Fast Contraction Research Articles

An end-to-end atrial fibrillation detection by a novel residual-based temporal attention convolutional neural network with exponential nonlinearity loss

Atrial fibrillation (AF) is one of the most common abnormal heart rhythms, which is caused by the fast contraction of the two upper atria. Despite of the fact that convolutional neural network (CNN) has been applied to electrocardiogram analysis for AF rhythm, it cannot achieve the expected performance due to the lack of consideration for temporal features and the imbalance problem. In order to make the network concentrate on the learning of AF temporal features, we propose a residual-based temporal attention block (RTA-block). The RTA-block utilizes residual learning to generate temporal attention weights, which enhance informative features related to AF. Powered by the RTA-block, a residual-based temporal attention convolutional neural network (RTA-CNN) is further proposed for AF detection. The network can automatically focus on the parts with more sematic information to achieve better performance. In addition, we propose a novel exponential nonlinearity loss (EN-Loss), which addresses the imbalance problem by changing the nonlinearity of the loss function. We evaluated our framework on the single lead ECG classification dataset of The PhysioNet Computing in Cardiology Challenge 2017. The experimental results show that the proposed RTA-CNN with EN-Loss can obtain competitive results over the state-of-the-arts classification networks, which proves the method’s effectiveness.

Low-rank tensor ring learning for multi-linear regression

The emergence of large-scale data demands new regression models with multi-dimensional coefficient arrays, known as tensor regression models. The recently proposed tensor ring decomposition has interesting properties of enhanced representation and compression capability, cyclic permutation invariance and balanced tensor ring rank, which may lead to efficient computation and fewer parameters in regression problems. In this paper, a generally multi-linear tensor-on-tensor regression model is proposed that the coefficient array has a low-rank tensor ring structure, which is termed tensor ring ridge regression (TRRR). Two optimization models are developed for the TRRR problem and solved by different algorithms: the tensor factorization based one is solved by alternating least squares algorithm, and accelerated by a fast network contraction, while the rank minimization based one is addressed by the alternating direction method of multipliers algorithm. Comparative experiments, including Spatio-temporal forecasting tasks and 3D reconstruction of human motion capture data from its temporally synchronized video sequences, demonstrate the enhanced performance of our algorithms over existing state-of-the-art ones, especially in terms of training time.

Sound production, hearing sensitivity, and in-depth study of the sound-producing muscles in the cowfish (Lactoria cornuta).

The ability to produce sounds has been reported in various Ostraciidae but not deeply studied. In some Ostracion species, two different sound-producing muscles allow these boxfishes to produce two different kinds of sounds in a sequence. This study investigates sound production in another Indo-Pacific species, the longhorn cowfish Lactoria cornuta that also possesses two pairs of sonic muscles associated with the swim bladder: extrinsic sonic muscles (ESMs) and intrinsic sonic muscles (ISMs). The cowfish produces two kinds of sounds called hums and clicks. Hums are made of trains of low amplitude pulses that last for long periods of time, suggesting that they are produced by fatigue-resistant muscles, whereas clicks correspond to shorter sounds with greater amplitude than the hums, suggesting that they result from more powerful contractions. Ultra-structural differences are found between extrinsic and intrinsic sonic muscles. According to features such as long sarcomeres, long I-bands, a high number of mitochondria, and a proliferation of sarcoplasmic reticulum (SR), ESMs would be able to produce fast, strong, and short contractions corresponding to clicks (the shortest sounds with the greatest amplitude). ISMs have the thinnest cells, the smallest number of myofilaments that have long I-bands, the highest volume of mitochondria, and well-developed SR supporting these muscles; these features should generate fast and prolonged contractions that could correspond to the hums that can be produced over long periods of time. A concluding figure shows clear comparisons of the different fibers that were studied in L. cornuta. This study also compared the call features of each sound with the cowfish's hearing ability and supports L. cornuta was more sensitive to frequencies ranging between at least 100 and 400Hz with thresholds of 128-143dBre1µPa over this range, meaning that they are sensitive to the frequencies produced by conspecifics.

Attenuated activation of knee extensor muscles during fast contractions in older men and women.

