Sec Duration Research Articles

Amplitude-dependency of response of SI cortex to flutter stimulation

BackgroundIt is established that increasing the amplitude of a flutter stimulus increases its perceived intensity. Although many studies have examined this phenomenon with regard to the responding afferent population, the way in which the intensity of a stimulus is coded in primary somatosensory cortex (SI) remains unclear.ResultsOptical intrinsic signal (OIS) imaging was used to study the evoked responses in SI of anesthetized squirrel monkeys by 25 Hz sinusoidal vertical skin displacement stimulation. Stimuli were 10 sec duration with a 50 sec inter-stimulus interval. Stimulus amplitude ranged from 50 to 400 microns and different amplitudes were interleaved. Control levels of activity were measured in the absence of stimulation, and used to compare with activation levels evoked by the different stimulus amplitudes. Stimulation of a discrete skin site on the forelimb evoked a prominent increase in absorbance within the forelimb representational region in cytoarchitectonic areas 3b and 1 of the contralateral hemisphere. An increase in stimulus amplitude led to a proportional increase in the magnitude of the absorbance increase in this region of areas 3b and 1 while surrounding cortex underwent a decrease in absorbance. Correlation maps revealed that as stimulus amplitude is increased, the spatial extent of the activated region in SI remains relatively constant, and the activity within this region increases progressively. Additionally, as stimulus amplitude is increased to suprathreshold levels, activity in the surround of the activated SI territory decreases, suggesting an increase in inhibition of neuronal activity within these regions.ConclusionIncreasing the amplitude of a flutter stimulus leads to a proportional increase in absorbance within the forelimb representational region of SI. This most likely reflects an increase in the firing rate of neurons in this region of SI. The relatively constant spatial extent of this stimulus-evoked increase in absorbance suggests that an increase in the amplitude of a 25 Hz skin stimulus does not evoke a larger area of SI neuronal activation due to an amplitude-dependent lateral inhibitory effect that spatially funnels the responding SI neuronal population.

Enhanced sodium-calcium exchange enabled by an increase in the calcium transient in the presence of an abbreviated action potential: A new arrhythmia mechanism

Early afterdepolarizations (EADs) are observed in superfused canine pulmonary vein sleeves following norepinephrine (NE) (3.2 x 10−8 M) administration and tachycardia-pause pacing, interventions increasing the magnitude of the calcium transient. Further shortening of the already abbreviated pulmonary vein action potential by acetylcholine (10−7 M) enables the EADs to trigger arrhythmia formation. We examined the hypothesis that an increased calcium transient enhances an inward Na-Ca exchange current during late systole, and in the presence of an abbreviated action potential, serves as a basis for EADs and triggered arrhythmia. Using intracellular microelectrode recordings in superfused canine pulmonary vein sleeves, EADs were observed following NE administration (N= 18 of 23). EAD formation was pause-enhanced, following a single premature beat or a 5-20 beat (5.0 Hz) pacing train. Both EAD formation and triggered arrhythmia were suppressed by ryanodine administration (10 μM for 10 min), an intervention suppressing the calcium transient. EAD formation with pacing was enhanced by facilitation of Na-Ca exchange (forward mode)(reintroduction of 140 mM Nao following superfusion with 30 mM NaCl substituted with LiCl) and was suppressed by an acute increase in Cao from 1.35 to 5 mM, an intervention decreasing inward Na-Ca exchange. Triggering of rapid (¾800 bpm) sustained (¾1 sec in duration) arrhythmia was observed following acetylcholine administration in the presence of NE (N= 18 of 23).

Aerodynamic Entropy Generation Rate in a Boundary Layer With High Free Stream Turbulence

Aerodynamic Entropy Generation Rate in a Boundary Layer With High Free Stream Turbulence

Perirhinal cortex supports delay fear conditioning to rat ultrasonic social signals.

