Extra Stimulus Research Articles

Automaticity: Componential, Causal, and Mechanistic Explanations.

The review first discusses componential explanations of automaticity, which specify non/automaticity features (e.g., un/controlled, un/conscious, non/efficient, fast/slow) and their interrelations. Reframing these features as factors that influence processes (e.g., goals, attention, and time) broadens the range of factors that can be considered (e.g., adding stimulus intensity and representational quality). The evidence reviewed challenges the view of a perfect coherence among goals, attention, and consciousness, and supports the alternative view that (a) these and other factors influence the quality of representations in an additive way (e.g., little time can be compensated by extra attention or extra stimulus intensity) and that (b) a first threshold of this quality is required for unconscious processing and a second threshold for conscious processing. The review closes with a discussion of causal explanations of automaticity, which specify factors involved in automatization such as repetition and complexity, and a discussion of mechanistic explanations, which specify the low-level processes underlying automatization.

Acetylcholine Suppresses Ventricular Arrhythmias and Improves Conduction and Connexin-43 Properties During Myocardial Ischemia in Isolated Rabbit Hearts.

Acetylcholine (ACh), a vagal efferent neurotransmitter, markedly improves survival in rats with myocardial ischemia (MI) by preventing ischemic loss of gap junction (Gj) and by inducing anti-apoptotic cascades. However, electrophysiological mechanisms of the antiarrhythmic effect of ACh after acute MI are still unclear. Acute MI was induced by ligation of the left anterior descending (LAD) coronary artery in Langendorff-perfused rabbit hearts with (ACh(+):n = 11) or without (ACh(-):n = 12) 10 μmol/L ACh delivered continuously starting at 5 minutes before LAD ligation. Action potentials on the left ventricular (LV) anterior surface (≈2×2 cm) were recorded by optical mapping during pacing from the LV epicardium (BCL = 500 milliseconds). Conduction velocities (CVs) at 256 sites were calculated and the ventricular tachycardia/ventricular fibrillation (VT/VF) susceptibility was also assessed by programmed electrical stimulation before and 30 minutes after MI. The amount and distribution of Gj protein connexin-43 was analyzed by immunoblotting and immunohistochemistry. Averaged CV in the ischemic border zone (IBZ) was significantly slower in ACh(-) than in ACh(+) (21 ± 7 vs. 34 ± 6 cm/s; P < 0.01). Short-coupled extra stimulus further decreased CV of IBZ in ACh(-) (13 ± 4 cm/s) but did not change that in ACh(+) (34 ± 5 cm/s), leading to a high incidence of conduction block in IBZ in ACh(-) but not in ACh(+) (83% vs. 0%). VT/VF after MI were induced in ACh(-) but suppressed in ACh(+) (10/12 vs. 3/11; P < 0.01). Connexin-43 in the LV anterior wall was significantly reduced after MI in ACh(-) but not in ACh(+). ACh may suppress VT/VF by preventing loss of Gj and improving CV in IBZ during acute MI.

Neuromuscular and athletic performance following core strength training in elite youth soccer: Role of instability.

Cross-sectional studies revealed that inclusion of unstable elements in core-strengthening exercises produced increases in trunk muscle activity and thus potential extra stimuli to induce more pronounced performance enhancements in youth athletes. Thus, the purpose of the study was to investigate changes in neuromuscular and athletic performance following core strength training performed on unstable (CSTU) compared with stable surfaces (CSTS) in youth soccer players. Thirty-nine male elite soccer players (age: 17 ± 1 years) were assigned to two groups performing a progressive core strength-training program for 9 weeks (2-3 times/week) in addition to regular in-season soccer training. CSTS group conducted core exercises on stable (i.e., floor, bench) and CSTU group on unstable (e.g., Thera-Band® Stability Trainer, Togu© Swiss ball) surfaces. Measurements included tests for assessing trunk muscle strength/activation, countermovement jump height, sprint time, agility time, and kicking performance. Statistical analysis revealed significant main effects of test (pre vs post) for trunk extensor strength (5%, P < 0.05, d = 0.86), 10-20-m sprint time (3%, P < 0.05, d = 2.56), and kicking performance (1%, P < 0.01, d = 1.28). No significant Group × test interactions were observed for any variable. In conclusion, trunk muscle strength, sprint, and kicking performance improved following CSTU and CSTS when conducted in combination with regular soccer training.

