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Dominant Frequency (dominant + frequency)
Selected AbstractsHeterogeneity of Ventricular Fibrillation Dominant Frequency During Global Ischemia in Isolated Rabbit HeartsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2007Ch.B. , JANE CALDWELL M.B. Introduction: Ventricular fibrillation (VF) studies show that ECG-dominant frequency (DF) decreases as ischemia develops. This study investigates the contribution of the principle ischemic metabolic components to this decline. Methods and Results: Rabbit hearts were Langendorff-perfused at 40 mL/min with Tyrode's solution and loaded with RH237. Epicardial optical action potentials were recorded with a photodiode array (256 sites, 15 × 15 mm). After 60 seconds of VF (induced by burst pacing), global ischemia was produced by low flow (6 mL/min), or the solution changed to impose hypoxia (95% N2/5% CO2), low pHo (6.7, 80% O2/20% CO2), or raised [K+]o (8 mM). DF of the optical signals was determined at each site. Conduction velocity (CV), action potential duration (APD90), effective refractory period (ERP), activation threshold, dV/dtmax, and membrane potential were measured in separate experiments during ventricular pacing. During VF, ischemia decreased DF in the left ventricle (LV) (to [58 ± 6]%, P < 0.001), but not the right (RV) ([93 ± 5]%). Raised [K+]o reproduced this DF pattern (LV: [67 ± 12]%, P < 0.001; RV: [95 ± 9]%). LV DF remained elevated in hypoxia or low pHo. During ventricular pacing, ischemia decreased CV in LV but not RV. Raised [K+]o did not change CV in either ventricle. Ischemia and raised [K+]o shortened APD90 without altering ERP. LV activation threshold increased in both ischemia and raised [K+]o and was associated with diastolic depolarization and decreased dV/dtmax. Conclusions: These results suggest that during VF, decreased ECG DF in global ischemia is largely due to elevated [K+]o affecting the activation thresholds in the LV rather than RV. [source] Gastric myoelectrical activity post-chemoradiotherapy and esophagectomy: a prospective study using subscapular surface recordingDISEASES OF THE ESOPHAGUS, Issue 1 2004P. M. Lawlor SUMMARY., The aims of this study were to prospectively evaluate gastric function in esophageal cancer patients after chemoradiotherapy and following surgery, using cutaneous electrogastrography (EGG). Twenty-three patients with esophageal adenocarcinoma were recruited to the study. A subset of patients (n = 11) underwent neoadjuvant chemoradiotherapy and were also studied at 14 days after treatment. All patients underwent EGG studies prior to and following surgery, at 3 months postoperatively. Ten of these patients were also studied at medians of 6 months and 12 months after surgery. Twenty normal volunteers were used as controls. Post-operative EGG studies were monitored with a modified technique; the electrodes being placed in the subscapular region in the area of the transposed stomach. Following neoadjuvant treatment there was a significant increase in abnormal gastric myoelectrical activity involving changes in tachygastrias and decreased motility as measured by power ratio. Post-operatively there was a significant increase in bradygastria which persisted at 6 months but not at 12 months. There was a corresponding decrease in normogastria which persisted at 6 months and to a lesser extent at 12 months. Dominant frequency remained significantly depressed at 3, 6 and 12 months. Gastric myoelectrical activity is normal in untreated esophageal cancer. Neoadjuvant chemoradiotherapy causes a disruption to normal myoelectrical activity involving reduced motility and tachygastrias. Surgery causes a depression in dominant frequency with a reduced incidence of normogastria at 3 months and 6 months but with a tendency towards normality at 12 months. [source] Ranolazine Exerts Potent Effects on Atrial Electrical Properties and Abbreviates Atrial Fibrillation Duration in the Intact Porcine HeartJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2009KAPIL KUMAR M.D. Introduction: In vitro studies and ambulatory ECG recordings from the MERLIN TIMI-36 clinical trial suggest that the novel antianginal agent ranolazine may have the potential to suppress atrial arrhythmias. However, there are no reports of effects of ranolazine on atrial electrophysiologic properties in large intact animals. Methods and Results: In 12 closed-chest anesthetized pigs, effects of intravenous ranolazine (,9 ,M plasma concentration) on multisite atrial effective refractory period (ERP), conduction time (CT), and duration and inducibility of atrial fibrillation (AF) initiated by intrapericardial acetylcholine were investigated. Ranolazine increased ERP by a median of 45 ms (interquartile range 29,50 ms; P < 0.05, n = 6) in right and left atria compared to control at pacing cycle length (PCL) of 400 ms. However, ERP increased by only 28 (24,34) ms in right ventricle (P < 0.01, n = 6). Ranolazine increased atrial CT from 89 (71,109) ms to 98 (86,121) ms (P = 0.04, n = 6) at PCL of 400 ms. Ranolazine decreased AF duration from 894 (811,1220) seconds to 621 (549,761) seconds (P = 0.03, n = 6). AF was reinducible in 1 of 6 animals after termination with ranolazine compared with all 6 