Peak Contraction Research Articles

New electrohysterogram-based estimators of intrauterine pressure signal, tonus and contraction peak for non-invasive labor monitoring

Background: Uterine activity monitoring is an essential part of managing the progress of pregnancy and labor. Although intrauterine pressure (IUP) is the only reliable method of estimating uterine mechanical activity, it is highly invasive. Since there is a direct relationship between the electrical and mechanical activity of uterine cells, surface electrohysterography (EHG) has become a noninvasive monitoring alternative. The Teager energy (TE) operator of the EHG signal has been used for IUP continuous pressure estimation, although its accuracy could be improved. We aimed to develop new optimized IUP estimation models for clinical application. Approach: We first considered enhancing the optimal estimation of IUP clinical features (maximum pressure and tonus) rather than optimizing the signal only (continuous pressure). An adaptive algorithm was also developed to deal with inter-patient variability. For each optimizing signal feature (continuous pressure, maximum pressure and tonus), individual (single patient), global (full database) and adaptive models were built to estimate the recorded IUP signal. The results were evaluated by computing the root mean square errors (RMSe): continuous pressure error (CPe), maximum pressure error (MPe) and tonus error (TOe). Main results: The continuous pressure global model yielded IUP estimates with Cpe = 14.61 mm Hg, MPe = 29.17 mm Hg and Toe = 7.8 mm Hg. The adaptive models significantly reduced errors to CPe = 11.88, MPe = 16.02 and Toe = 5.61 mm Hg. The EHG-based IUP estimates outperformed those from traditional tocographic recordings, which had significantly higher errors (CPe = 21.93, MPe = 26.97, and TOe = 13.96). Significance: Our results show that adaptive models yield better IUP estimates than the traditional approaches and provide the best balance of the different errors computed for a better assessment of the labor progress and maternal and fetal well-being.

Muscle activation during maximum voluntary contraction and m-wave related in healthy but not in injured conditions: Implications when normalizing electromyography

BackgroundElectromyography signal amplitude is influenced by a variety of factors. Normalization strategies aimed at decreasing signal variability include using peak electromyography signal during a maximum voluntary contraction and peak-to-peak M-wave amplitude. However, whether these normalization methods are comparable has not been investigated in injured populations. This study investigated the relationship between peak signal during maximum voluntary contraction and M-wave amplitude in individuals with a unilateral Achilles tendon rupture. Secondarily, we observed whether the two normalizations strategies would yield similar results when evaluating between limb differences in muscle activity during a jump task. MethodsEleven individuals 1–3 years after a unilateral Achilles tendon rupture were included in this study. Surface electromyography was used on the medial and lateral gastrocnemii bilaterally. Peak maximum voluntary contraction, M-wave amplitude, and electromyography during a jumping task were collected. FindingsA strong relationship was observed between peak maximum voluntary contraction and M-wave amplitude on the uninjured (r = 0.71–0.88, P < 0.05) but not on the ruptured side (r = 0.41–0.44, P > 0.05). The two normalization techniques did not produce different results when comparing the uninjured and ruptured sides. InterpretationThe findings of this study suggest that M-wave normalization yields similar results as peak maximum voluntary contraction-normalized electromyography in uninjured conditions. M-wave normalization may be a useful strategy in an injured population where a maximal muscle contraction is unsafe or impaired.

Using a Stretch Sensor to Evaluate Muscle Contraction Timing During a Neuromuscular Control Screening Activity

PURPOSE: Stretch sensors are wearable devices that when applied over a muscle group, can measure the physical output of muscle deformation resulting from a muscle contraction. Electromyography (EMG) is the clinical standard for assessing the electrical signal identifying muscle activation. The well-established challenges in EMG data collection and analysis methods limit utility for wearable wide-spread neuromuscular control screening. The purpose of this study was to investigate the ability of stretch sensors to detect timing patterns of muscle contraction and compare time events to those collected through traditional clinical EMG. METHODS: 4 healthy subjects (mean age: 23.29 ±3.45 y) completed 5 repetitions of a unilateral partial squat with a stretch sensor and an EMG unit simultaneously applied to the dominant leg quadriceps muscle. Paired T-test and linear regression analyses assessed differences in key muscle contraction time events (Figure 1) for the stretch sensor (SS) and EMG. RESULTS: Relative times of peak contraction (r2= 0.99, mean relative error (RE)= 0.04), activation (r2= 0.98, RE= 0.14), and deactivation (r2= 0.92, RE= 0.35) displayed excellent correlation between the EMG and SS. Duration of ascent (p= 0.103, EMG: 1.14 ±0.46 s, SS: 1.36 ±0.27 s) and descent (p= 0.079, EMG: 1.38 ±0.49 s, SS: 1.14 ±0.37 s) squat phases and total contraction time (p= 0.95, EMG: 2.55 ±0.83 s, SS: 2.49 ±0.30 s) did not differ significantly between EMG and SS. Average within-subject variation was not significantly different for EMG timing of ascent (p= 0.56) and descent (p= 0.15) phases, and total contraction (p= 0.08). CONCLUSIONS: Our findings reveal similarities in time signatures between SS and EMG for assessing quadriceps activation during a standard neuromuscular screening activity. This suggests the potential for utility of SS evaluation of muscle activation timing. This study was supported in part by figur8 IncFigure 1:: Example of relative muscle contraction timing for stretch sensor and EMG signals during a repeated partial squal task. A 6 th order lower-pass Butterworth filter (3 Hz) and rectified TKEO function were applied to a raw EMG data. Threshold of activation/dectivation was defined as 3 standard deviations of a resting calibration trial.