Reduced physical function and increased risk of falls in older adults are accompanied by age-related reductions in torque development of leg muscles, although the mechanisms and potential sex differences are not understood. To determine the mechanistic origins (neural vs. muscular) for the age-related reduction in torque development, we compared the peak rates of torque development (RTD) during electrically-evoked and fast voluntary contractions of the knee extensors between young and older men and women. Sets of single- and double-pulse electrical stimulations evoked contractions of the knee extensor muscles in 20 young (23.0 ± 0.8years; 10 women) and 20 older adults (78.2 ± 1.5years; 10 women), followed by voluntary isometric knee extension contractions with torque development as fast as possible that matched the torque during electrically-evoked contraction (10-40% maximal torque). Peak RTD during fast-voluntary contractions was 41% less than electrically-evoked contractions (p < 0.001), but more so for older adults (44%) than young (38%, p = 0.04), with no sex differences. Peak RTD during fast-voluntary contractions was more variable between contractions for the older than young adults (77%MVC s-1 vs. 47%MVCs-1, p < 0.001). Additionally, older women exhibited greater variability than older men (81%MVCs-1 vs. 72%MVCs-1, p = 0.04) with no sex-related differences within the young adults. Older adults had slower and more variable RTD during voluntary contractions than young adults, particularly older women. The limited age-related differences in electrically-evoked RTD suggest the primary mechanism for the slower torque development of the knee extensor muscles in older men and women involve reduced neural activation.

Evaluation of Two Initialization Schemes for Simulating the Rapid Intensification of Typhoon Lekima (2019)

Two different initialization schemes for tropical cyclone (TC) prediction in numerical models are evaluated based on a case study of Typhoon Lekima (2019). The first is a dynamical initialization (DI) scheme where the axisymmetric TC vortex in the initial conditions is spun up through the 6-h cycle runs before the initial forecast time. The second scheme is a bogussing scheme where the analysis TC vortex is replaced by a synthetic Rankine vortex. Results show that although both initialization schemes can help improve the simulated rapid intensification (RI) of Lekima, the simulation employing the DI scheme (DIS) reproduces better the RI onset and intensification rate than that employing the bogussing scheme (BOG). Further analyses show the cycle runs of DI help establish a realistic TC structure with stronger secondary circulation than those in the control run and BOG, leading to fast vortex spinup and contraction of the radius of maximum wind (RMW). The resultant strong inner-core primary circulation favors precession of the midlevel vortex under the moderate vertical wind shear (VWS) and thus helps vortex alignment, contributing to an earlier RI onset. Afterwards, the decreased vertical shear and the stronger convection inside the RMW support the persistent RI of Lekima in DIS. In contrast, the reduced VWS is not well captured and the inner-core convection is weaker and resides farther away from the TC center in BOG, leading to slower intensification. The results imply that the DI effectively improves the prediction of the inner-core process, which is crucial to the RI forecast.

Ability to contract the pelvic floor muscles and association with muscle function in incontinent women.

Many women with pelvic floor dysfunction are unable to perform pelvic floor muscle (PFM) contraction. We aimed to assess the ability to contract the PFM and to evaluate the association with muscle function in Brazilian women with urinary incontinence. We conducted a retrospective cross-sectional study including incontinent women over the age of 18. The assessment of PFM contraction was carried out by bidigital palpation via the PERFECT scheme. We categorized our population as: group absent: women not able to contract the PFM with verbal instructions; group 1 (1st command): women able to contract their PFM after verbal instructions; group 2 (2nd command): women who needed additional training on PFM anatomy and functioning to contract them. We compared the groups regarding their PFM functionality. We used ANOVA for demographic data and Mann-Whitney test for association analyses and P value < 0.05 for statistical significance. Among 139 women included, 21 (15.1%) were not able to perform the contraction of the PFM. Sixty-five (46.7%) contracted their PFM voluntarily at the first command and 53 (38.1%) at the second command. There was a significant reduction in the PFM function in group 2 in terms of power (p < 0.001), endurance (p < 0.001) and fast contraction (p < 0.001) compared to group 1. A high percentage (53.2%) of women were not able to contract their PFM voluntarily without training in PFM anatomy and functioning. Those women had impaired muscle function compared to women able to perform PFM after receiving exclusively oral instructions.