animals during control period (P = 0.07). Dominant frequency (DF) of AF was reduced by ranolazine in left atrium from 11.7 (10.7,20.5) Hz to 7.6 (2.9,8.8) Hz (P = 0.02, n = 6). Conclusions: Ranolazine, at therapeutic doses, increased atrial ERP to greater extent than ventricular ERP and prolonged atrial CT in a frequency-dependent manner in the porcine heart. AF duration and DF were also reduced by ranolazine. Potential role of ranolazine in AF management merits further investigation. [source] Changes in the Frequency Structure of a Mating Call Decrease Its Attractiveness to Females in the Cricket Frog Acris crepitans blanchardiETHOLOGY, Issue 8 2001Klaudia Witte In many species, females often prefer male signals that are more complex than in nature or beyond the range of calls naturally produced by conspecific males in spectral, temporal and amplitude features. In this study we examined both the ability of females to recognize signals outside the normal range of spectral frequency variation seen in male advertisement calls, and the influence of increasing call complexity by adding spectral components to enhance the attractiveness of a male advertisement call in the cricket frog Acris crepitans blanchardi, while keeping its amplitude constant. We used two different natural male call groups and created the following synthetic call groups: with a dominant frequency at 3500 Hz, i.e. at the normal dominant frequency with a frequency band within the sensitivity range of the inner ear basilar papilla; with a dominant frequency at 700 Hz, i.e. outside the normal range of variation and with a frequency band outside the sensitivity range of the basilar papilla but within the range of the amphibian papilla; with two dominant frequencies, one at 700 Hz and another at 3500 Hz, stimulating the basilar and amphibian papilla simultaneously. In double choice experiments we tested all combinations of the three call groups, and we tested the 3500 Hz call groups against the same natural call groups. Additionally, we tested the 700 Hz call groups against white noise to see whether these signals are meaningful in mate choice. Females preferred 3500 Hz call groups over all other call groups. The synthetic call group was as attractive to females as the same natural call group. The 700 Hz call group was not meaningful in mate choice. The combined (700 Hz + 3500 Hz) call group was significantly less attractive to females than the 3500 Hz call group. Thus, making a call more spectrally complex without increasing its overall amplitude decreases its attractiveness to cricket frog females. [source] Functional morphology of the sonic apparatus in the fawn cusk-eel Lepophidium profundorum (Gill, 1863)JOURNAL OF MORPHOLOGY, Issue 11 2007Michael L. Fine Abstract Recent reports of high frequency sound production by cusk-eels cannot be explained adequately by known mechanisms, i.e., a forced response driven by fast sonic muscles on the swimbladder. Time to complete a contraction-relaxation cycle places a ceiling on frequency and is unlikely to explain sounds with dominant frequencies above 1 kHz. We investigated sonic morphology in the fawn cusk-eel Lepophidium profundorum to determine morphology potentially associated with high frequency sound production and quantified development and sexual dimorphism of sonic structures. Unlike other sonic systems in fishes in which muscle relaxation is caused by internal pressure or swimbladder elasticity, this system utilizes antagonistic pairs of muscles: ventral and intermediate muscles pull the winglike process and swimbladder forward and pivot the neural arch (neural rocker) above the first vertebra backward. This action stretches a fenestra in the swimbladder wall and imparts strain energy to epineural ribs, tendons and ligaments connected to the anterior swimbladder. Relatively short antagonistic dorsal and dorsomedial muscles pull on the neural rocker, releasing strain energy, and use a lever advantage to restore the winglike process and swimbladder to their resting position. Sonic components grow isometrically and are typically larger in males although the tiny intermediate muscles are larger in females. Although external morphology is relatively conservative in ophidiids, sonic morphology is extremely variable within the family. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source] Accommodation microfluctuations and pupil size during sustained viewing of visual display terminalsOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2000L.S. Gray Summary Accommodation microfluctuations comprise two dominant frequencies; a low frequency component (LFC0.6 Hz) and a high frequency component (1.0 Hz Efficacy of laser Doppler flowmetry for the diagnosis of revascularization of reimplanted immature dog teethDENTAL TRAUMATOLOGY, Issue 2 2001Kallaya Yanpiset Abstract , This study was performed to assess if laser Doppler flowmetry (LDF) is an improved method for the detection of revascularization of replanted teeth. Teeth were extracted and reimplanted under different experimental conditions. LDF readings were taken before extraction and weekly for 3 months. In control teeth, LDF baseline readings were taken and then repeated after the apical blood vessels were cut surgically. At the end of 3 months it was determined radiographically and histologically whether revascularization had occurred, i.e. vitality had returned. Results: LDF readings correctly predicted the pulp status (vital vs. non-vital) in 83.7% of the readings. 