Effects of Aortic Valve Replacement on Left Ventricular Diastolic Function in Patients With Aortic Valve Stenosis

The afterload increase imposed by severe aortic valve stenosis (AS) creates concentric left ventricular (LV) remodeling and diastolic dysfunction (DD), which are both markers of poor clinical outcome. Ideally, a correctly timed surgery for isolated AS can reverse the LV remodeling. However, data on LV DD after aortic valve replacement (AVR) are sparse and contrasting. Aims of the study are to define the markers of a favorable evolution of the DD at follow-up. Patients with severe isolated AS, scheduled for AVR were prospectively enrolled. Transthoracic echocardiography with DD assessment was performed before surgery, and at 12 months after surgery. Global LV longitudinal and circumferential strain, peak atrial longitudinal and contraction strain (PALS, PACS) were obtained at baseline. LV septal biopsy to assess fibrosis was performed at the time of AVR. Sixty-seven patients were enrolled, age 72 ± 8 years, 66% female, ejection fraction 61 ± 8%, E/e' 13 ± 6, PALS 23 ± 7%. Normal estimated left atrial pressure was detected in 19/67 (28%) versus 43/67 (64%) at follow-up (p <0.0001). In the 37 patients with biopsy available, fibrosis was 24 ± 12%. PALS and AS severity were correlated with LV fibrosis (R2 = 0.19; p = 0.006, and R2 = 0.15; p = 0.02, respectively). PALS (odds ratio: 1.19 [1.05 to 1.41], p = 0.02) and PACS (odds ratio: 1.24 [1.06 to 1.50], p = 0.006) were the only baseline noninvasive parameters independently associated with normal left atrial pressure at follow-up. Mean follow-up time was 791 ± 245 days, and 8 (12%) patients had cardiovascular events (death, hospital admission due to heart failure or ischemic disease, and onset of atrial fibrillation). Myocardial fibrosis (p = 0.05), baseline PALS (p = 0.004), and PACS (p = 0.03) were associated with cardiovascular events. In conclusion, LV diastolic function generally improves after AVR for severe AS. Baseline PALS, PACS, and LV fibrosis were related to the DD and clinical outcome at follow-up; these parameters might cue a better diastolic response to the afterload correction.

Estrogen regulation of cardiac cAMP-L-type Ca2+ channel pathway modulates sex differences in basal contraction and responses to \u03b22AR-mediated stress in left ventricular apical myocytes

Backgrounds/AimMale and female hearts have many structural and functional differences. Here, we investigated the role of estrogen (E2) in the mechanisms of sex differences in contraction through the cAMP-L-type Ca2+channel pathway in adult mice left ventricular (LV) apical myocytes at basal and stress state.MethodsIsolated LV apical myocytes from male, female (Sham) and ovariectomised mice (OVX) were used to investigate contractility, Ca2+ transients and L-type Ca2+ channel (LTCC) function. The levels of β2AR, intracellular cAMP, phosphodiesterase (PDE 3 and PDE 4), RyR2, PLB, SLN, and SERCA2a were compared among the experimental groups.ResultsWe found that (1) intracellular cAMP, ICaL density, contraction and Ca2+ transient amplitudes were larger in Sham and OVX + E2 myocytes compared to male and OVX. (2) The mRNA expression of PDE 3 and 4 were lower in Sham and OVX + E2 groups compared with male and OVX groups. Treatment of myocytes with IBMX (100 μM) increased contraction and Ca2+ transient amplitude in both sexes and canceled differences between them. (3) β2AR-mediated stress decreased cAMP concentration and peak contraction and Ca2+ transient amplitude only in male and OVX groups but not in Sham or OVX + E2 groups suggesting a cardioprotective role of E2 in female mice. (4) Pretreatment of OVX myocytes with GPR30 antagonist G15 (100 nM) abolished the effects of E2, but ERα and ERβ antagonist ICI 182,780 (1 μM) did not. Moreover, activation of GPR30 with G1 (100 nM) replicated the effects of E2 on cAMP, contraction and Ca2+ transient amplitudes suggesting that the acute effects of E2 were mediated by GPR30 via non-genomic signaling. (5) mRNA expression of RyR2 was higher in myocytes from Sham than those of male while PLB and SLN were higher in male than Sham but no sex differences were observed in the mRNA of SERCA2a.ConclusionCollectively, these results demonstrate that E2 modulates the expression of genes related to the cAMP-LTCC pathway and contributes to sex differences in cardiac contraction and responses to stress. We also show that estrogen confers cardioprotection against cardiac stress by non-genomic acute signaling via GPR30.