New insights into the lacrimal pump

PurposeTo date, there are many theories about tear transport through the canaliculi of the draining lacrimal system into the lacrimal sac but only few with supportive data. It is certain that the function of the lacrimal part of orbicularis oculi muscle (Horner-Duverney's muscle) is indispensable for the transport of “used” tears. However, the muscle's exact structure and the mechanisms of its functions are as yet unclear. To obtain deeper insights we undertook the present study. MethodsUpper and lower canaliculi (including the entrance into the lacrimal sac) from donor cadavers were dissected. Some of the specimens were prepared for scanning electron microscopy (SEM) to analyze the course of muscle fibers surrounding the canaliculi. Others were sectioned for enzyme- (EHC) and immunohistochemistry (IHC) to learn about the distribution of slow and fast reacting muscle fibers in Horner-Duverney's muscle as well as to analyze the distribution of different neurotransmitters to learn more about the innervation of Horner-Duverney's muscle. Four tear duct systems taken from body donors were cut out en bloc after formalin fixation, serially sectioned and reconstructed using a newly developed technology for 3D reconstruction of histological serial sections named HiD® (Chimaera GmbH, Germany). Patients that had undergone dacryocystorhinostomy (DCR) were video-analyzed endonasally during active blinking, focusing on viewing the temporal wall of the lacrimal sac movement where the canaliculi penetrated the lacrimal sac. ResultsSEM revealed that muscle fibers of Horner-Duverney's muscle surround the vertical parts of the upper and lower canaliculus in a scissor like pattern whereas they ran in parallel to the first two thirds of the horizontal parts surrounding the respective canaliculus. Here, the muscle fibers were embedded in dense connective tissue forming a unique network. At the nasal third, muscle fibers left the canaliculi and ran to the posterior part of the fascia of the lacrimal sac and the lacrimal bone. EHC revealed that Horner-Duverney's muscle contained nearly an equal distribution of type I and type IIb muscle fibers compared to the superior rectus muscle which contains more type I and the masseter and iliopsoas muscles with more type IIb muscle fibers. IHC indicated presence of trigeminal, catecholaminergic and cholinergic nerve endings. 3D reconstructions supported the SEM data. Endonasal video analysis of patients after DCR with a nasally open lacrimal sac revealed bulging of the temporal wall of the lacrimal sac during blinking. On the basis of these findings, a modified lacrimal pump theory is proposed. ConclusionThe results support the hypothesis that contraction of Horner-Duverney's muscle leads to closure of the canaliculi in their first two thirds based on the special arrangement of muscle fibers and connective tissue fibers. This causes the tear fluid in the canaliculi to be pressed/transported towards the lacrimal sac. The medial third of the vertical portions of the canaliculi, the canaliculus communis and the intrasaccal portion of the canaliculus are compressed by the shortening and thickening of the Horner-Duverney muscle from dorsal, which leads to a compression of the canaliculi lumens in this part of the system, thereby pushing the lacrimal fluid further towards the lacrimal sac. The mix of fast contracting and fatigue resistant muscle fibers is ideally suited for the blink mechanism that is complexly regulated by the nervous system.

PhysIOpathology of NEuromuscular function rElated to fatigue in chronic Renal disease in the elderly (PIONEER): study protocol

BackgroundChronic Kidney Disease (CKD) is associated with reduced muscular strength resulting in profound fatigue. The physiopathology of these changes, their prevalence and evolution are still debated. Moreover, we have little data on elderly CKD patients. The present study protocol aims to 1) quantify the prevalence of low muscle strength (dynapenia) in a cohort of elderly patients with advanced CKD and to 2) characterize their force production coupled with electromyographic features and the symptoms of fatigue compared to a matched control group.MethodsThis is a case-control, prospective, interventional study. Inclusion criteria: age ≥ 60 years; CKD Stage 3b-5; clinical stability (i.e. no hospitalization and ≤ 25% in creatinine increase in the previous 3 months). Controls with normal kidney function will be matched in terms of age, gender and diabetes mellitus (requisite: estimated glomerular filtration rate ≥ 60 ml/min/1.73m2 available in the last 6 months). Exclusion criteria for cases and controls: neuromuscular disease, life expectancy < 3 months.The handgrip strength protocol is an intermittent test consisting in 6 series of 9 repetitions of 3-s sub-maximum contractions at 40% of the maximum voluntary contraction (MVC) and 2 s of resting time between contractions. Each series is separated by one fast sub-maximum contraction and one MVC. Strength is assessed with a high-frequency handgrip dynamometer paired with surface electromyography. Symptoms of fatigue are assessed using MFI-20 and FACIT-F questionnaires. In order to reach a statistical power of 96%, we plan to enroll 110 subjects in each group.DiscussionThe novelty of this study resides in the application of an already validated set of tests in a population in which this combination (dynamometer, electromyography and questionnaires) has not previously been explored. We expect a high prevalence of dynapenia and a higher fatigability in CKD patients. A positive correlation is expected between reported fatigue and fatigability.Better appreciation of the prevalence and the relationship between fatigability and a sensation of fatigue can help us target interventions in CKD patients to improve quality of life and survival.Trial registrationThe study was approved by Ethical Committee EST III n°20.03.01 and was recorded as a Clinical Trial (NCT04330807) on April 2, 2020.