Auditory information can reach the lateral nucleus of the amygdala (LA) through a monosynaptic thalamic projection or a polysynaptic cortical route. The polymodal input from the perirhinal cortex (PR) is a major informational gateway to the LA and nearby structures. Pretraining PR lesions impair fear conditioning to a context, but there have been no reports that they cause deficits in delay conditioning to an auditory cue. The direct subcortical projection to the LA seems sufficient to support delay conditioning to a tone conditional stimulus (CS). We examined the effect of PR lesions on delay conditioning to two different tone conditional stimuli (4 and 22 kHz tones; both 10 sec duration) and two different rat ultrasonic vocalization (USV) conditional stimuli (10 sec of "22 kHz USVs"). The two USV conditional stimuli were multi-call segments that were recorded (digitized at 100 kHz) from two different rats. One USV CS was a continuous sequence of eight calls, and the other was a portion of a continuous sequence of six calls. PR lesions significantly impaired conditioning to both USV conditional stimuli and to the training context but had no significant effect on conditioning to either tone CS. The role of PR in fear conditioning appears not to be determined by whether the conditional stimuli serve as contexts or cues, but instead by the nature or complexity of the stimuli or stimulus configurations. These cue-specific effects of PR lesions are suggested to reflect differences in the stimulus features that are encoded in the two CS pathways to the LA.

Cholinergic Activity Enhances Hippocampal Long-Term Potentiation in CA1 during Walking in Rats

Long-term potentiation (LTP) at the basal-dendritic synapses of CA1 pyramidal cells was induced by a single 200 Hz stimulation train (0.5-1 sec duration) in freely behaving rats during one of four behavioral states: awake-immobility (IMM), walking, slow-wave sleep (SWS), and rapid eye movement sleep (REM). Field EPSPs generated by basal-dendritic excitation of CA1 were recorded before and up to 1 d after the tetanus. After a tetanus during any behavioral state, basal-dendritic LTP was >170% of the baseline for the first hour after the tetanus and decayed to approximately 120% 1 d after. LTP induced during walking was significantly larger than that induced during IMM, SWS, or REM, which had similar LTP magnitudes. To test the hypothesis that septohippocampal cholinergic activity enhanced LTP during walking as compared with IMM, rats were either pretreated with muscarinic cholinergic antagonist scopolamine or injected with IgG192-saporin in the medial septum to selectively lesion cholinergic septohippocampal neurons. Pretreatment with scopolamine decreased the LTP induced during walking but did not affect that induced during IMM, such that the difference between the LTP induced during walking and IMM was abolished after scopolamine. Rats injected with IgG192-saporin showed no difference in the LTP induced during walking and IMM, and scopolamine did not reduce the LTP during walking. In contrast, sham-lesion rats showed larger LTP induced during walking than IMM, and the LTP induced during walking was attenuated by scopolamine. This is the first demonstration of an enhancement of hippocampal LTP by physiologically activated cholinergic inputs.

Effect of somatostatin and galanin on isolated rabbit iris sphincter and dilator muscles

The neuropeptides somatostatin and galanin are present in the iris and may modulate pupil diameter. We examined the effects of somatostatin and galanin on isolated rabbit iris dilator and sphincter smooth muscles that were mounted in an organ bath. An isometric transducer recorded changes in tension in response to electric field stimulation (100 Hz, 0.3 m sec in duration, 10 V in strength) delivered by a pair of platinum plate electrodes. The dilator muscle response to field stimulation was not changed by either peptide, even at the highest concentrations examined. The sphincter muscle response consisted of two components: a fast component mediated by acetylcholine and slow component mediated by substance P. Both somatostatin and galanin attenuated the cholinergic component in a dose-dependent manner (from 0.3 n m to 0.1 μ m) but had no effect on responses mediated by substance P. Galanin was more effective (attenuation of 43% at 0.1 μ m) compared with somatostatin (attenuation of 16% at 0.1 μ m) in reducing the cholinergic response. Neither peptide affected the contraction induced by acetylcholine (1 m m). Therefore both peptides inhibited cholinergic transmission in the sphincter muscle, although the degree of inhibition by each was different. We conclude that somatostatin and/or galanin may induce mydriasis by attenuating cholinergic neurotransmitter release.