α1D–Adrenoceptor Mediated Components to Nerve‐Evoked Contractions in Mouse Vas Deferens

Contractions of the mouse vas deferens are mediated by α1‐adrenoceptors and P2X1‐purinoceptors (Brown et al., 1983). α1D‐Adrenoceptors are involved in the nerve‐evoked contraction to a single stimulus (Bexis et al., 2008). In this study, the role of these receptors in contractions to low and high frequency nerve stimulation have been investigated. Whole vas deferens from C57 mice were set up between electrodes in organ baths under 0.5 g tension in Krebs‐Henseleit solution, and stimulated electrically with 10 pulses at 1Hz or 40 pulses at 10 Hz using a Grass stimulator. The response to 1Hz stimulation consisted of discrete peaks of response corresponding to each stimulus. Threshold concentrations of the α1A‐adrenoceptor antagonist RS100329 (1nM) and the α1D‐adrenoceptor antagonist BMY7378 (100nM) significantly reduced contractions to the first pulse, and the non‐selective antagonist prazosin (10 nM) significantly reduced contractions to the first 4 pulses, at 1 Hz, but the combination of prazosin and the purinoceptor antagonist suramin produced marked inhibition of the response to all 10 pulses. The response to 10 Hz stimulation consisted of an early peak and later plateau of contraction. BMY7378 (100 nM) did not significantly affect the 10 Hz response but prazosin (10 nM) and RS100329 (1 nM) significantly reduced contractions, particularly the peak response, and higher concentrations markedly reduced responses. In the presence of the L‐type calcium channel blocker nifedipine, contractions to 10Hz stimulation were markedly reduced, particularly the later plateau component. In the presence of nifedipine, the peak response to 10 Hz stimulation was significantly reduced by prazosin (1nM) and by BMY7378 (100nM), demonstrating a small α1D‐adrenoceptor mediated component. In summary, contractions to 1 Hz stimulation have early α1A‐ and α1D‐adrenoceptor mediated components, but later responses are predominantly purinergic. Contractions even to 10 Hz stimulation have an early small α1D‐adrenoceptor component to the peak response, but both peak and plateau contractions largely involve α1A‐adrenoceptors and purinoceptors. The α1A‐adrenoceptor and purinoceptor components largely involve calcium entry through L‐type channels, but the α1D‐adrenoceptor mediated component involves T‐type calcium channels (Seto et al., 2010). In conclusion, the α1D‐adrenoceptor mediated component to both low and high frequency stimulation is very short‐lived, occuring in the first second of stimulation at low and high frequencies.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Double Regulation of Cardiac Excitation-Contraction Coupling and Oxidant Stress by Pirfenidone

Pirfenidone (PFD) is well-known for improving cardiac performance in models of disease. Thus, here we have investigated its functional effects on cardiomyocytes. Cells were cultured under control culture conditions or the presence of PFD (1 mM, 1-2d). Subsequently, they were subjected to electrical stimulation to examine the levels of intracellular Ca2+ and contractility. Remarkably, PFD improved both peak contraction and kinetics of shortening and relaxation. Moreover, the amplitude and kinetics of Ca2+ transients were also enhanced. Excitation-contraction coupling (ECC) was also investigated, under whole-cell patch-clamp. In keeping with a previous report, PFD elevated twofold the activity of CaV1.2. Besides, a similar increase in the magnitude of Ca2+ transients was also observed. Thus the gain of ECC was unaltered. Likewise, PFD did not alter the caffeine-sensitive Ca2+ store, indicating stimulation of Ca2+-induced Ca2+-release at constant sarcoplasmic reticulum Ca2+ load. Interestingly, although the expression of the Na+/Ca2+ exchanger (NCX) was unaffected, the decay of Ca2+ signal during caffeine applications was 50% slower in PFD-treated cells (compared with controls), indicating that PFD downregulates the NCX activity. PFD also inhibited the production of reactive oxygen species, under both, basal conditions and the presence of oxidant agents (acetaldehyde and peroxide hydrogen). Conversely, the amount of nitric oxide (NO) was either, increased (in atrial myocytes) or unchanged (in ventricular myocytes). Western-blot analysis showed that endothelial nitric oxide synthase expression remains unaffected, while a dual regulation was observed for that of neuronal isoform (nNOS) which consisted of inhibition and stimulation, in ventricular and atrial myocytes, respectively. Thus, in atrial cardiomyocytes, an up-regulation of nNOS was enough to augment the synthesis of NO. Apart from improving our knowledge of the molecular mechanisms of PFD action, these findings may also help in explaining the corresponding cardioprotective effects.

