fs-pulses. Multiple two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample. The resulting LIPSS characteristics (periods, areas) were analyzed by scanning electron microscopy. A wavelength-dependent plasmonic mechanism is proposed to explain the delay-dependence of the LIPSS. These two-color experiments extend previous single-color studies and prove the importance of the ultrafast energy deposition for LIPSS formation.

Modeling laser-induced periodic surface structures: Finite-difference time-domain feedback simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skolski, J. Z. P., E-mail: j.z.p.skolski@utwente.nl; Vincenc Obona, J.; Römer, G. R. B. E.

2014-03-14

A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by “ablation after each laser pulse,” according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to “grow” either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelengthmore » of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.« less

An online open-source tool for automated quantification of liver and myocardial iron concentrations by T2* magnetic resonance imaging.

PubMed

Git, K-A; Fioravante, L A B; Fernandes, J L

2015-09-01

To assess whether an online open-source tool would provide accurate calculations of T2(*) values for iron concentrations in the liver and heart compared with a standard reference software. An online open-source tool, written in pure HTML5/Javascript, was tested in 50 patients (age 26.0 ± 18.9 years, 46% males) who underwent T2(*) MRI of the liver and heart for iron overload assessment as part of their routine workup. Automated truncation correction was the default with optional manual adjustment provided if needed. The results were compared against a standard reference measurement using commercial software with manual truncation (CVI(42)(®) v. 5.1; Circle Cardiovascular Imaging; Calgary, AB). The mean liver T2(*) values calculated with the automated tool was 4.3 ms [95% confidence interval (CI) 3.1 to 5.5 ms] vs 4.26 ms using the reference software (95% CI 3.1 to 5.4 ms) without any significant differences (p = 0.71). In the liver, the mean difference was 0.036 ms (95% CI -0.1609 to 0.2329 ms) with a regression correlation coefficient of 0.97. For the heart, the automated T2(*) value was 26.0 ms (95% CI 22.9 to 29.0 ms) vs 25.3 ms (95% CI 22.3 to 28.3 ms), p = 0.28. The mean difference was 0.72 ms (95% CI 0.08191 to 1.3621 ms) with a correlation coefficient of 0.96. The automated online tool provides similar T2(*) values for the liver and myocardial iron concentrations as compared with a standard reference software. The online program provides an open-source tool for the calculation of T2(*) values, incorporating an automated correction algorithm in a simple and easy-to-use interface.

Notes on the Epidemiology of Multiple Sclerosis, with Special Reference to Dietary Habits

PubMed Central

Lauer, Klaus

2014-01-01

A hypothesis, based primarily on the occurrence of multiple sclerosis (MS) in the Faroe Islands and supported by numerous analytical epidemiological studies, is described. It proposes that MS is caused by the interaction of a virus disease with intestinal pathology, e.g., infectious mononucleosis, and application of smoked and nitrate/nitrite-cured meat products in the diet during circumscribed time intervals. The biological mechanisms might involve a break of tolerance by an alteration of self within the central nervous system, by nitrophenylated compounds conjugated to animal tissue, in particular to proteins occurring in the central nervous system. Further research is needed. PMID:24577315

Attentional and Perceptual Factors Affecting the Attentional Blink for Faces and Objects

ERIC Educational Resources Information Center

Landau, Ayelet N.; Bentin, Shlomo

2008-01-01

When 2 different visual targets presented among different distracters in a rapid serial visual presentation (RSVP) are separated by 400 ms or less, detection and identification of the 2nd targets are reduced relative to longer time intervals. This phenomenon, termed the "attentional blink" (AB), is attributed to the temporary engagement…

Rhythms that Speed You Up

ERIC Educational Resources Information Center

Sanabria, Daniel; Capizzi, Mariagrazia; Correa, Angel

2011-01-01

This study investigates whether a rhythm can orient attention to specific moments enhancing people's reaction times (RT). We used a modified version of the temporal orienting paradigm in which an auditory isochronous rhythm was presented prior to an auditory single target. The rhythm could have a fast pace (450 ms Inter-Onset-Interval or IOI) or a…