Pre-rehabilitation of the pelvic floor before radiation therapy for cervical cancer: a pilot study.

The objective was to evaluate pelvic floor muscle (PFM) function regarding strength, activation and incontinence, approximately 1month before and after radiation therapy in women with cervical cancer. This was a pilot study of 49 women with cervical cancer at stages I to III. These women attended an educational session with a physical therapist who taught them to perform preventive pelvic floor muscle exercises (PFMEs; slow and fast contractions and the "knack") at home before, during and after radiation therapy. The women received instructions for performing PFME prior to radiation therapy. The modified Oxford scale, electromyography (EMG), the International Consultation on Incontinence Questionnaire Short Form to assess urinary incontinence and two questions for faecal and gas incontinence were used. Twenty-eight women (57%; mean age = 44years, range 27-66) completed the study, 21 (43%) were lost to follow-up. There was no significant change from baseline to post-radiation therapy in muscle strength, EMG records and incontinence (p > 0.05). The median of PFM strength was equal at baseline and after intervention (median = 2; IQR = 1). The results of this study suggest that pre-rehabilitation teaching PFMEs might be a protective factor for preserving PFM strength and preventing incontinence 1month after radiation therapy. It is a feasible intervention.

Observation of Ethanol-Induced Condensation and Decondensation Processes at a Single-DNA Molecular Level in Microfluidic Devices Equipped with a Rapid Solution Exchange System

Conformational transitions from secondary (e.g., B- to A-form DNA) to higher-order (e.g., coil to globule) transitions play important roles in genome expression and maintenance. Several single-molecule approaches using microfluidic devices have been used to determine the kinetics of DNA chromatin assembly because microfluidic devices can afford stretched DNA molecules through laminar flow and rapid solution exchange. However, some issues, particularly the uncertainty of time 0 in the solution exchange process, are encountered. In such kinetic experiments, it is critical to determine when the target solution front approaches the target DNA molecules. Therefore, a new design for a microfluidic device is developed that enables the instantaneous exchange of solutions in the observation channel, allowing accurate measurements of DNA conformational transitions; stepwise, ethanol-induced conformational transitions are revealed. Although full DNA contraction from coil to globule is observed with >50% ethanol, no outstanding change is observed at concentrations <40% in 10 min. With 50% ethanol solution, the DNA conformational transition passes through two steps: (i) fast and constant-velocity contraction and (ii) relatively slow contraction from the free end. The first process is attributed to the B to A conformational transition by gradual dehydration. The second process is due to the coil-globule transition as the free end of DNA starts the contraction. This globular structure formation counteracts the shear force from the microfluids and decelerates the contraction velocity. This real-time observation system can be applied to the kinetic analysis of DNA conformational transitions such as kinetics of chromatin assembly and gene expression.