Legal Briefs: Tachysystole, Uterine Rupture, and a Bad Outcome.

EDITOR’S NOTE The Legal Briefs feature is based on actual malpractice cases with opinions of the plaintiff and defense physician experts interspersed throughout the case. The format of this feature does not provide evidence that supports or refutes each of these opinions. A 30-year-old gravida 3, para 1 woman presented at 41 weeks’ gestation for induction of labor. The pregnancy had been unremarkable. Two years before this pregnancy, the woman had undergone a cesarean after protracted labor that resulted in the delivery of a term healthy infant. For this pregnancy, a decision to induce labor and have a trial of labor after cesarean was agreed upon by the woman and her obstetrician. Increasing amounts of oxytocin were administered. Nine hours after induction was started, her contractions dramatically increased in frequency. The intervals between the peak of contractions varied between 60 and 90 seconds and the time between the end of one contraction and the beginning of the next was less than 1 minute in most cases. Long periods of tachysystole emerged. The obstetrician retained by the plaintiff stated that the treating obstetrician was required to decrease or discontinue the oxytocin when the contractions became too frequent. He explained that the time between the peak of one contraction and the next contraction needed to be at least 2 minutes and the interval between the end of one contraction and the beginning of the next needs to be at least 1 minute. He pointed out that these intervals were not maintained. He further explained that fetal gas exchange occurs during the rest phase between contractions and therefore, without proper rest intervals, gas exchange will eventually be compromised. He further pointed out that even the definition of tachysystole was met multiple times. He explained the definition of tachysystole was more than 5 contractions …

Menthol acts as a positive allosteric modulator on nematode levamisole sensitive nicotinic acetylcholine receptors

The ongoing and widespread emergence of resistance to the existing anti-nematodal pharmacopeia has made it imperative to develop new anthelminthic agents. Historically, plants have been important sources of therapeutic compounds and offer an alternative to synthetic drugs. Monoterpenoids are phytochemicals that have been shown to produce acute toxic effects in insects and nematodes. Previous studies have shown nicotinic acetylcholine receptors (nAChRs) to be possible targets for naturally occurring plant metabolites such as carvacrol and carveol. In this study we examined the effects of monoterpenoid compounds on a levamisole sensitive nAChR from Oesophagostomum dentatum and a nicotine sensitive nAChR from Ascaris suum. We expressed the receptors in Xenopus laevis oocytes and used two-electrode voltage-clamp to characterize the effect of various compounds on these cys-loop receptors. At 100 μM the majority of these compounds acted as antagonists. Interestingly, further experiments revealed that both 0.1 μM and 10 μM menthol potentiated acetylcholine and levamisole responses in the levamisole sensitive receptor but not the nicotine sensitive receptor. We also investigated the effects of 0.1 μM menthol on the contractility of A. suum somatic muscle strips. Menthol produced significant potentiation of peak contractions at each concentration of acetylcholine. The positive allosteric modulatory effects of menthol in both in vivo and in vitro experiments suggests menthol as a promising candidate for combination therapy with cholinergic anthelmintics.

Prognostic value of new imaging parameters in patients with hypertrophic cardiomyopathy: A prospective study