73.9% (17 of 23) were correct for the vital teeth and 95% (19 of 20) were correct for the non-vital teeth. Fisher's exact test (2-tail) indicated that there was no significant association between the efficacy of LDF and tooth type (P=0.166), although P2 was the least accurate tooth tested. Wilcoxon's matched-pair signed rank test demonstrated that in the revascularized (vital) teeth, the flux value between the baseline and week 2 dropped significantly (P=0.0001), increased significantly from week 2 to week 4 (P=0.0001) and then decreased steadily until week 12. However, at week 12 the flux was still significantly higher than at week 2 (P=0.010). In the teeth that failed to revascularize, the flux value dropped significantly by weeks 1 and 2 (P=0.004 and P=0.0001, respectively). Flux values did not increase from week 2. A Fast Fourier Transform (FFT) analysis confirmed a pulse of dominant frequency of 2 Hz in the teeth that returned to vitality and the lack thereof in those that stayed non-vital. One tooth in which the flux value evaluation indicated a non-vital tooth but the radiographic/histologic findings showed vital (false negative) possessed a pulse of dominant frequency and proved by this method to have successfully revascularized. [source] Gastric myoelectrical activity post-chemoradiotherapy and esophagectomy: a prospective study using subscapular surface recordingDISEASES OF THE ESOPHAGUS, Issue 1 2004P. M. Lawlor SUMMARY., The aims of this study were to prospectively evaluate gastric function in esophageal cancer patients after chemoradiotherapy and following surgery, using cutaneous electrogastrography (EGG). Twenty-three patients with esophageal adenocarcinoma were recruited to the study. A subset of patients (n = 11) underwent neoadjuvant chemoradiotherapy and were also studied at 14 days after treatment. All patients underwent EGG studies prior to and following surgery, at 3 months postoperatively. Ten of these patients were also studied at medians of 6 months and 12 months after surgery. Twenty normal volunteers were used as controls. Post-operative EGG studies were monitored with a modified technique; the electrodes being placed in the subscapular region in the area of the transposed stomach. Following neoadjuvant treatment there was a significant increase in abnormal gastric myoelectrical activity involving changes in tachygastrias and decreased motility as measured by power ratio. Post-operatively there was a significant increase in bradygastria which persisted at 6 months but not at 12 months. There was a corresponding decrease in normogastria which persisted at 6 months and to a lesser extent at 12 months. Dominant frequency remained significantly depressed at 3, 6 and 12 months. Gastric myoelectrical activity is normal in untreated esophageal cancer. Neoadjuvant chemoradiotherapy causes a disruption to normal myoelectrical activity involving reduced motility and tachygastrias. Surgery causes a depression in dominant frequency with a reduced incidence of normogastria at 3 months and 6 months but with a tendency towards normality at 12 months. [source] Mating signal partitioning in multi-species assemblages: a null model test using frogsECOLOGY LETTERS, Issue 3 2003Andrew A. Chek Abstract Competitive partitioning of ,community' signal space has long been suggested to underlie diversification of mating signals. Selection or competitive exclusion is expected to reduce overlap of signals, minimizing destructive interference or reducing mismating. We used null models backed by simulation of type I and II error rates to test for evidence of structuring within 11 frog advertisement call assemblages. Within three assemblages, we found significant over-dispersion and regularity-of-spacing in dominant frequency and in pulse rate, consistent with a signal interference hypothesis and signal confusion hypothesis, respectively. Observed partitioning could represent signal evolution or could result from selection on assemblage composition. Most assemblages showed no acoustic partitioning possibly because: (i) partitioning is more readily apparent in female preference, calling times or sites, rather than call attributes; (ii) assemblages have not yet accommodated recently arrived species, or are compositionally unstable so that acoustic accommodation cannot occur; and (iii) evidence of partitioning is only likely where the acoustic space is densely packed. [source] Geographic Variation in Male Sexual Signals in Strawberry Poison Frogs (Dendrobates pumilio)ETHOLOGY, Issue 9 2007Heike Pröhl In this paper, we compare the advertisement calls of 207 neotropical strawberry poison frogs (Dendrobates pumilio) collected in 21 localities along a transect from northern Costa Rica to western Panama. Populations varied most in call duration and call rate, while pulse rate and duty cycle were less variable. Multivariate analyses showed that call variation followed a cline with higher call rates, shorter calls, lower duty cycles and higher pulse rates in the southeast. Body