A NOVEL APPLICATION OF CONTACT FRICTION FOR LATERALLY MOTION TUNABLE ACCELERATION-THRESHOLD SWITCH: MODELING AND SIMULATION

International Journal of Computational Engineering ScienceVol. 04, No. 02, pp. 417-420 (2003) Design, Modelling and SimulationNo AccessA NOVEL APPLICATION OF CONTACT FRICTION FOR LATERALLY MOTION TUNABLE ACCELERATION-THRESHOLD SWITCH: MODELING AND SIMULATIONJ. C. Chiou and Y. J. LinJ. C. ChiouDepartment of Electrical and Control Engineering, National Chiao Tung University, Hsin-Chu, Taiwan, R. O. C. Search for more papers by this author and Y. J. LinDepartment of Electrical and Control Engineering, National Chiao Tung University, Hsin-Chu, Taiwan, R. O. C. Search for more papers by this author https://doi.org/10.1142/S1465876303001411Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractA novel tunable acceleration-thresholds switch device based on electrostatic force in controlling friction for desired acceleration-thresholds level is developed. Electrostatic forces based on desired friction are used to provide variable acceleration threshold level. The design concept is based on the fact that when acceleration is presented on the proofmass, an induced static friction will exactly cancel the effect of the acceleration. Upon the acceleration level is exceeding the maximum static friction, the proofmass engages movement in the acceleration direction and enter dynamic friction region. A contact pad is designed here to detect the on/off status of the accelerating proofmass. Dynamic simulation model, established by Matlab Simulink solver, indicated that the input signal is given with 10 triangular waves from 0.5g to 5g peak accelerations in 0.1sec duration, and the threshold switch gap is designed in 1 m. When VC, are equal to 1V, 1.5V, and 1.8V respectively, there are 8 signals (from 1.5g to 5g), 5 signals (from 3g to 5g), and 3 signals (from 4g to 5g) exceeded 1 m threshold switch gap which demonstrated the effectiveness of the present design concept. Experimental results of the tunable acceleration-thresholds switch device will be reported in the near future.Keywords:tunableacceleration-thresholdfrictiondynamic simulation References Jeung Sang Go, Young-Ho Cho, and Byung Man Kwak, Acceleration Microswitches With Adjustable Snapping Threshold, Transducers '95, (1995) 691 – 694 . Google Scholar A. Selvakumar, N. Yazdi, and K. Najafi, Low power, wide range threshold acceleration sensing system, MEMS '96, (1996) 186–191 . Google ScholarSven Michaeliset al., Sensors and Actuators A: Physical 85(1–3), 418 (2000). Crossref, Google ScholarK. Deng and W. H. Ko, Solid-State Sensor and Actuator Workshop, 1992, 5th Technical Digest (IEEE, 1992) pp. 98–101. Crossref, Google Scholar K. Deng, W. H. Ko, and G. M. Michal, A preliminary study on friction measurements in MEMS, Solid-State Sensors and Actuators, International Conference, (1991) 213–216 . Google Scholar FiguresReferencesRelatedDetails Recommended Vol. 04, No. 02 Metrics History Keywordstunableacceleration-thresholdfrictiondynamic simulationPDF download

Stable and Transportable Regional Magnitudes Based on Coda-Derived Moment-Rate Spectra