Hypertrophic cardiomyopathy (HCM) is a frequent hereditary cardiac disease and a major cause of sudden cardiac death (SCD). Although very useful, ESC risk score's predictive value has been interrogated since it was retrospective and did not include MRI parameters and new echocardiographic markers. To assess the additional value of new echocardiographic and MRI parameters in predicting SCD and outcome in patients with HCM. Between 2007 and 2017, 307 patients with HCM were prospectively included and followed for 1.63 years. In addition to conventional prognostic factors, all patients underwent cardiac MRI evaluation of late gadolinium enhancement (LGE), and echocardiographic measurements of LV and LA volumes and strains, including left atrial peak longitudinal strain (PALS) and left atrial peak contraction strain (PACS). Primary end-point was SCD or appropriate defibrillator therapy. Secondary end-point was a composite end-point including death, hospitalization for heart failure, new-onset of atrial fibrillation, need for septal ablation, myomectomy, or heart transplantation. Among the 307 patients, 6 patients (2%) died and the secondary end-point occurred in 65 (21%). Factors associated with SCD by univariate analysis were low LVEF [HR 0.91 (0.93–0.99)] impaired PALS [HR 0.86 (0.72–0.97)], and moderate mitral regurgitation (MR). Factors associated with the secondary end-point were impaired LV GLS [HR 1.23 (1.13; 1.35)], impaired LA 4-chamber PALS [HR 0.94 (0.91; 0.97)] and PACS [HR 0.91 (0.86; 95)], LA 2 chamber PALS [HR 0.93 (0.89; 0.96)] and PACS [HR 0.86 (0.83;0. 94)], as well as TTE and MRI MR, and presence of MRI LGE. Impaired LA 4-chamber PALS remained as an independent predictor for the composite end-point [HR 0.92 (0.87; 0.97)] after adjustment. This study suggests an additive prognostic value of an impaired LV and LA TTE strain, the presence of MR, and MRI LGE, to the classical ESC 7 recommended risk factors.

Long-Term Regulation of Excitation-Contraction Coupling and Oxidative Stress in Cardiac Myocytes by Pirfenidone.

Pirfenidone (PFD) is used to treat human pulmonary fibrosis. Its administration to animals with distinct forms of cardiovascular disease results in striking improvement in cardiac performance. Here, its functional impact on cardiac myocytes was investigated. Cells were kept 1–2 days under either control culture conditions or the presence of PFD (1 mM). Subsequently, they were subjected to electrical stimulation to assess the levels of contractility and intracellular Ca2+. The PFD treatment promoted an increase in both peak contraction and kinetics of shortening and relaxation. Moreover, the amplitude and kinetics of Ca2+ transients were enhanced as well. Excitation–contraction coupling (ECC) was also investigated, under whole-cell patch-clamp conditions. In keeping with a previous report, PFD increased twofold the density of Ca2+ current (ICa). Notably, a similar increase in the magnitude of Ca2+ transients was also observed. Thus, the gain of ECC was unaltered. Likewise, PFD did not alter the peak amplitude of caffeine-induced Ca2+ release, indicating stimulation of Ca2+-induced–Ca2+-release (CICR) at constant sarcoplasmic reticulum Ca2+ load. A phase-plane analysis indicated that PFD promotes myofilament Ca2+ desensitization, which is being compensated by higher levels of Ca2+ to promote contraction. Interestingly, although the expression of the Na+/Ca2+ exchanger (NCX) was unaffected, the decay of Ca2+ signal in the presence of caffeine was 50% slower in PFD-treated cells (compared with controls), suggesting that PFD downregulates the activity of the exchanger. PFD also inhibited the production of reactive oxygen species, under both, basal conditions and the presence of oxidative insults (acetaldehyde and peroxide hydrogen). Conversely, the production of nitric oxide was either increased (in atrial myocytes) or remained unchanged (in ventricular myocytes). Protein levels of endothelial and neuronal nitric oxide synthases (eNOS and nNOS) were also investigated. eNOS values did not exhibit significant changes. By contrast, a dual regulation was observed for nNOS, which consisted of inhibition and stimulation, in ventricular and atrial myocytes, respectively. In the latter cells, therefore, an up-regulation of nNOS was sufficient to stimulate the synthesis of NO. These findings improve our knowledge of molecular mechanisms of PFD action and may also help in explaining the corresponding cardioprotective effects.

Postactivation Potentiation Improves Acute Resistance Exercise Performance and Muscular Force in Trained Men.

Conrado de Freitas, M, Rossi, FE, Colognesi, LA, de Oliveira, JVNS, Zanchi, NE, Lira, FS, Cholewa, JM, and Gobbo, LA. Postactivation potentiation improves acute resistance exercise performance and muscular force in trained men. J Strength Cond Res 35(5): 1357-1363, 2021-The purpose of this study was to investigate the effects of heavy back squat (90% one repetition maximum [1RM]) postactivation potentiation (PAP) on acute resistance exercise performance and force production in recreationally trained men, and to verify the relationship between maximal strength and the PAP response. Ten resistance-trained men randomly completed 4 experimental trials: (a) back squats without PAP (No-PAP), (b) back squats with PAP, (c) maximum voluntary isometric contraction (MVIC) of the quadriceps without PAP, and (d) MVIC with PAP. Back squats were performed with 4 sets at 70% of 1 RM with 2 minutes of rest interval. The number of squats repetitions performed was recorded for each set, and a total number of repetitions were calculated to analyze performance. Maximum voluntary isometric contraction was measured using electronic dynamometer, and the peak force and mean force were recorded. Blood lactate concentration was analyzed presquat and postsquat exercise. Repetitions performed in the first set was significantly (p < 0.001) greater in the PAP condition (22.00 ± 5.14) compared with No-PAP (15.50 ± 5.10), which resulted in significantly (p = 0.001) more total repetitions performed in the PAP (56.20 ± 17.3) condition compared with No-PAP (48.80 ± 14.5). Maximum voluntary isometric contraction peak was higher in PAP than in No-PAP (PAP = 765.7 ± 147.8 vs. No-PAP = 696.8 ± 131.5 N, p = 0.006). No significant correlations were observed between back squat 1RM relative to body mass and the PAP response in squat and MVIC. There were no significant differences in lactate concentration between conditions. In conclusion, PAP resulting from a heavy load prior back squat exercise improved total volume during resistance exercise. In addition, PAP was effective to increase force production during MVIC, but there was no relationship between relative 1RM values and the PAP response in trained men.