size decreased towards the southeast and explained most variation in dominant frequency, as well as some residual variation in call rate. We conclude that a combination of geography and morphology is largely responsible for call variation within this species. Two inferred bio-acoustic groups were roughly in accordance with two genetic groups, geographically separated in central Costa Rica. However, genetic distances among populations did not co-vary with call dissimilarity after correction for geographic distances. Thus, differences in calls between genetic groups are probably mainly a result of clinal variation. These findings agree with the general observation that bio-acoustic variation is often not (highly) associated with genetic divergence. Moreover, colour polymorphism observed among Panamanian populations was not reflected in a higher variability in call parameters relative to the monomorphic Costa Rican populations. [source] Female Preferences for Call Traits and Male Mating Success in the Neotropical Frog Physalaemus enesefaeETHOLOGY, Issue 2 2003Zaida Tárano Female preferences for male call traits may affect male mating success and the evolution of exaggerated secondary sexual traits. We used phonotaxis experiments to examine female preferences in the frog Physalaemus enesefae in relation to variation in male call duration, dominant frequency, intercall interval and amplitude (dB SPL). Females preferred long calls, low and average dominant frequency calls, short intercall intervals and more intense calls. We compared the patterns of female preferences with those of acoustic variation among males to test the prediction that properties with low within-male variation are associated with stabilizing or weakly directional female preferences, whereas properties with high within-male variation are associated with directional preferences. Females had weakly directional preferences for the dominant frequency of the call and strongly directional preferences for call duration and call rate. We also determined whether the temporal relationship between calls influenced preferences based on the dominant frequency of the call. Preferences for low-frequency over high-frequency calls disappeared when calls partially overlapped. Females preferred the leading call regardless of its dominant frequency. We also investigated mating patterns in the field. There was size-assortative mating, as male and female body sizes snout-vent length (SVL) were positively correlated. In addition, differences in the frequency distributions of body length (SVL) between mated and unmated males approached significance; lower SVL classes were underrepresented among mated males. These patterns may reflect female preferences for lower dominant frequency calls, as there is a negative correlation between male mass and the dominant frequency of the call. [source] Changes in the Frequency Structure of a Mating Call Decrease Its Attractiveness to Females in the Cricket Frog Acris crepitans blanchardiETHOLOGY, Issue 8 2001Klaudia Witte In many species, females often prefer male signals that are more complex than in nature or beyond the range of calls naturally produced by conspecific males in spectral, temporal and amplitude features. In this study we examined both the ability of females to recognize signals outside the normal range of spectral frequency variation seen in male advertisement calls, and the influence of increasing call complexity by adding spectral components to enhance the attractiveness of a male advertisement call in the cricket frog Acris crepitans blanchardi, while keeping its amplitude constant. We used two different natural male call groups and created the following synthetic call groups: with a dominant frequency at 3500 Hz, i.e. at the normal dominant frequency with a frequency band within the sensitivity range of the inner ear basilar papilla; with a dominant frequency at 700 Hz, i.e. outside the normal range of variation and with a frequency band outside the sensitivity range of the basilar papilla but within the range of the amphibian papilla; with two dominant frequencies, one at 700 Hz and another at 3500 Hz, stimulating the basilar and amphibian papilla simultaneously. In double choice experiments we tested all combinations of the three call groups, and we tested the 3500 Hz call groups against the same natural call groups. Additionally, we tested the 700 Hz call groups against white noise to see whether these signals are meaningful in mate choice. Females preferred 3500 Hz call groups over all other call groups. The synthetic call group was as attractive to females as the same natural call group. The 700 Hz call group was not meaningful in mate choice. The combined (700 Hz + 3500 Hz) call group was significantly less attractive to females than the 3500 Hz call group. Thus, making a call more spectrally complex without increasing its overall amplitude decreases its attractiveness to cricket frog females. [source] Effect of Electrical and Structural Remodeling on Spatiotemporal Organization in Acute and Persistent Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2002JOSEPH G. AKAR M.D. Spatiotemporal Organization in Atrial Fibrillation.Introduction: Atrial fibrillation (AF) may originate from discrete