We describe an empirical calibration method for obtaining stable seismic source moment-rate spectra derived from regional coda envelopes using broadband stations. The results of applying this method yield source spectra that are more stable than any other direct-phase measure to date. The procedure accounts for all propagation, site, and S -to-coda transfer function effects. The resultant coda-derived moment-rate spectra are then used to provide traditional band-limited magnitudes (e.g., M L , m b ), as well as an unbiased, unsaturated magnitude (moment magnitude, M w ) that is tied to a physical measure of earthquake size (i.e., seismic moment). We validate our results by comparing our coda-derived moment estimates with those obtained from long-period waveform modeling. Most importantly, we demonstrate that the interstation magnitude scatter is significantly reduced when using long-window-length coda (i.e., M w (coda) and m b (coda)). However, when we use short-window coda measurements of 5 sec in length taken after twice the direct-wave travel time, the scatter remains large, comparable to direct waves. Once calibrated, the coda-derived source spectra provide stable, unbiased magnitude estimates for events that are too small either to be reliably waveform modeled or to be seen at far-regional and teleseismic distances. This property is ideal for sparse local or regional networks. We found that our source amplitude estimates were nearly insensitive to the expected source radiation pattern and exhibited roughly a factor of 3-5 less interstation scatter when compared against coda duration and conventional direct-phase measurements (e.g., P g , L g ). We also found that the coda stability, as measured by the interstation scatter for common events, reached a minimum value beyond a certain critical measurement window length. For example, at 6-8 Hz, the interstation standard deviation was less than 0.08 provided the coda measurement was at least ∼80 sec in duration, whereas at 1.5-2.0 Hz, the critical window length was ∼100 sec. For all frequency bands, as the coda window becomes shorter, the standard deviation increases, asymptotically approaching the direct-wave scatter. In this article we describe in detail the calibration methodology and address concerns related to choosing optimal measurement window lengths, estimating error, testing empirical path corrections, and tying coda amplitudes to an absolute scale. In order to demonstrate the usefulness and transportability of our method, we chose the Dead Sea Rift as our study area.

Brief communication: arboreal bipedalism in Bwindi chimpanzees.

Evidence of the form and function of bipedal behavior in nonhuman primates provides critical evidence to test theories about the origins of hominid bipedalism. Bipedalism has long been considered an evolutionarily interesting but rare behavior in wild chimpanzees. During May 2001, chimpanzees of the Ruhija community in the Bwindi Impenetrable National Park, Uganda, engaged in an exceptional frequency of arboreal bipedalism when feeding in large Ficus trees. Seventy-eight bipedal bouts of at least 5 sec duration were recorded for the entire community (0.49 bouts/hr), with a mean duration of 13.7 sec (+/-1.6 sec). The animals employed many variations on the bipedal postural theme, ranging from erect standing on the largest substrates while grasping overhead limbs for support, to standing on one leg while suspending the other leg in space, to extended-lean standing, in which bipedal standing transitioned into horizontal arm-leg suspension as the animal reached for more distant fruits. Bipedalism was used as part of a behavioral repertoire that integrated brachiation, four-limbed suspension, and forelimb-supported standing for effective small-fruit foraging. These observations suggest that under certain ecological conditions, arboreal bipedalism can be an important posture for wild chimpanzees, and may have been an important behavioral precursor to full terrestrial bipedalism.

Apnoeic response to stimulation of peripheral GABA receptors in rats.

Respiratory effects of intracarotid injection of gamma-amino-butyric acid (GABA) were investigated in two groups of rats. In the first group of 12 rats the effects of GABA were checked in the intact state, following bilateral vagotomy and GABA receptor blockade. The second group consisted of five initially vagotomized rats, challenged with GABA prior to and after bilateral carotid chemodenervation (CSN-cut). All rats were urethane and chloralose anaesthetized and spontaneously breathing. Injection of 39 micromol/kg GABA prior to and after vagotomy induced an expiratory apnoea of, respectively 5.5+/-0.84 sec and 3.9+/-0.6 sec duration (mean+/-S.E.M.), P>0.05 in all 12 rats. In breaths that followed the apnoea tidal volume increased above the control level by 23.3% (P<0.01) and 25.6% (P<0.01) pre- and post-vagotomy, respectively. Blockade of GABA receptors with bicuculline and picrotoxin abolished the inhibition of breathing. In five vagotomized rats with intact carotid sinus nerves (CSNs) intracarotid GABA challenge increased tidal volume by 39% compared with baseline breathing (P<0.05). Section of the CSNs precluded the occurrence of apnoea and undergoing respiratory changes evoked by GABA. Intracarotid GABA caused significant decrease in the mean blood pressure independent of the neural state, but the fall was delayed by CSNs neurotomy. Results of this study indicate that GABA given systemically induces apnoea followed by post-apnoeic hyperventilation. Carotid bodies are required for the ventilatory response to GABA; vagal afferents are not involved in this response.