OC04 BASELINE ATRIAL STRAIN RELATES TO POST-SURGICAL FOLLOW UP IN SEVERE AORTIC STENOSIS

Background: Diastolic dysfunction (DD) and left ventricular (LV) remodelling subsequent to increased afterload in severe aortic stenosis (AS) affect left atrial (LA) function. Aortic valve replacement (AVR) restores afterload and potentially reverse the LV modifications. However, no markers have been able to predict the LV remodelling and the post-surgical clinical events. Aim: to assess the relationship between baseline LA function and the diastolic function response and the clinical events following isolated AVR. Methods: patients undergoing AVR for AS were prospectively enrolled. A comprehensive transthoracic echocardiography was performed before surgery and at 1 year follow-up (FU). Baseline Peak atrial longitudinal and contraction strain (PALS, PACS) were obtained. During one year FU, cardiovascular (CV) events (death, hospital admission for heart failure, ischemic heart disease or atrial fibrillation [AF]) were registered. Results: Sixty-seven patients were enrolled, 72 ± 8years, female 56%, EF 60 ± 8%, E/e’ 13 ± 6, PALS 23 ± 8%. A normal/grade-I diastolic function was registered in only 19/67 (28%) at baseline, in contrast with 43/67 (64%) at 1-year echocardiographic FU (p &lt; 0.0001). Normal/grade-1 diastolic function at FU was associated only with baseline PALS (OR:1.19[1.05–1.41], p = 0.02) and PACS (OR:1.24[1.06–1.50], p = 0.006) During a mean FU of 2.4 ± 0.4 years, 10 (14%) patients had CV events. Events occurred in older patients (74 ± 5 vs. 71 ± 9 years, p = 0.3), with similar EF (61 ± 6% vs. 62 ± 12%, p = 0.7), reduced PALS (20 ± 4% vs. 24 ± 6%, p = 0.04) and PACS (10 ± 3% vs. 13 ± 3%, p = 0.002). Conclusions: impaired baseline LA function is related with CV events and echocardiographic findings following AVR, identifying a subset of patients with increased CV risk.

RF14 CONSEQUENCES OF PRESSURE OVERLOAD AS DETECTED BY LEFT ATRIAL AND VENTRICULAR STRAIN IN PATIENTS WITH SEVERE AORTIC STENOSIS

Background: Severe aortic stenosis (AS) exposes the left ventricle (LV) to an increased afterload, leading to concentric remodelling and subsequent diastolic dysfunction (DD). Fibrosis is the histological key feature. However, none of the conventional echocardiographic parameters is able to reveal the extent of LV remodelling. Aim: to evaluate the ability of speckle tracking echocardiography in detecting LV remodelling in AS patients. Methods: patients undergoing aortic valve replacement (AVR) for severe symptomatic AS were prospectively enrolled. Standard transthoracic echocardiography was performed before surgery. Global LV longitudinal and circumferential strain (GLS, GCS), peak atrial longitudinal and contraction strain (PALS, PACS) were measured. LV septal biopsies to assess fibrosis were performed during surgery. Results: Forty-three consecutive patients were enrolled, with a mean age 73 ± 6years, 58% female. Ejection fraction (EF) 61 ± 7%, aortic valve area (AVA) 0.72 ± 18 cm2, mean gradient (MG) 51 ± 14 mmHg. LV fibrosis was 22 ± 11%. Global longitudinal strain (GLS) 15 ± 4%, peak atrial longitudinal strain (PALS) 24 ± 6%, peak atrial contraction strain (PACS) 12 ± 4%. The only parameters associated with LV fibrosis were MG (r = 0.45, p = 0.004), GLS (r = 0.37, p = 0.02), PALS (r = 0.43, p = 0.004) and PACS (r = 0.35, p = 0.02). After adjusting for GLS and MG, PALS (p = 0.01) and PACS (p = 0.02) were independent predictors of LV fibrosis. The combination of PALS and GLS was the strongest predictor of LV fibrosis. Conclusions: speckle tracking echocardiography provides additional information to characterise the LV remodelling over conventional parameters. Our findings suggest that consequences of pressure overload in AS impact both on ventricular and atrial function, possibly acting through different pathophysiological mechanisms.