sites of periodic activity. We studied the effect of structural and electrical remodeling on spatiotemporal organization in acute and persistent AF. Methods and Results: Atrial effective refractory periods (AERPs) were recorded from five different sites at baseline and after pacing in acute AF (n = 8 dogs) and persistent AF (n = 8). Four persistent AF dogs subsequently were cardioverted to sinus rhythm to allow AERP recovery. Periodicity was quantified by calculating power spectra on left atrial electrograms obtained from a 64-electrode basket catheter. Left atrial size was measured by intracardiac echocardiography and structural changes were assessed by electron microscopy. Mean AERPs decreased after pacing in acute (128 ± 16 msec to 108 ± 29 msec, P < 0.001) and persistent AF (135 ± 16 msec to 104 ± 24 msec, P < 0.0001). AERP recovery was established after 7 days of sinus rhythm. Structural changes were mild in acute AF, severe in persistent AF, and remained severe after AERP recovery. A single dominant frequency was identified in 94% of acute AF bipoles, 57% in persistent AF, and 76% after AERP recovery. Average correlation coefficient was 0.82 among acute AF bipoles, 0.63 in persistent AF, and 0.73 after AERP recovery. Conclusion: Transition from acute to persistent AF is associated with loss of spatiotemporal organization. A single dominant frequency recruits the majority of the left atrium in acute AF. Persistent AF, however, is associated with structural remodeling and dominant frequency dispersion. Recovery of refractoriness only partially restores spatiotemporal organization, indicating a major role for structural remodeling in the maintenance of persistent AF. [source] Electrophysiologic Deterioration After One-Minute Fibrillation Increases Relative Biphasic Defibrillation EfficacyJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2000OSCAR H. TOVAR M.D. Biphasic Shocks and One-Minute Fibrillation. Introduction: The probability of survival decreases to 70% after 2 minutes of ventricular fibriltation. Bipliasic shocks are more effective than monophasic shocks in terminating short-duration (<30 sec) ventricular fibrillation. We tested the hypotheses that developing ischemia changes the electrophysiologic characteristics of fibrillation and that the relative efficacy of biphasic shocks increases as electrophysiologic characteristics deteriorate. Methods and Results: Monophasic (12 msec) and biphasic (6/6 msec) shocks (1 to 4 A) were tested in random order in isolated rabbit hearts after 1-minute ischemic fibrillation. Monophasic action potentials showed only a sporadic occurrence of electrical diastole after 5 seconds of fibrillation (24% of action potentials in the right ventricle and 18% in the left ventricle). After 60 seconds of fibrillation, diastole (17.83 ± 1.14 msec in the right ventricle and 21.52 ± 1.16 msec in the left ventricle) appeared after almost every action potential (P < 0.0001 compared with 5 sec), despite a lack of change in fibrillation cycle length and dominant frequency. Monophasie I50 was 2.89 A, and biphasic I50 was 1.4 A (77% reduction in energy). Normalized curve width decreased 28%. Retrospective analysis showed that shocks delivered early in the fibrillation action potential bad a greater probability of succeeding (89%) than shocks delivered late (30%; P < 0.001). Conclusion: After l-minute ischemic fibrillation, diastolic intervals occur during fibrillation. Therefore, defibrillation shocks have an approximately 29% probability of interacting with the fibrillation action potential during diastole. At this time, biphasic shocks produced a more deterministic defibrillation threshold and became even more efficacious (I50B/M = 0.48) than at short fibrillation durations (I50 B/M = 0.7). [source] Motion analysis of stereotyped hand movements in Rett syndromeJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 2 2003M. Wright Abstract Background Rett syndrome is a genetic developmental disorder, and stereotyped hand movements are a striking feature of this condition. The aim of the present study was to subject these movements to objective analysis and compare the results in one girl at different ages. Method The hand movements of a 10-year-old girl with Rett syndrome were subjected to accurate, three-dimensional (3D) computerized motion analysis and compared to two-dimensional (2D) video analysis of the same girl at 3 years of age. Results Three-dimensional computerized analysis revealed regular patterns with strong coupling between the hands. Frequency analysis showed a dominant frequency at 1.2 Hz, with a higher component at 2.4 Hz that may relate to the activity of basic rhythm generators. The same coupling characteristics were extracted from standard, 2D video recordings made at the same time as the 3D capture. Conclusion An informal video of the same girl taken when she was 3 years of age was analysed in the same way as the 2D video and showed the same characteristics, indicating the possible future use of automated video analysis for early screening and intervention evaluation. [source] An Assessment of the Terminology Used by Diplomates and Students to Describe the Character of Equine Mitral and Aortic Valve Regurgitant Murmurs: Correlations with the