Properties of a sodium channel (Na(x)) activated by strong depolarization of Xenopus oocytes.

Short (<1 sec) duration depolarization of Xenopus laevis oocytes to voltages greater than +40 mV activates a sodium-selective channel (Na(x)) with sodium permeability five to six times greater than the permeability of other monovalent cations examined, including K+, Rb+, Cs+, TMA+, and Choline+. The permeability to Li+ is about equal to that of Na+. This channel was present in all oocytes examined. The kinetics, voltage dependence and pharmacology of Na(x)distinguish it from TTX-sensitive or epithelial sodium channels. It is also different from the sodium channel of Xenopus oocytes activated by prolonged depolarization, which is more highly selective for Na+, requires prolonged depolarization to be activated, and is blocked by Li+. Intracellular Mg2+ reversibly inhibits Na(x), whereas extracellular Mg2+ does not have an inhibitory effect. Intracellular Mg2+ inhibition of Na(x), is voltage dependent, suggesting that Mg2+ binding occurs within the membrane field. Eosin is also a reversible voltage-dependent intracellular inhibitor of Na(x), suggesting that a P-type ATPase may mediate the current. An additional cytoplasmic factor is involved in maintaining Na(x) since the current runs down in internally perfused oocytes and excised membrane patches. The rundown is reversible by reintroduction of the membrane patch into oocyte cytoplasm. The cytoplasmic factor is not ATP, because ATP has no effect on Na(x) current magnitude in either cut-open or inside-out patch preparations. Extracellular Gd3+ is also an inhibitor of Na(x). Na(x) activation follows a sigmoid time course. Its half-maximal activation potential is +100 mV and the effective valence estimated from the steepness of conductance activation is 1.0. Na(x) deactivates monoexponentially upon return to the holding potential (-40 mV). The deactivation rate is voltage dependent, increasing at more negative membrane potentials.

PILOT STUDY

The purpose of this project was to determine the reliability of commonly used indices of anaerobic fatigue. Eight normal subjects (2 male, 6 female) with an average age of 38 ± 9.4 years participated in this study. Six trials of maximal elbow flexion were performed using a dynamometer with the elbow in 60° of flexion and the forearm in supination. The isometric fatigue test was 120 sec in duration and the isokinetic fatigue test featured 75 maximal repetitions (for 225 sec) at 180°/sec. Test-retest reliability was determined using intraclass correlation coefficients (ICC 3,1). Pearson correlations (r) were used to determine the relationship between muscle performance measures. Total impulse, total work, total impulse index (TII), MVC, and last third/first third impulse index (LFII) were very reliable (ICCs of 0.88 - 0.99). The total work index (TWI) and last third/first third work index (LFWI) displayed moderate to poor reliability with ICCs of 0.67 and 0.59 respectively. MVC was highly correlated with total impulse and total work (r = 0.95, p = 0.01), but not LFII (r = 0.24, p = 0.5), TWI (r = −0.54, p = 0.35) or TII (r = −0.32, p = 0.45). Rate of isokinetic and isometric fatigue had good correlation with total work (r = 0.78, p = 0.05) and impulse (r = 0.77, p = 0.05). LFII was poorly correlated with the TII (r = 0.11, p = 0.80). TII and LFII group mean values were 48.05% ± 5.8 (range 41–59%) and 48.97% ± 18.4 (range 14–71%) respectively. The data suggest that isometric tests may be more reliable than isokinetic tests in the assessment of anaerobic fatigue during maximal elbow flexion. Total work and impulse may represent anaerobic capacity based on their strong relationship with fatigue rate and MVC. TII and LFII have similar group mean values, but a weak relationship as they measure different components of fatigue. Force-time curve analysis reveals that TII may be a more general measure of fatigue, but less influenced by task strategy, than the LFII. LFII should not be used independent of TII.