Effects of core strength training using stable versus unstable surfaces on physical fitness in adolescents: a randomized controlled trial.

BackgroundIt has been demonstrated that core strength training is an effective means to enhance trunk muscle strength (TMS) and proxies of physical fitness in youth. Of note, cross-sectional studies revealed that the inclusion of unstable elements in core strengthening exercises produced increases in trunk muscle activity and thus provide potential extra training stimuli for performance enhancement. Thus, utilizing unstable surfaces during core strength training may even produce larger performance gains. However, the effects of core strength training using unstable surfaces are unresolved in youth. This randomized controlled study specifically investigated the effects of core strength training performed on stable surfaces (CSTS) compared to unstable surfaces (CSTU) on physical fitness in school-aged children.MethodsTwenty-seven (14 girls, 13 boys) healthy subjects (mean age: 14 ± 1 years, age range: 13–15 years) were randomly assigned to a CSTS (n = 13) or a CSTU (n = 14) group. Both training programs lasted 6 weeks (2 sessions/week) and included frontal, dorsal, and lateral core exercises. During CSTU, these exercises were conducted on unstable surfaces (e.g., TOGU© DYNAIR CUSSIONS, THERA-BAND© STABILITY TRAINER).ResultsSignificant main effects of Time (pre vs. post) were observed for the TMS tests (8-22%, f = 0.47-0.76), the jumping sideways test (4-5%, f = 1.07), and the Y balance test (2-3%, f = 0.46-0.49). Trends towards significance were found for the standing long jump test (1-3%, f = 0.39) and the stand-and-reach test (0-2%, f = 0.39). We could not detect any significant main effects of Group. Significant Time x Group interactions were detected for the stand-and-reach test in favour of the CSTU group (2%, f = 0.54).ConclusionsCore strength training resulted in significant increases in proxies of physical fitness in adolescents. However, CSTU as compared to CSTS had only limited additional effects (i.e., stand-and-reach test). Consequently, if the goal of training is to enhance physical fitness, then CSTU has limited advantages over CSTS.Trial registrationClinicalTrials.gov Identifier: NCT02290457 Registered 13 November 2014.

The possibilities of using elastic therapeutic (Kinesio) tape in patients with scoliosis

Elastic Therapeutic (Kinesio Tape) has rapidly become a recognised therapeutic modality in many musculoskeletal and neurological disorders. This tape, applied with a certain amount of stretch to its own paper backing is known under many names making research into it a challenging task. Its recoil properties make it a very suitable tool to assist in current scoliosis management. The studies of the various elastic therapeutic tape brands have reported positive effects on pain, ROM, balance, strength, function and proprioception. A large amount of anecdotal evidence has been published and warrants further research. It is reasonable to assume that the outcome of the research on the effects of taping on both upper and lower extremities by means of Functional Magnetic Resonance Imaging and Ultrasonic Imaging is transferable to the trunk. Both the research on the physiological movement of the skin of the trunk captured by three-dimensional motion analysis system (Vicon Motion Systems) by T. Fukui and the videos of the skins’ anatomy and physiology by Dr. J.C. Guimberteau have resulted in novel ways to use the tape. A number of these tape possibilities will be presented and their function addressed. The use of elastic therapeutic tape applications to: - assist patients to 'hold' their corrected posture (Schroth, SEAS exercises). In both Idiopathic Adolescent Scoliosis and adult scoliosis patients this extra stimulus gives 24hours a day sensory information. - help relieve pain in the (elderly) scoliosis patient with postural collapse. - assist pulmonary function in the both patients with Idiopathic Adolescent Scoliosis and neuromuscular scoliosis will all be presented and discussed. Elastic Therapeutic Tape is a wonderful new extra tool in the management of scoliosis patients.