Physical Properties of the SoundsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2003Jonathan M. Naylor Twenty students and 16 diplomates listened to 7 recordings made from 7 horses with either aortic (n = 3) or mitral valve (n = 4) regurgitant murmurs. A total of 30 different terms were used to describe the character of these murmurs. However, only 4 terms were used in a repeatable and consistent manner. Most people described the character of a given mitral or aortic valve murmur with 1 or 2 terms. Diplomates drew from a pool of terms that was about half the size of that used by students,.1 ±2.0 terms for diplomats (mean ±1 SD) versus 13.1 ±1.8 terms for students (P < .001). Only blowing, honking, buzzing, and musical were markedly associated with the recording played. Frequency analysis of the murmurs allowed them to be classified as containing harmonics (n = 4) or not containing harmonics (n = 3). Blowing was used to describe murmurs without harmonics on 39 of 48 occasions and corresponds to the term noisy used in some older descriptions of equine murmurs. Honking, musical, and buzzing were markedly associated with murmurs that contained harmonics; these terms were used 23, 13, and 12 of a possible 64 times, respectively. The frequency of buzzing and honking murmurs (72.7 ±9.3 and 88.4 ±46.3 Hz, respectively) was markedly lower than that of musical murmurs (156.8 ±81.1 Hz) (all P values <.01). Honking murmurs (0.392 ±0.092 seconds) were shorter than those described as buzzing or musical (0.496 ±0.205 and 0.504 ±0.116 seconds, respectively). The data suggest that the terminology for the character of aortic and mitral regurgitant murmurs should be restricted to 4 terms: blowing, honking, buzzing, and musical. Honking, buzzing, and musical describe murmurs with a peak dominant frequency and harmonics; blowing describes murmurs without a peak frequency. Effective communication could be enhanced by playing examples of reference sounds when these terms are taught so that nomenclature is used more uniformly. Key words: Cardiac; Heart; Learning; Meaning. [source] Clinical features of Japanese male patients with type 1 autoimmune hepatitisALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2006Y. MIYAKE Summary Background Recently, unusual patients with autoimmune hepatitis, such as male patients, have increased. Aim To assess clinical feature of Japanese males with type 1 autoimmune hepatitis compared with females. Methods We investigated consecutive 160 patients with type 1 autoimmune hepatitis, who consisted of 20 males and 140 females, with a median age of 55 (16,79) years. Results Compared with females, males had a lower frequency of definite diagnosis according to the revised scoring system proposed by the International Autoimmune Hepatitis Group (40% vs. 85%) and lower serum levels of immunoglobulin G [1932 (1085,3850) mg/dL vs. 2624 (1354,6562) mg/dL]. However, they were similar in age, form of clinical onset, symptomatic concurrent autoimmune disease, human leucocyte antigen DR status and frequency of cirrhosis at the time of diagnosis. The normalization of serum alanine aminotransferase levels within 6 months after the introduction of corticosteroid treatment was lower in males compared with females (73% vs. 93%). Conclusions In male patients, a diagnosis of autoimmune hepatitis should be made carefully. In Japanese patients with a dominant frequency of human leucocyte antigen DR4, gender may affect the response to corticosteroid treatment. [source] Spectral electroencephalogram analysis in hepatic encephalopathy and liver transplantationLIVER TRANSPLANTATION, Issue 7 2002Alessia Ciancio The aim of this study is to evaluate the role of spectral electroencephalogram (EEG) analysis (SEEG) in quantitating brain dysfunction in cirrhotic patients, showing conditions of minimal hepatic encephalopathy (HE), and determining the impact of orthotopic liver transplantation (OLT) on its correction. SEEG was compared with visual EEG (VEEG) in 44 cirrhotic patients waiting for OLT and 44 healthy controls. Eighteen patients had overt HE, and 26 patients had no apparent HE. Twenty-one transplant recipients were reexamined 6 months after OLT. Computerized SEEG was performed by mean dominant frequency (MDF) and the occipital alpha-theta ratio, expressed as its logarithmic transformation (LogR). All patients underwent psychometric assessment. MDF and LogR correlated significantly with Child-Pugh score (P < .05) and the presence of HE (P < .0001). SEEG and VEEG determined minimal HE in 8 (31%) and 6 (23%) of 26 patients without overt HE, respectively. SEEG did not correlate with age, sex, cause of liver disease, portal hypertension, or psychometric test results. MDF and LogR improved in many transplant recipients. LogR was significantly lower in OLT candidates who died before OLT compared with OLT survivors. In conclusion, SEEG provides reliable quantitative information to evaluate the degree of HE and appears more sensitive than VEEG to discriminate a subclinical stage of HE. The improvement in SEEG results observed in transplant recipients confirms the reversibility of bioelectric brain dysfunction with restoration of liver functions. [source] 34 Senso-reflexory control of the gastric myoelectrical