Glucagon-Like Peptide-2 Stimulates Gut Mucosal Growth and Immune Response in Burned Rats

Major burn trauma often leads to reduced gut barrier function, immunosuppression, and increased bacterial translocation. We hypothesized that treatments that maintain normal gut after burn trauma will also reduce immunosuppression and bacterial translocation. Recent studies suggest that treatment with glucagon-like peptide-2 (GLP-2), which is synthesized in the intestine and released after food intake, elicits mucosal hyperplasia in the small intestine of rodents and prevents parenteral nutrition-induced gut hypoplasia. Therefore, we determined whether GLP-2 would prevent loss of gut integrity after major burn trauma. Osmotic minipumps were implanted into the peritoneum of 22 adult, male, Sprague-Dawley rats to infuse saline (10 microl/hr; n = 14) or GLP-2 (1 microg/hr; n = 8). On the next day 8 saline-infused and 8 GLP-2-infused rats were subjected to a 25 sec duration 30% BSA open flame burn, with the remaining rats serving as sham-burn controls. Five days after burn, all rats were killed. Gut protein was assessed, and immunosuppression was estimated by the mitogenic response of cultured splenocytes to phytohemagglutinin, pokeweed, and concanavalin A. Bacterial translocation was determined by culturing the mesenteric lymph nodes. Although protein content was significantly decreased in the ileum of burned rats treated with saline, the burned rats treated with GLP-2 exhibited significant increases in protein levels in duodenum, jejunum. and ileum. Colon protein was not affected by GLP-2 infusion. Saline-treated burned rats also exhibited immunosuppression, as suggested by significantly decreased responses to each of the mitogens. Infusion of GLP-2 normalized the response by the burned rats to each of the mitogens. Lymph nodes taken from sham rats exhibited no colony forming units, whereas in both of the burn groups, 50% of the cultures were positive. However, more aggressive colonization may have occurred in the saline-infused burned rats as compared with the GLP-2-infused burned rats (81 +/- 63 vs 3 +/- 2 colony forming units). These results suggest that GLP-2 may stimulate gut mucosa and reduce immunosuppression in burned rats. However, there does not seem to be a statistically significant positive effect of GLP-2 on bacterial translocation. Thus, improving small intestine mucosa may increase immunity while being ineffective against bacterial translocation.

THE IDENTIFICATION OF THE SYMPATHETIC NEURONS INNERVATING THE HAMSTER SUBMANDIBULAR GLAND AND THEIR ELECTROPHYSIOLOGICAL MEMBRANE PROPERTIES

The neuron innervating the hamster submandibular (SM) gland was identified in the superior cervical ganglion (SCG) in vitro by recording the antidromic response using the intracellular recording technique. After the cellular response was recorded, methylene blue was injected iontophoretically into the neuron from the recording electrode, and the location of the cell soma was determined. The salivatory neurons of the SM gland were in the small- to medium-sized group of the entire cell population of the SCG. The cell size was 36.3 x 24.4 microm (mean, n=45). The postganglionic fibers were entirely unmyelinated (mean: 0.34 m/sec at 28-30 degrees C, n=141). Eighty-seven percent of the cells were distributed in the central one-third of area between the external carotid nerve origin and the caudal pole in the SCG. The resting membrane potential, membrane input resistance, membrane time constant and membrane input capacitance of the salivatory neuron were as follows: -49.2+/-7.6 mV (n=102), 52.9+/-23.6 Mohms (n=71), 8.0+/-3.4 msec (n=71) and 147+/-50 pF (n=71). Fast- and slow-excitatory postsynaptic potentials (EPSPs) were evoked, but not slow-inhibitory postsynaptic potentials (IPSPs). The fast EPSP was 13.1+/-5.7 mV in amplitude and 46.2+/-17.1 msec in duration (n=35). The slow EPSP (20 Hz, 5 sec) was 6.9+/-11 .9 mV in amplitude and 101+/-43 sec in duration (n=16). The directly-evoked spike was 63.0+/-11.9 mV in amplitude and 5.9+/-1.3 msec in duration (n=54). The spike after-hyperpolarization (AHP) was 12.5+/-3.5 mV in amplitude and 353+/-161 msec in duration. Na+ and Ca+ channels were involved in the spike generation. The voltage-dependent K+ channels (delayed rectifier), A channels and rapidly Ca2+-activated K+ channels (BK channels) regulated the spike-falling phase. The delayed rectifiers, A channels, and BK and SK (slowly Ca2+-activated) channels were involved in generation of spike-AHP. Muscarine suppressed the Ca2+ component of spike via muscarinic receptors.