Acute Atrial Stretch Results in Conduction Slowing and Complex Signals at the Pulmonary Vein to Left Atrial Junction

Background— The pulmonary vein–left atrial (PV–LA) junction is key in pathogenesis of AF, and acute stretch is an important stimulus to AF. We aimed to characterize the response of the junction to acute stretch, hypothesizing that stretch would result in electrophysiological changes predisposing to re-entry. Methods and Results— Fifteen participants undergoing cardiac surgery underwent evaluation of the right superior PV–LA junction using an epicardial mapping plaque. In 10, this was performed before and after atrial stretch imposed by rapid volume expansion, and in 5, it was performed with an intervening observation period. Activation was characterized by conduction slowing and electrogram fractionation transversely across the PV–LA junction, with lines of block also demonstrated perpendicular to the junction. Conduction was decremental (plaque activation time 135.8±46.8 ms with programmed extra stimuli at 10 ms above effective refractory period versus 66.1±22.9 ms with pacing at 400 ms; P &lt;0.001) and percentage fractionation was greater with programmed extra stimuli at 10 ms above (33.5%±15.3% versus 20.7%±14.0%, P =0.001). Right atrial pressure increased by 2.5±1.8 mm Hg ( P =0.002) with volume expansion. Stretch resulted in conduction slowing across the PV–LA junction (increase in activation time 10.9±14.6 ms in acute stretch group versus −0.1±4.5 ms in control group; P =0.002). Conduction slowing was more marked with programmed extra stimuli at 10 ms above effective refractory period than with stable pacing (13.4±16.5 ms versus 1.7±5.4 ms; P =0.003). Stretch resulted in a significant increase in fractionated electrograms (7.9%±7.0% versus −0.4±3.3; P =0.004). Conclusions— Acute stretch results in conduction slowing across the PV–LA junction, with a greater degree of signal complexity. This substrate may be important in AF initiation and maintenance by promoting re-entry.

Photo- and Electro- Switchable Hybrid Assembly of Redox-Active Polyoxometalates and Block Copolymers

The hybrid assembled materials based on redox-active polyoxometalates H3PMo12O40·nH2O and the neutral–cationic block copolymers poly(ethylene oxide-block-N,N-dimethylaminoethyl methacrylate) in aqueous solution were constructed through electrostatic interactions. Triggered by photochemical or electrochemical methods, the charge number of the redox-active polyoxometalates charged in situ, which not only induced the chromisity of the solution, but also driven diverse morphologies of the assembly. The assembly morphologies could be switched between spherical micelles and wormlike micelles after extra stimuli. Both of chromic and assembling processes are reversible and repeatable. Moreover, the hybrid materials improve the processability of the inorganic cluster polyoxometalates which maintains its original chromic properties at the same time. This simple strategy put a general way to fabricate smart stimuli-responsive polyoxometalates-based functional materials with potential applications in optical switches, biosensors, detectors and electrochromic devices. The variety of the ionic inorganic clusters and polyelectrolytes offered a broaden platform to enrich the electrostatic-motivated assembling and expand their applications.

Yoğun Bakım Hastalarında Duyusal Girdi Sorunları ve Hemşirelik Yaklaşımı

Intensive care units are special units that differ from other units of the hospital in terms of its treatment methods, technical equipment, physical appearance and sensory environment. Intensive care units that the advanced technological developments used in set the stage for appearing of sensory changing such as sensory deprivation and sensory pressure for patients by the reasons such as difference and intensity of the treatment, extra environmental stimulus, and lack of social support systems as well as being lifesaving. That’s why, while meeting the care and treatment requirements of intensive care patients, a holistic nursing care in which the patients’ psychosocial requirements are not ignored as well as their physical requirements is meaningful and important. In this article, writers aim to attract attention to the sensory input problems that the intensive care patients experienced and to explain nursing approaches that can be served in this direction.

Feasibility and efficacy of a remote real-time wireless ECG monitoring and stimulation system for management of ventricular arrhythmia in rabbits with myocardial infarction.