P1163Correction of septal flash excursion with his bundle pacing

Abstract Funding Acknowledgements Grant from the Catalan Society of Cardiology Background His bundle pacing (HBP) directly stimulates the conduction system and could therefore correct asynchrony and evolve as a more physiological pacing approach. Septal flash (SF) is a fast contraction and relaxation of the septum occurring during the isovolumetric contraction period. It is a specific marker of cardiac dyssynchrony. Purpose Evaluate whether HBP corrects SF in patients with an indication for CRT or RV pacing. Methods A cohort of 20 consecutive patients undergoing HBP at our center was analyzed. HBP indications were: Group A (n = 3): left bundle branch block (LBBB) and left ventricular (LV) dysfunction (LV ejection fraction [LVEF] &amp;lt; 35%); Group B (n = 14): LV dysfunction (LVEF &amp;lt; 50%) and atrio-ventricular block requiring permanent pacing; Group C (ablate&amp;pace, n = 3): atrio-ventricular node ablation due to rapid atrial fibrillation. Patients in groups B and C had a RV backup lead implanted, in line with current recommendations. The presence of SF was analyzed in 2D-echocardiography at 15 days post-implant. SF excursion was quantified using M-mode in parasternal short and long axis views as the highest amplitude of the early inward motion. Baseline SF excursion was determined during intrinsic rhythm (group A) or RV pacing (groups B and C). For each patient, the pair of measurements (baseline, HBP) in the axis with the highest baseline SF was selected. Results Mean LVEFs were 21 ± 8%, 32 ± 6%, and 41 ± 18% for groups A, B and C, respectively. HBP shortened QRS duration by 42 ± 15 ms and 45 ± 23 ms in groups A (Baseline QRS - HBP QRS) and B + C (RV pacing QRS - HBP QRS), respectively. At baseline, all patients except 1 had SF (Fig. 1A). The mean SF excursion was 4.3 ± 1.9 mm, with SF excursion being larger in group A than in the RV-paced groups (6.3 ± 1.5 mm vs. 3.9 ± 1.8 mm for groups A and B + C, respectively, p = 0.04). HBP abolished SF in 3 patients (15%) and, on average, decreased SF excursion by 2.3 mm (95% CI 1.3-3.2), irrespective of pacing indication (Fig. 1B). The degree of SF excursion reduction after HBP significantly correlated with QRS shortening (r = 0.53, p = 0.024) (Fig 1C). Conclusions In conclusion, we show that HBP results in acute correction or decrease of SF, thereby improving LBBB- or RV-induced mechanical dyssynchrony. Abstract Figure. Septal Flash and His pacing

Pelvic floor disorders in women with premature ovarian insufficiency: a cross-sectional study.

This study aimed to investigate the prevalence of self-reported main pelvic floor disorders (PFD) (urinary incontinence [UI], pelvic organ prolapse [POP], and fecal incontinence [FI]) and its associated factors in women with premature ovarian insufficiency (POI) and a control group. This was a cross-sectional study wherein two groups were interviewed from August, 2017 to November, 2018-women with POI (n = 150) and a control group matched for age and body weight (n = 150). Sociodemographic variables and two questionnaires validated in Brazilian Portuguese language for PFD (Kings Health Questionnaire [KHQ] and Pelvic Floor Distress Inventory-20 [PFDI-20]) were used. Laycock's power, endurance, repetitions, fast contractions, every contraction timed (PERFECT) scale for pelvic floor muscle assessment was used in both groups. The prevalence of self-reported UI was 27.33% and 37.33% for POI and control groups (P > 0.05), respectively. There was no perceived difference regarding the prevalence of POP (9.33% POI group vs 8% control group; P = 0.682) and FI (8% POI vs 4% control group; P = 0.145). The P (power) (P = 0.46), E (endurance) (P = 0.91), R (repetitions) (P = 0.88), and F (fast contractions) (P = 0.19) values were statistically similar in both the groups. Multivariate analysis (n = 141) showed that higher weight (odds ratio [OR] 1.047 [1.018-1.076]; P < 0.001) and gravidity rates (OR 1.627 [1.169-2.266]; P < 0.01) were risk factors for UI and higher weight (OR 1.046 [1.010-1.084]; P = 0.01), and presence of comorbidities (OR 8.75 [1.07-71.44]; P < 0.01) were risk factors for POP in the POI group; there was no variable that was associated with FI. Women with POI did not have significant differences when compared with the control group regarding the prevalence of PFD and pelvic floor muscle assessment. Having higher weight and gravidity rates were associated with self-reported UI, while the presence of comorbidities and higher weight were risk factors for POP in the POI group. : Video Summary:http://links.lww.com/MENO/A555.

Temporal Invariance in SCA6 Is Related to Smaller Cerebellar Lobule VI and Greater Disease Severity.