activity , effect of oral exposure to a sweet or a bitter taste on a multichannel electrogastrogramNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2006M DZIELICKI Aim:, To examine the effect of sensory stimulation with a sweet or a bitter taste on the interdigestive gastric myoelectrical activity (GMA) in humans. Methods:, Eighteen healthy subjects (10F, 8M) underwent on two separate days four-channel electrogastrographic recordings comprising three consecutive 35 min periods: (i) basal fasted, (ii) a stimulation epoch while a subject was chewing an agar cube soaked with a taste-delivering substance (saccharose for the sweet taste, quinine hydrochloride for the bitter taste), (iii) a post-stimulatory (recovery) epoch. An electrocardiogram was simultaneously registered for the purpose of the heart rate variability (HRV) analysis. Results:, Exposure to the sweet taste brought about an increase in the power of the high frequency (HF: 0.15,0.4 Hz) band of the power spectrum-analyzed HRV data. The bitter taste had no effect on the HRV. During the stimulation and the recovery epoch a statistically significant augmentation in the relative time share of tachy- and bradygastria within the multichannel electrogastrogram was found either with the sweet or the bitter taste. Whereas no any other modifications of the GMA were elicited by the sweet taste, the exposure to the bitter taste resulted in a statistically significant decrease in the relative time share of normogastria, a decline in the dominant frequency and the dominant power of the gastric slow waves, as well as a reduction in the percentage of the slow wave coupling. Conclusions:, (i) Exposure to the sweet taste elicits a vagal arousal expressed by an increase in the HF power, whereas the bitter taste does not affect the equilibrium between the parasympathetic and the sympathetic component of the autonomous nervous system; (ii) The increased relative time contribution of tachy- and bradygastria within the electrogastrogram during both the stimulation and the recovery epoch should be considered an unspecific phenomenon because it accompanied stimulation either with the sweet or the bitter taste; (iii) The inhibitory effect of the bitter taste on the GMA, reflected by a diminution in the dominant frequency and the dominant power of the gastric slow waves, as well as their reduced coupling, may be indicative of an evolutionary archetype of a warning reaction of the human (mammalian) organism towards this taste. [source] 35 Electrogastrography in healthy participants: comparison of children and adultsNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2006CA FRIESEN The current study examined whether electrogastrogram (EGG) patterns differ between children/adolescents and adults, including whether EGG recordings obtained from healthy children would be considered normal by standards established for adults. Twenty-eight healthy children (54% females; ages 8,17, M = 12.4 years) were evaluated and compared to 15 healthy adults. EGGs were recorded for 30 min in the fasting state and for 1 h following a standard meal. For both pediatric and adult participants, there was a significant increase in both the dominant frequency and the dominant power from the pre- to the post , prandial period (p < 0.001 for each). There was a significant post-prandial increase in the %normal slow waves in pediatric participants only (81.5 vs. 89.0% vs. p < 0.001). Children demonstrated a significantly lower mean fasting %normal slow waves (81.5% vs. 94.2%) and a significantly greater fasting % tachygastria (8.9% vs. 2.3%) than did adults. Other parameters did not differ. Using adult standards, the %normal slow waves were ,70% of recording time in 96% children in the fasting state and in 100% in the postprandial period. A postprandial power increase was seen in 89% of the children. In conclusion, while adults should not be used as controls in pediatric studies of EGG, our data would indicate that American Motility Society (AMS) consensus adult criteria for a normal EGG are appropriate to apply to children and adolescents when utilizing methodology and meal challenge similar to that used to establish the adult norms. [source] Centrifugal Gradients of Rate and Organization in Human Atrial FibrillationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2009DAVID E. KRUMMEN M.D. Introduction:Animal studies show that atrial fibrillation (AF) may emanate from sites of high rate and regularity, with fibrillatory conduction to adjacent areas. We used simultaneous mapping to find evidence for potential drivers in human AF defined as sites with higher rate and regularity than surrounding tissue. Materials and Methods:In 24 patients (age 61 ± 10 years; 12 persistent), we recorded AF simultaneously from 32 left atrial bipolar basket electrodes in addition to pulmonary veins (PV), coronary sinus, and right atrial electrodes. We measured AF cycle length (CL) by Fourier transform and electrogram regularity at each electrode, referenced to patient-specific atrial anatomy. Results:We analyzed 10,298 electrode-periods. Evidence for potential AF drivers was found in 11 patients (five persistent). In persistent AF, these sites lay at the coronary sinus and left atrial roof but not PVs, while