Atropine unmasks bed-rest effect - A spectral analysis of cardiac interbeat intervals

NASA Technical Reports Server (NTRS)

Goldberger, Ary L.; Goldwater, Danielle; Bhargava, Valmik

1986-01-01

Heart rate spectral data obtained for 10 male subjects between 35-49 years following orthostatic tolerance testing with lower body negative pressure prebed rest and after 7-10 days of bed rest, while on placebo and after intravenous atropine are analyzed. Comparison of the spectral atropine rms for subjects prebed rest and after bed rest reveal a decrease from 63 + or - 24 ms to 40 + or - 23 ms. It is observed that heart rate interval variability for subjects after bed rest and with atropine is reduced; the heart rate at bed rest with atropine is increased from 70.4 + or - 12.4 beats/min prebed rest to 83.7 + or - 18.9 beats/min; and the exercise tolerance time for subjects in the atropine prebed-rest phase (658 + or - 352 s) is higher than the bed-rest phase (505 + or - 252 s). It is noted that bed rest impairs the cardiovascular capacity to adaptively modulate physiological responses, atropine exposes bed-rest deconditioning effects, and spectral analysis is useful for studying the effects of bed-rest deconditioning on cardiac dynamics.

Reduced surround inhibition in musicians.

PubMed

Shin, Hae-Won; Kang, Suk Y; Hallett, Mark; Sohn, Young H

2012-06-01

To investigate whether surround inhibition (SI) in the motor system is altered in professional musicians, we performed a transcranial magnetic stimulation (TMS) study in 10 professional musicians and 15 age-matched healthy non-musicians. TMS was set to be triggered by self-initiated flexion of the index finger at different intervals ranging from 3 to 1,000 ms. Average motor evoked potential (MEP) amplitudes obtained from self-triggered TMS were normalized to average MEPs of the control TMS at rest and expressed as a percentage. Normalized MEP amplitudes of the abductor digiti minimi (ADM) muscles were compared between the musicians and non-musicians with the primary analysis being the intervals between 3 and 80 ms (during the movement). A mixed-design ANOVA revealed a significant difference in normalized ADM MEPs during the index finger flexion between groups, with less SI in the musicians. This study demonstrated that the functional operation of SI is less strong in musicians than non-musicians, perhaps due to practice of movement synergies involving both muscles. Reduced SI, however, could lead susceptible musicians to be prone to develop task-specific dystonia.

Validation of a confirmatory method for the determination of residues of four nitrofurans in egg by liquid chromatography-tandem mass spectrometry with the software InterVal.

PubMed

Bock, C; Stachel, C; Gowik, P

2007-03-14

A method for the detection and determination of nitrofuran derivatives in egg by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was validated with the software InterVal and can be applied for the confirmation of nitrofuran metabolites in fresh or lyophilised eggs. The validation study comprises variations in operator, storage condition, breeding, equipment and duration of sample preparation. A comprehensive overview of the robustness of the method is obtained by analysing eight samples at six concentration levels. First results of short- and medium-term investigations for stability of analytes in solution show that standard solutions of nitrofuran metabolites are stable for at least 1 year when stored at +4 degrees C in the dark. The decision limit CCalpha expressed for the underivatised metabolite is 0.05 microg kg(-1) for 3-amino-5-methyl-morpholino-2-oxazolidinone, 0.03 microg kg(-1) for 3-amino-2-oxazolidinone, 0.20 microg kg(-1) for semicarbazide and 0.22 microg kg(-1) for 1-amino-hydantoin.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

PubMed

Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

2018-02-13

Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no statistically significant differences between these sub-groups or between conditions when the data were pooled. Based on the present results there is insufficient evidence to conclude that patellar tendon vibration provides a clear benefit to muscle force production or delays muscle fatigue during wide-pulse width, moderate-intensity NMES in people with SCI. ACTRN12618000022268 . Date: 11/01/2018. Retrospectively registered.