Regulating muscle force and timing are fundamental for accurate motor performance. In spinocerebellar ataxia type 6 (SCA6), there is evidence that individuals have greater force dysmetria but display better temporal accuracy during fast goal directed contractions. Here, we test whether greater temporal accuracy occurs in all individuals with SCA6, and can be explained by lesser temporal variability. Further we examine whether it is linked to disease severity and specific degenerative changes in the cerebellum. Nineteen human participants with SCA6 (13 woman) and 18 healthy controls performed fast goal-directed ankle dorsiflexion contractions aiming at a spatiotemporal target. We quantified the endpoint control of these contractions, gray matter (GM) integrity of the cerebellum, and disease severity using the International Cooperative Ataxia Rating Scale (ICARS). SCA6 individuals exhibited lower temporal endpoint error and variability than the healthy controls (p = 0.008). Statistically, SCA6 clustered into two distinct groups for temporal variability. A group with low temporal variability ranging from 10 to 19% (SCA6a) and a group with temporal variability similar to healthy controls (SCA6b; 19-40%).SCA6a exhibited greater disease severity than SCA6b, as assessed with ICARS (p < 0.001). Lower temporal variability, which was not associated with disease duration (R2 = 0.1, p > 0.2), did correlate with both greater ICARS (R2 = 0.3) and reduced GM volume in cerebellar lobule VI (R2 = 0.35). Other cerebellar lobules did not relate to temporal variability. We provide new evidence that a subset of SCA6 with greater loss of GM in cerebellum lobule VI exhibit temporal invariance and more severe ataxia than other SCA6 individuals.SIGNIFICANCE STATEMENT Variability is an inherent feature of voluntary movement, and traditionally more variability in the targeted output infers impaired performance. For example, cerebellar patients present exacerbated temporal variability during multijoint movements, which is thought to contribute to their motor deficits. In the current work, we show that in a subgroup of spinocerebellar ataxia type 6 individuals, temporal variability is lower than that of healthy controls when performing single-joint fast-goal directed movements. This invariance related to exacerbated atrophy of lobule VI of the cerebellum and exacerbated disease severity. The relation between invariance and disease severity suggests that pathological motor variability can manifest not only as an exacerbation but also as a reduction relative to healthy controls.

Wound healing in immunocompromised dogs: A comparison between the healing effects of moist exposed burn ointment and honey

Background and Aim:Natural topical products have been used to enhance wound healing, especially in immunocompromised animals. The aims of this study were to evaluate and to compare the effects of moist exposed burn ointment (MEBO) and honey on the healing of full-thickness skin wounds in immunocompromised dogs.Materials and Methods:The study was conducted using 12 adults, apparently healthy mongrel dogs. Immunosuppression was induced in six dogs by oral administration of prednisone (2 mg/kg) and azathioprine (2 mg/kg), once a day for 21 days. On each dog, a total of 9, 1.5 cm in diameter full-thickness skin circular wounds were created aseptically in the thoracolumbar area under general anesthesia using customized skin punch biopsy kit. In a random fashion, three wounds in each dog were treatment using MEBO (contains b-sitosterol, baicalin, and berberine as active ingredients in a base of beeswax and sesame oil), honey or no treatment (control), once per day for 21 days. Wounds were grossly evaluated once a day for signs of inflammation or infection. In addition, biopsy specimens and digital imaging data of each wound were obtained on days 7, 14, and 21 for histopathological evaluation of the healing process.Results:Wounds in immunocompromised dogs appeared to heal significantly in a slower fashion than in non-immunocompromised counterparts. Digital analysis data showed that MEBO-treated wounds expressed better epithelialization area, faster contraction, and smaller wound area percentage when compared with honey-treated wounds. Histopathological analysis showed significantly higher angiogenesis scores in MEBO-treated wounds when compared with other treatments.Conclusion:Results of this study showed that MEBO resulted in significant enhancement of wound healing in both healthy and immunocompromised dogs. However, when compared to honey, the wound healing effect of MEBO was superior to that of honey.

Effect of eight weeks high intensity interval training on NRF-1, 2 and Tfam gene expressione levels in ST muscles in rats with myocardial infarction