in paroxysmal AF six of nine sites lay at PVs (P < 0.05). During ablation, a subset of patients experienced AF CL prolongation or termination with a focal lesion; in each case this lesion mapped to potential driver sites on blinded analysis. Conversely, sequential mapping failed to reveal these sites, possibly due to fluctuations in dominant frequency at driver locations in the context of migratory AF. Conclusions:Simultaneous multisite recordings in human AF reveal evidence for drivers that lie near PVs in paroxysmal but not persistent AF, and were sites where ablation slowed or terminated AF in a subset of patients. The future work should determine if real-time ablation of AF-maintaining regions defined in this fashion eliminates AF. [source] Opposite Effects of Myocardial Stretch and Verapamil on the Complexity of the Ventricular Fibrillatory Pattern: An Experimental StudyPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2000FRANCISCO J. CHORRO CHORRO, F.J., et al.: Opposite Effects of Myocardial Stretch And Verapamil on The Complexity of The Ventricular Fibrillatory Pattern: An Experimental Study. An experimental model is used to analyze the effects of ventricular stretching and verapamil on the activation patterns during VF. Ten Langendorff-perfused rabbit hearts were used to record VF activity with an epicardial multiple electrode before, during, and after stretching with an intraventricular balloon, under both control conditions and during verapamil (Vp) infusion (0.4,0.8 ,mol). The analyzed parameters were dominant frequency (FrD) spectral analysis, the median (MN) of the VF intervals, and the type of activation maps during VF (I = one wavelet without block lines, II = two simultaneous wavelets with block lines, III = three or more wavelets with block lines). Stretch accelerates VF (FrD: 22.8 ± 6.4 vs 15.2 ± 1.0 Hz, P < 0.01; MN: 48 ± 13 vs 68 ± 6 ms, P < 0.01). On fitting the FrD time changes to an exponential model after applying and suppressing stretch, the time constants (stretch: 101.2 ± 19.6 s; stretch suppression: 97.8 ± 33.2 s) do not differ significantly. Stretching induces a significant variation in the complexity of the VF activation maps with type III increments and type I and II decrements (control: I = 17.5%, II = 50.5%, III = 32%; stretch: I = 7%, II = 36.5%, III = 56.5%, P < 0.001). Vp accelerates VF (FrD: 20.9 ± 1.9 Hz, P < 0.001 vs control; MN: 50 ± 5 ms, P < 0.001 vs control) and diminishes activation maps complexity (I = 25.5%, II = 60.5%, III = 14%, P < 0.001 vs control). On applying stretch during Vp perfusion, the fibrillatory process is not accelerated to any greater degree. However, type I and II map decrements and type III increments are recorded, though reaching percentages similar to control (I = 16.5%, II = 53%, III = 30.5%, NS vs control). The following conclusions were found: (1) myocardial stretching accelerates VF and increases the complexity of the VF activation pattern; (2) time changes in the FrD of VF during and upon suppressing stretch fit an exponential model with similar time constants; and (3) although stretching and verapamil accelerate the VF process, they exert opposite effects upon the complexity of the fibrillatory pattern. [source] Remodelling of action potential and intracellular calcium cycling dynamics during subacute myocardial infarction promotes ventricular arrhythmias in Langendorff-perfused rabbit heartsTHE JOURNAL OF PHYSIOLOGY, Issue 3 2007Chung-Chuan Chou We hypothesize that remodelling of action potential and intracellular calcium (Cai) dynamics in the peri-infarct zone contributes to ventricular arrhythmogenesis in the postmyocardial infarction setting. To test this hypothesis, we performed simultaneous optical mapping of Cai and membrane potential (Vm) in the left ventricle in 15 rabbit hearts with myocardial infarction for 1 week. Ventricular premature beats frequently originated from the peri-infarct zone, and 37% showed elevation of Cai prior to Vm depolarization, suggesting reverse excitation,contraction coupling as their aetiology. During electrically induced ventricular fibrillation, the highest dominant frequency was in the peri-infarct zone in 61 of 70 episodes. The site of highest dominant frequency had steeper action potential duration restitution and was more susceptible to pacing-induced Cai alternans than sites remote from infarct. Wavebreaks during ventricular fibrillation tended to occur at sites of persistently elevated Cai. Infusion of propranolol flattened action potential duration restitution, reduced wavebreaks and converted ventricular fibrillation to ventricular tachycardia. We conclude that in the subacute phase of myocardial infarction, the peri-infarct zone exhibits regions with steep action potential duration restitution slope and unstable Cai dynamics. These changes may promote ventricular extrasystoles and increase the incidence of wavebreaks during ventricular fibrillation. Whereas increased tissue heterogeneity after subacute myocardial infarction creates a highly arrhythmogenic substrate, dynamic action potential and Cai cycling remodelling also contribute to the initiation and maintenance of ventricular fibrillation in this setting. [source]
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