Wave-like variations and sudden density decreases in the lower thermosphere as measured by the San Marco V satellite

Neutral density measurements were carried out by the microaccelerometer on board the Italian San Marco V satellite in 1988. During the final week of its existence the satellite's perigee decreased to as low as 130 km. Measured density values were compared to the corresponding CIRA '86 (MSIS '86) or to our dMSIS model values. The residuals reveal a wavy structure of different time scales. Characterising the wave amplitude by the average deviation of the residuals, its dependence on different parameters was studied. These investigations demonstrated that the wave-amplitude varies with height, local solar time and geomagnetic disturbance level. There is a particularly developed wave pattern in the average deviations below 200 km. Case studies indicated that there are sudden density decreases of 20–30 sec duration that might be in connection with plasma bubble crossings by the satellite. Altogether 261 such cases were identified and their distribution as a function of height, LST and longitude have been investigated.

Effects of emitted Qi on in vitro natural killer cell cytotoxic activity.

The present study investigated the effects of Korean Qi-therapy, ChunSoo Energy Healing, on natural killer (NK) cell cytotoxicity in vitro depending on Qi-treatment time and the types of cells treated. NK cell cytotoxicity was assayed by measuring LDH release from tumor target cells (K562 cell lines). NK activity was significantly increased by emitted-Qi treatment of 30 sec duration. Three and 5 minutes of Qi projection created the greatest increase in NK cell activity when mixtures of NK cells and K562 cells were treated (1.81 and 2.12 fold for 4 hr culture; 1.54 and 1.36 for 16 hr culture, respectively). NK cell activity increased significantly in Qi-treated K562 cells alone (1.13 fold, p<0.05) compared to control. These results are consistent with in vivo Qi-therapy on humans and suggests that emitted-Qi has an acute stimulatory effect on NK cell activity. This study provides direct scientific support that Qi as such may positively affect human cellular immunity.

Vapreotide, a long-acting somatostatin analogue, dose-dependently inhibits exocrine pancreatic secretion in healthy volunteers

AUCover basal, mean ± SEM, ' p,;O.05VS. placebo (ANOVA followed byMann·Whitney test) mean age 6 (range 1.5 13 years). All underwent endoscopy for clinically indicated problems unrelated to the pyloric area. We placed under endoscopy a 6 fr. impedance catheter with 12 impedance sensors Icm apart (5 antral sensors, 2 pyloric sensors, and 5 duodenal sensors). We recorded BTE for 25 minutes following recovery from endoscopy in each patient. When fully awake, subjects drank water or apple juice. We found pyloric BTEs during II % of fasting recording time and 55% of recording time in the 10 minute following the drink. We analyzed 5 types of BTEs: propagating, retrograde, simultaneous, isolated, and complex. Propagating BTEs consisted of gas andlor fluid movement from antrum through pylorus, pylorus through duodenum, or a combination of the two. Propagating BTEs accounted for 48% of pyloric BTEs. Propagating BTEs averaged20 sec in duration. Retrograde BTEs consisting of fluid moving from duodenum to pylorus, pylorus to antrum, or a combination, accounted for 22% of pyloric BTEs. Retrograde BTEs averaged 10 sec in duration. Simultaneous BTEs consisted of distension in all areas at the same time, accounted for 19% of pyloric BTEs, and averaged 5 sec in duration. Isolated BTEs consisted of movement in the pylorus only and accounted for 5% of BTEs. Isolated BTEs were rhythmic, with clusters of l2/min, 3/min or 12 and 3/min waveforms superimposed. Complex BTEs were multidirectional, and accounted for 6% of all BTEs. We conclude that the patternsof pyloric BTEs are variable. Multichannel intraluminal impedance helps to assess pyloric physiology by determining pyloric bolus direction, duration and composition (gas or fluid). Impedanceshows promise as a method to assess pyloric function in health and in disease.