The purpose of this study was to explore the feasibility of continuous remote monitoring, and the induction and termination of malignant ventricular arrhythmias (VAs) by a novel implantable electronic cardiovascular device (IECD) system in rabbits with myocardial infarction (MI). The IECD was implanted and MI was induced by ligation of the left anterior descending coronary artery in 20 adult rabbits. Internet-based remote electrocardiogram (ECG) monitoring and ventricular stimulation were conducted in remote locations with internet access. The voltage amplitudes of the stimulation signals were recorded synchronously by remote and surface ECG. Programmed stimulation with regular stimuli and regular stimuli with an added extra stimulus were performed prior to and following the MI surgery to induce and terminate VAs. IECD implantation and MI surgery, as well as qualified remote and bidirectional signal communications between the implanted IECD and extracorporeal system, were successfully achieved in 18 rabbits. The voltage of the stimulation signals recorded by the remote and surface ECGs showed a good correlation with the stimulation current (remote ECG, r=0.972 and surface ECG, r=0.988; P<0.001). Sustained ventricular tachycardia (VT) was induced in five rabbits (5/20, 25%) prior to MI induction and in 12 rabbits (12/16, 75%) following MI induction. Of the 17 induced VTs, 16 were successfully terminated by remote ventricular stimulation. The novel IECD system provides qualified remote wireless ECG monitoring and possesses the potential to induce and terminate VAs by remote ventricular pacing in this rabbit model of MI. Thus, this model of MI may be used to test the efficacy of novel drugs and devices for the management of VAs.

Direct reprogramming based on transcriptional regulatory network analysis

Trans-differentiation of cells through direct reprogramming offers significant potential for regenerative medicine and drug screen, but currently it requires exhaustive trials and errors before the desired target cells can be created. Based on the comprehensive transcriptome analyses by the FANTOM consortium, in particular the recently published transcriptional regulatory network analysis, we have developed a systematic method for direct reprogramming and succeeded in creating monocyte-like cells with several monocyte-specific functions. Further analysis of the created cells reveals that the transcriptional regulatory networks and the epigenomes of the original terminally differentiated cells act as strong barriers that prevent easy reprogramming by extra stimuli. These biological insights should be carefully considered for efficient and complete direct reprogramming.

Seeing the unseen: Autism involves reduced susceptibility to inattentional blindness.

Attention research in individuals with autism spectrum disorder (ASD) has produced conflicting results. Some findings demonstrate greater distractibility while others suggest superior focused attention. Applying Lavie's load theory of attention to account for this discrepancy led us to hypothesize increased perceptual capacity in ASD. Preliminary support for our hypothesis has so far been found for adults with ASD with reaction time (RT) and signal detection sensitivity measures. Here we test the novel prediction we derived from this hypothesis that children with ASD should have lower rates of inattentional blindness than controls. Twenty-four children with ASD (mean age = 10 years 10 months) and 39 typically developing children (age and IQ matched) took part in the study. We assessed the effects of perceptual load on the rates of inattentional blindness in each group. Participants performing a line discrimination task in either a high load or low load condition were presented with an unexpected extra stimulus on a critical trial. Performance on the line judgment task and rates of detection and stimulus identification were recorded. Overall rates of detection and identification were higher in the ASD group than in the controls. Moreover, whereas both detection and identification rates were significantly lower in the high (compared with low) load conditions for the controls, these were unaffected by load in the ASD group. Reduced inattentional blindness rates under load in ASD suggests higher perceptual capacity is a core feature, present from childhood and leading to superior performance in various measures of perception and attention.

11 Arrhythmogenic Right Ventricular Cardiomyopathy-Like Phenotype Induced by Endurance Training and Prevented by Preload Reduction in Heterozygeous Desmoglein-2 Mutants

Arrhythmogenic right ventricular cardiomyopathy (ARVC) significantly contributes to sudden cardiac death in young otherwise healthy patients, especially endurance athletes. 5–10% of patients with ARVC harbour mutations in the extracellular domains of the desmoglein (DSG) 2 gene. To assess the role of DSG2 in ARVC pathomechanism, mice lacking exons 4–6 of the endogenous DSG2 gene (DSG2mt) were generated. Homozygous DSG2mt/mice developed dilatation of ventricles and pronounced fibrosis. Heterozygous DSG2mt/wt mutants did not show such morphological alterations. Methods To study whether exercise provokes a cardiac phenotype in DGSwt/mt mice, they were subjected to endurance training and compared with wild-type (WT) littermates. We also studied if preload reduction can prevent right ventricular dilation with training by concomitant therapy with nitrates and diuretics. Echocardiography was performed with 2% isoflurane + oxygen, using a small animal ultrasound unit. Right ventricular (RV) dimensions were increased in DSG2wt/mt after training compared to pre-training and compared to WT after training. Electrophysiological studies in isolated Langendorff DSGwt/mt and WT hearts from mice terminally anaesthetised with urethane (2 mg/kg) showed a correlation of the DSG2 mutation with increased arrhythmia inducibility after endurance training. Ventricular arrhythmias were induced by a single extra stimulus during right ventricular stimulation in 5 of 8 DSG2wt/mt, but in none of the 7 WT hearts (p = 0.03). Preload reduction prevented excessive right ventricular enlargement with endurance training in DSG2wt/mt. In conclusion, endurance training revealed an ARVC-like phenotype in heterozygous desmoglein mutant mice. Right ventricular dilation could be prevented by preload-reducing therapy.