Clinical Utility and Prognostic Value of Right Atrial Function in Pulmonary Hypertension.

Background Although right atrial (RA) enlargement is an established marker for adverse outcomes, the prognostic importance of RA dysfunction independent of RA size in pulmonary arterial hypertension is not known. Methods and Results Study subjects with pulmonary arterial hypertension were prospectively enrolled from 2010 to 2014. RA function was measured using RA speckle-tracking longitudinal strain and strain rate (SR) during each phase of the cardiac cycle: (1) RA reservoir (peak longitudinal strain, peak systolic SR), (2) RA conduit (peak early diastolic SR), and (3) RA active contraction (peak active contraction strain, peak contraction SR). The primary outcome was a composite of time to hospitalization or death assessed on follow-up. A total of 63 subjects had complete echocardiographic data. Of these, 91% were females, and the mean age was 58±12 years. During the follow-up period (range: 1-58 months), 39 were hospitalized or had died. After multivariable adjustment for age, sex, and left atrial size, peak longitudinal strain, peak active contraction strain, and peak early diastolic SR were significantly associated with increased risk of the composite outcome ( P=0.0005, P=0.0167, and P=0.0054, respectively). Conclusions RA dysfunction independently predicts mortality and hospitalizations in patients with pulmonary arterial hypertension.

Association with right atrial strain with right atrial pressure: an invasive validation study.

Echocardiographic assessment of right atrial pressure (RAP) from inferior vena cava (RAPIVC) dimension may underestimate catheter-derived (RAPC). As right atrial (RA) deformation, measured by speckle tracking, is preload-dependent, we hypothesized that RA strain may improve estimation of RAPC. Right atrial strain components [RA reservoir function (ƐR), peak RA contraction (ƐCT) and RA conduit function (ƐCD)] were measured in 125 of 175 patients who had echocardiography and invasive measures of RAP (median difference 1day). To determine whether RA strain measures differentiated patients with correct vs incorrect RAPIVC assessment, categories with RAPIVC values < 3, 8 and > 15mmHg were compared with RAPC groups < 3, 4-7, 8-10, 11-14 and > 15mmHg. Non-invasively determined RAP was significantly lower (p = 0.001) than invasively determined RAPC, with a weak correlation (r = 0.35, p < 0.001). RA strain components were associated with RA size, RV function and IVC size. In those with RAPIVC > 15mmHg, half of patients were categorized into RAP < 10mmHg. There were no significant differences in RA characteristics that differentiated patients in whom echocardiographic estimation of RAP was inaccurate. Right atrial strain measures were feasible, and had associations with RA size, RV systolic function and IVC size. Right atrial strain was significantly different between those with normal vs raised pressure, but it did not identify those with incorrect echocardiographic assessment of RAP.

Aphrodisiac Activity of Ethanol Extract of Cratoxylum sumatranum (JACK) Blume Stems on Isolated Rat Corpus cavernosum

Cratoxylum sumatranum (Jack) Blume of the Hypericaceae family is known as “Bentaleng” by Dayak Benuaq. In ethnobotany, Cratoxylum sumatranum stems (CSS) is used as energy drink or aphrodisiac, but its effect has not been scientifically proven. Research objective to study the aphrodisiac activity of CSS extract by screening the aphrodisiac activity in vitro. Method: CSS was collected from Kutai Kertanegara Regency, East Kalimantan Province. Extraction was by maceration with ethanol solvent for three days. Re-maceration was done twice. In vitro screening of aphrodisiac activity used isolated rat corpus cavernosum. The organ was placed into a 10 mL chamber containing Krebs-Henselheit solution at pH 7.4, 37°C and aerated with carbogen gas. After acclimation, a contraction test was performed with phenylephrine solution and after reaching the peak of contraction at plateau the Control (solvent extract) or CSS ethanol extract was administerd at cumulatively increased concentration. Vasodilation activity was known if the contraction response was decreased after the extract’s administration and expressed in percent contraction with negative value. Results: CSS ethanol extract induce vasodilatory response on rat Corpus cavernosum blood vessels. Vasodilation activity is increasing with increasing concentration of extract given compared to Control. Conclusion the aphrodisiac activity of CSS ethanol extracts is directly through the vasodilation action mechanism on blood vessels in the rat corpus cavernosum.