Activity-Dependent Regulation of Potassium Currents in an Identified Neuron of the Stomatogastric Ganglion of the CrabCancer borealis

Identified neurons of the stomatogastric ganglion of the crab Cancer borealis were voltage-clamped, and the current densities of three K+ currents were measured. The current densities of each of the three K+ currents varied twofold to fivefold in inferior cardiac (IC) neurons from different animals. Conventionally, this degree of variability has been attributed to experimental artifacts. Instead, we suggest that it reflects a natural variability that may be related to an underlying process of plasticity. First, we found that there is no fixed ratio among the three K+ currents. Second, we found that several hours of stimulation with depolarizing current pulses (0.5 sec duration at 1 Hz) altered the current density of the Ca2+-dependent outward current, IK(Ca), and the transient outward current, IA. This stimulation paradigm mimics the normal pattern of activity for these neurons. The effect of stimulation on the IA current density was eliminated when Ca2+ influx was blocked by extracellular Cd2+. In contrast, the K+ current densities of the lateral pyloric (LP) neuron were unaffected by the same pattern of stimulation, and the currents expressed by both the IC and the LP neurons were insensitive to hyperpolarizing pulses at the same frequency. We conclude that the conductance densities expressed by neurons may vary continually depending on the recent history of electrical activity in the preparation, and that intracellular Ca2+ may play a role in the processes by which activity influences the regulation of current densities in neurons.

Rapid imaging of hyperpolarized gas using EPI.

Rapid repetitive MRI of hyperpolarized (HP) gases using echo-planar imaging (EPI) has been theoretically investigated and experimentally demonstrated for (3)He in human lung. A quantitative treatment of signal attenuation and magnetization consumption for the unique circumstance of a rapidly diffusing nonrenewable magnetization source has been performed. Rapid (compared to the human respiratory cycle) and repetitive imaging of the lung gas space with EPI and a single delivered bolus of HP-(3)He is feasible using low flip angles, provided the voxels are not too small. A coarse-grid (32 x 64) EPI pulse sequence has been developed and implemented to image the lungs of healthy volunteers during rebreathing of a HP-(3)He/N(2) gas mixture. A set of three 10-mm axial slices was imaged every 0.12 sec for the 36 sec duration of rebreathing, yielding a real-time visualization of ventilation. Despite some mild artifacts, the images are of good quality and show changes in gas density related to respiratory physiology. Magn Reson Med 42:507-514, 1999.

System identification of atrial activation during chronic atrial fibrillation in man

To clarify the mechanisms maintaining chronic atrial fibrillation (CAF), a method for system identification of activation patterns of the atria during sinus rhythm (SR), artificial atrial pacing and atrial fibrillation, was developed. Data were obtained as repeated recordings of 8 sec in duration, each of 56 atrial bipolar electrograms, simultaneously acquired during open-heart surgery at multiple sites in the right atrial-free wall in 12 patients with stable SR and during artificial pacing and 16 patients with CAF. The realization theory was applied to fit the multivariate electrograms corresponding to individual beats during SR and type-I activations during AF, respectively. It was concluded that the local electrogram is a predictable signal during SR, artificial pacing, as well as during type-I atrial activation, and the proposed method may be used for further investigations concerning the deterministic and predictive nature of atrial activation during atrial fibrillation.