A Simplified Approach for Simultaneous Measurements of Wavefront Velocity and Curvature in the Heart Using Activation Times

The velocity and curvature of a wave front are important factors governing the propagation of electrical activity through cardiac tissue, particularly during heart arrhythmias of clinical importance such as fibrillation. Presently, no simple computational model exists to determine these values simultaneously. The proposed model uses the arrival times at four or five sites to determine the wave front speed (v), direction (θ), and radius of curvature (ROC) (r0). If the arrival times are measured, then v, θ, and r0 can be found from differences in arrival times and the distance between these sites. During isotropic conduction, we found good correlation between measured values of the ROC r0 and the distance from the unipolar stimulus (r = 0.9043 and p < 0.0001). The conduction velocity (m/s) was correlated (r = 0.998, p < 0.0001) using our method (mean = 0.2403, SD = 0.0533) and an empirical method (mean = 0.2352, SD = 0.0560). The model was applied to a condition of anisotropy and a complex case of reentry with a high voltage extra stimulus. Again, results show good correlation between our simplified approach and established methods for multiple wavefront morphologies. In conclusion, insignificant measurement errors were observed between this simplified approach and an approach that was more computationally demanding. Accuracy was maintained when the requirement that ε (ε = b/r0, ratio of recording site spacing over wave fronts ROC) was between 0.001 and 0.5. The present simplified model can be applied to a variety of clinical conditions to predict behavior of planar, elliptical, and reentrant wave fronts. It may be used to study the genesis and propagation of rotors in human arrhythmias and could lead to rotor mapping using low density endocardial recording electrodes.

Intrinsic left atrial histoanatomy as the basis for reentrant excitation causing atrial fibrillation/flutter in rats

Although the pulmonary veins are accepted as preferential trigger sites for paroxysmal atrial fibrillation/flutter (AF/AFL), the intrinsic basis for reentrant excitation is undetermined in persistent AF/AFL. To identify histoanatomic substrates for reentrant AF/AFL in rats. Spatiotemporal patterns of impulse propagation were visualized optically on the posterior surface of the atria in di-4-ANEPPS-stained Langendorff-perfused rat heart/lung preparations. The relevant histology was also analyzed. Burst (S1-S2) pacing at the right atrium provoked AF/AFL in 15 of 19 hearts, and most cases developed by organized reentrant excitation through the coronary sinus (CS) and left atrial (LA) roof, with nonorganized irregular propagation in 3 cases. The reentrant circuit developed along 2 pathways of propagation: a slower pathway at the LA roof (conduction velocity, 42.4 ± 16.6 cm/s) and a faster pathway along the CS (conduction velocity, 53.3 ± 9.2 cm/s). Upon extra stimulus (S2) after consecutive S1 pacing, the impulse at the roof propagated retrogradely from the CS, resulting in reentrant propagation anchored by the atrial septum and posterior LA. Histologic quantification revealed significantly lower myocardial density in the posterior LA and the septum than elsewhere in the atria. Moreover, myocytes in the LA roof, than in the CS, were of lower density, more randomly arranged in the direction of conduction, and characterized by more disorganized distribution of connexin 43 over the entire cell membrane, which is consistent with the slower impulse propagation there. The intrinsic histoanatomic heterogeneity in the LA would constitute a pro-reentrant substrate responsible for perpetuating AF/AFL.