Low-cost electromyography – Validation against a commercial system using both manual and automated activation timing thresholds

Widespread use of electromyography (EMG) as an assessment and biofeedback method may be limited by costly commercial systems. Low-cost devices are available; however their validity is unknown. This study determined the concurrent validity of a low-cost EMG on a microchip compared with a commercially available system during isometric and dynamic muscle contractions. Inter-tester, intra-session reliability of manual data extraction during data processing compared to a simple, automatic thresholding method using the Teager-Kaiser energy operator (TKEO) was also evaluated. 10 healthy women (age 28.1 ± 6.8 yrs, height 162.1 ± 6.8 cm, mass 60.3 ± 10.2 kg) were assessed simultaneously with a commercially available EMG system (Telemyo DTS) and a custom low-cost EMG system (Myoware Muscle Sensor) during voluntary isometric contractions, knee extension, squatting, stepping and jumping. Two surface electrode sets (connected to the low-cost and the commercial system) were placed end to end along the same Vastus Lateralis muscle fibre line. Peak and mean contraction intensity, and contraction duration were analysed. Overall the relative agreement between systems was excellent for peak muscle activation (ICC 0.77–0.96) and modest to excellent for mean muscle activation (ICC 0.68–0.95) and contraction duration (ICC 0.65–0.99). Inter-tester, intra-session reliability was excellent for peak contraction intensity (ICC > 0.99) and modest to excellent for mean contraction intensity, with the TKEO method primarily recording stronger agreement than the manual method. Poor to excellent inter-tester reliability occurred for contraction duration. Our findings indicate that a low-cost EMG system is comparable to a commercial system for assessing muscle activation, and that using the TKEO improved the reliability of timing related variables.

Impaired neural pathway in gastric muscles of patients with diabetes

To explore the pathogenic mechanism of diabetic gastropathy, we investigated differences in response to electrical field stimulation (EFS) of gastric muscles from diabetic and non-diabetic (control) patients. Gastric specimens were obtained from 34 patients and 45 controls who underwent gastrectomy for early gastric cancer. Using organ bath techniques, we examined peak and nadir values of contraction under EFS. To examine responses to purinergic and nitrergic inhibition without cholinergic innervation, atropine, MRS2500, and N-nitro-L-arginine (L-NNA) were added sequentially to the organ bath. Tetrodotoxin (TTX) was used to confirm that the responses to EFS were mediated via neural stimulation. In the absence of pharmacological agents, peak contraction amplitude was greater in non-diabetic controls compared to diabetics only in the distal longitudinal gastric muscles. However, the nadir was greater in controls than in patients in both proximal and distal gastric circular muscles. Addition of MRS2500 could not decrease the nadir in both controls and patients, both in the proximal and distal stomach. However, L-NNA completely reversed the relaxation. TTX had no further effect on nadir. In conclusion, impaired inhibitory nitrergic neural pathway in both proximal and distal stomach and impaired excitatory cholinergic neural pathway in the distal stomach may contribute to the pathogenic mechanism underlying diabetic gastropathy.

Ellipsometry-based combination of isothermal sorption-desorption measurement and temperature programmed desorption technique: A probe for interaction of thin polymer films with solvent vapor.

An environmental chamber equipped with an in situ spectroscopic ellipsometer, programmatic vapor pressure control, and variable temperature substrate holder has been designed for studying polymer coating behavior during an exposure to a solvent vapor and also for probing the residual solvent in the film afterwards. Both sorption-desorption cycle at a constant temperature and temperature programmed desorption (TPD) of the residual solvent manifest themselves as a change of the film thickness. Monitoring of ellipsometric angles of the coating allows us to determine the thickness as a function of the vapor pressure or sample temperature. The solvent vapor pressure is precisely regulated by a computer-controlled pneumatics. TPD spectra are recorded during heating of the film in an oil-free vacuum. The vapor pressure control system is described in detail. The system has been tested on 6-170 nm thick polystyrene, poly(methyl methacrylate), and poly(2-vinyl pyridine) films deposited on silicon substrates. Liquid toluene, water, ethanol, isopropanol, cyclohexane, 1,2-dichloroethane, and chlorobenzene were used to create a vapor atmosphere. Typical sorption-desorption and TPD curves are shown. The instrument achieves sub-monolayer sensitivity for adsorption studies on flat surfaces. Polymer-solvent vapor systems with strong interaction demonstrate characteristic absorption-desorption hysteresis spanning from vacuum to the glass transition pressure. Features on the TPD curves can be classified as either glass transition related film contraction or low temperature broad contraction peak. Typical absorption-desorption and TPD dependencies recorded for the 6 nm thick polystyrene film demonstrate the possibility to apply the presented technique for probing size effects in extremely thin coatings.