Role of SA–VA interval after resetting of the tachycardia by ventricular extra stimulus in differentiating AVNRT and OAVRT regarding sensitivity and specificity, single center study

Abstract Introduction Right ventricular entrainment represents a useful tool for differentiating atrioventricular nodal re-entrant tachycardia (AVNRT) from orthodromic re-entrant tachycardia (ORT) using an accessory pathway. However, inability to entrain PSVT by pacing can be observed in some patients. Aim of study Assessing whether the resetting response to SVT by single or double right ventricular extra-stimuli is a useful maneuver to differentiate AVNRT from OAVRT by calculating the difference between the stimulus-atrial interval during resetting of SVT and the VA interval during SVT (SA–VA). Methods Electrophysiological study was conducted with a calculation of the SA–VA interval after resetting of the tachycardia by ventricular extra stimulus and differential entrainment from RV apex and base, then comparing the two methods regarding sensitivity and specificity in differentiating AVNRT from OAVRT conducted on 25 patients. Results Measuring the SA–VA interval after resetting of the tachycardia by an extra stimulus during the His refractoriness during the tachycardia showed in AVNRT a mean of 145.76 ± 31.53 and in OAVRT a mean ± SD of 91.52 ± 12.79 with a high statistical significance, with a cutoff point of 107 ms above which the SVT is expected to be AVNRT, and below which OAVRT. Using this technique could differentiate AVNRT from OAVRT with an overall sensitivity of 100% and specificity of 76.47%, in comparison to a specificity of 81.8% when using the technique of differential entrainment from RV apex and base. Conclusion Resetting of SVT by ventricular extra-stimuli is a useful maneuver for differentiating AVNRT from ORT and is applicable even when entrainment is impossible.

Myofilament calcium de-sensitization and contractile uncoupling prevent pause-triggered ventricular tachycardia in mouse hearts with chronic myocardial infarction

Myocardial infarction (MI) is a major risk for ventricular arrhythmia. Pause-triggered ventricular arrhythmia can be caused by increased myofilament Ca binding due to sarcomeric mutations or Ca-sensitizing compounds. Myofilament Ca sensitivity is also increased after MI. Here we hypothesize that MI increases risk for pause-triggered ventricular arrhythmias, which can be prevented by myofilament Ca-desensitization and contractile uncoupling. To test this hypothesis, we generated a murine chronic MI model using male B6SJLF1/J mice (n=40) that underwent permanent ligation of the left anterior descending coronary artery. 4weeks post MI, cardiac structure, function and myofilament Ca sensitivity were evaluated. Pause-dependent arrhythmia susceptibility was quantified in isolated hearts with pacing trains of increasing frequency, followed by a pause and an extra stimulus. Coronary ligation resulted in a mean infarct size of 39.6±5.7% LV and fractional shortening on echocardiography was reduced by 40% compared to non-infarcted controls. Myofilament Ca sensitivity was significantly increased in post MI hearts (pCa50: Control=5.66±0.03; MI=5.84±0.05; P<0.01). Exposure to the Ca desensitizer/contractile uncoupler blebbistatin (BLEB, 3μM) reduced myofilament Ca sensitivity of MI hearts to that of control hearts and selectively reduced the frequency of post-pause ectopic beats (MI 0.12±0.04 vs MI+BLEB 0.01±0.005 PVC/pause; P=0.02). BLEB also reduced the incidence of ventricular tachycardia in chronic MI hearts from 59% to 10% (P<0.05). We conclude that chronic MI hearts exhibit increased myofilament Ca sensitivity and pause-triggered ventricular arrhythmias, which can be prevented by blebbistatin. Decreasing myofilament Ca sensitivity may be a strategy to reduce arrhythmia burden after MI.

Myofilament Calcium Sensitization Causes Pause-Dependent Ventricular Ectopy in Mouse Hearts with Acute and Chronic Myocardial Infarction

Background. Increased myofilament Ca2+ sensitivity has been associated with cardiac arrhythmias in several cardiomyopathies. During the course of myocardial infarction (MI), myofilament Ca2+ sensitivity is reduced during acute ischemia but increases in the chronic stage. Thus, we aimed to compare the arrhythmogenic patterns during an acute MI or after chronic MI in mice.Methods. In theacute MI group, isolated hearts were investigated 15 min after left anterior descending (LAD) coronary artery ligation. In the chronic MI group, hearts were harvested 4 weeks after LAD ligation. To measure arrhythmia susceptibility, isolated hearts from both groups underwent a ventricular pacing challenge consisting of pacing trains of increasing frequency, followed by a pause and an extra stimulus, in the presence or in the absence of the Ca2+ sensitizer EMD 57033 (3 µM) or the Ca2+ de-sensitizer and contractile uncoupler Blebbistatin (3 µM).Results. Acute MI caused frequent ventricular ectopyduring the steady-state pacing, but not after a pause. Acute MI hearts became susceptible to post-pause ectopy only after Ca2+ sensitization with EMD. In contrast, chronic MI hearts exhibited only very modest ventricular ectopy during the pacing trains (33.3%, p<0.01 vs acute MI), but consistently exhibited ectopy after a pause (91.6%), which was prevented by Ca2+ de-sensitization with blebbistatin (10%, p<0.05). Compared to acute MI, the incidence of ventricular tachycardia (VT) was significantly increased in chronic MI, which could be prevented by blebbistatin (MI: 70%, MI+Bleb: 10%, p<0.05, n=10 per group).Conclusion. Different patterns of arrhythmia induction are involved in acute and chronic MI hearts. Our data suggest that increased myofilament Ca2+ sensitivity strongly promotes ventricular ectopy and VT's after a pause, but does not affect ectopy during regular pacing.

Talking to the Converted or Reaching Out to the Uncommitted? Who Do Political Campaigns Influence?

Research on campaign effects in British elections has repeatedly shown the importance of constituency campaigning. Other things being equal, the more parties campaign locally, the more votes they gain and the fewer votes go to their rivals. However, implicit in the literature is the assumption that campaigns affect all voters in the same way. There are good theoretical reasons for doubting this. For instance, we might expect that strong partisans will be less likely to change their vote decisions consequent to exposure to a party's campaign than weaker partisans and nonaligned voters. Similarly, political campaigns are likely to have a larger impact on those relatively uninterested in politics than on the more interested, since the former may need the extra information and stimulus offered by the campaign to make up their minds. The paper employs campaign panel data from the 2005 British Election Study to evaluate these and other claims. Who is most, and who is least, open to influence by parties’ campaign efforts?

Exogenous induction of ovarian activity and ovulation and transfer of fresh embryos of domestic cat (Felis catus)

The objective of the present study was the exogenous stimulation of ovarian activity and definition of embryo collection, and transfer protocols, in the domestic cat for potential application in non-domestic endangered species. Sixteen adult queens and two adult male reproducers kept in the experimental cat house at the Morphology sector at the Veterinary Department (DVT), UFV, were used in this study. All the queens received a single application of 150 IU Equine Chorionic Gonadotropin (eCG) in the post estrus to induce ovarian activity and 80 to 84 hours later, received a single application of 100 UI Human Chorionic Gonadotropin (hCG) to induce ovulation. After hCG application, only the donor queens were naturally mated. The receptor queens received extra stimulus for induction of ovulation through manipulation of an intravaginal swab. Five to six days after hCG application, the donor queens were subjected to a laparotomy for embryo collection that was performed by trans-horn uterine washing. On average, six embryos were surgically inovulated. They were classified as type I and III compact morula and blastocysts in four receptor queens. Three animals presented pregnancy confirmed by ultrasound at day 36 and two of these animals gave birth to litters of two and four offsprings, respectively, at 66 and 63 days after induction of ovulation. Except for one still birth, all the offspring developed normally.

Evolutionary crossroads in developmental biology: annelids

Annelids (the segmented worms) have a long history in studies of animal developmental biology, particularly with regards to their cleavage patterns during early development and their neurobiology. With the relatively recent reorganisation of the phylogeny of the animal kingdom, and the distinction of the super-phyla Ecdysozoa and Lophotrochozoa, an extra stimulus for studying this phylum has arisen. As one of the major phyla within Lophotrochozoa, Annelida are playing an important role in deducing the developmental biology of the last common ancestor of the protostomes and deuterostomes, an animal from which >98% of all described animal species evolved.