Background: One of the side effects of myocardial infarction is the changes in slow contraction muscle phenotype to fast contraction due to decreased mitochondrial density. Mitochondrial biogenesis with its ability to create new mitochondria and increase mitochondrial density can minimize these complications. NRF-1,2 and Tfam are proteins that affect mitochondrial biogenesis that induces mitochondrial biogenesis by regulating mitochondrial DNA in the nucleus. Therefore, the aim of this study was to investigate the effect of eight weeks of high intensity interval training on expression of NRF-1,2 and Tfam genes in the rats with myocardial infarction. Methods: In this experimental study, which was done experimentally, 12 Wistar male rats with myocardial infarction were divided into two experimental groups (30 minutes on a treadmill on a regular basis and 4 minutes running with a severity of 90-85% VO2max and two minutes of active recovery with 50% -60% VO2max three days a week for eight weeks) and control (without exercise). The expression of NRF-1,2 and Tfam genes was studied as an effective factor in downstream mitochondrial biogenesis. Statistical data were analyzed with independent T test in spss18 (α≥0.05). Results: The results showed that the expression of NRF-1, NRF-2 and Tfam genes increased significantly (in at all P≤0.001). Conclusion: Generally, eight weeks of high intensity interval training increase mitochondrial biogenesis in slow muscle of myocardial infarction rats with effect on NRF-1, NRF-2 and Tfam genes.

Protective Effect Conferred by Isometric Preconditioning Against Slow- and Fast-Velocity Eccentric Exercise-Induced Muscle Damage.

We investigated if the same isometric preconditioning protocol (IPP) attenuates the magnitude of muscle damage induced by different maximal eccentric exercise protocols in the elbow flexors. Sixty-four untrained men were assigned to either two experimental or two control groups. Participants in the experimental groups performed an IPP prior to either slow (60°·s−1 – ISO + ECC-S) or fast (180°·s−1 – ISO + ECC-F) maximal eccentric contractions (MaxECC). Subjects in the control groups performed slow (ECC-S) or fast (ECC-F) MaxECC without IPP. Maximal isokinetic concentric torque (MVC), muscle soreness (SOR), and muscle thickness (MT) were assessed before, immediately after, and 1–4 days following the MaxECC. Significant (p < 0.05) group vs. time interactions were found for MVC (F = 4,517), SOR (F = 6,318), and MT (F = 1,863). The ECC-S group presented faster (p < 0.05) recovery of MVC and MT and less (p < 0.05) SOR at 96 h post-MaxECC compared with ECC-F group. No significant differences in MVC and MT were found between ECC-S and ECC-F groups following MaxECC. The ISO + ECC-S group showed faster (p < 0.05) recovery of MVC and SOR compared to the ECC-S group. No significant differences were evident between ISO + ECC-S and ECC-S in any variable. The ISO + ECC-F group showed faster (p < 0.05) recovery of all assessed variables compared with the ECC-F group. MVC was greater (p < 0.05) at 48–72 h, and SOR was less (p < 0.05) at 48–96 h in the ISO + ECC-F compared to the ECC-F group. No significant differences were evident between ISO + ECC-S and ISO + ECC-F for any variable. These results show that the IPP accelerated recovery of MVC and SOR for the slow-eccentric exercise condition and attenuated strength loss and SOR in addition to faster recovery of all assessed variables for the fast-eccentric exercise condition. Therefore, the IPP can be used as a strategy to attenuate and accelerate recovery of muscle damage induced by different-velocity eccentric exercises, resulting in greater protection against muscle damage induced by faster velocity.

Evaluating the Jones polynomial with tensor networks.

We introduce tensor network contraction algorithms for the evaluation of the Jones polynomial of arbitrary knots. The value of the Jones polynomial of a knot is reduces to the partition function of a q-state anisotropic Potts model with complex interactions, which is defined on a planar signed graph that corresponds to the knot. For any integer q, we cast this partition function into tensor network form, which inherits the interaction graph structure of the Potts model instance, and employ fast tensor network contraction protocols to obtain the exact tensor trace and thus the value of the Jones polynomial. By sampling random knots via a grid-walk procedure and computing the full tensor trace exactly, we demonstrate numerically that the Jones polynomial can be evaluated in time that scales subexponentially with the number of crossings in the typical case. This allows us to evaluate the Jones polynomial of knots that are too complex to be treated with other available methods. Our results establish tensor network methods as a practical tool for the study of knots.

Short-term Effects of Robot-Resistance Exercises on Muscle Strength and Activations: Types of Muscle Contraction and Speed of Contraction.

We developed the isokinetic exercise robot for single joint muscle training. The purpose of this study was to investigate the effects of contraction types (concentric vs. eccentric contractions) and contractile speeds (slow vs. fast contractions) controlled by the developed exercise robot on muscle strength and activations. Ten subjects voluntarily performed the biceps curls exercise by resisting the robot-driven loads. Results indicated that there was no significant change in muscular strength as a result of different type of contraction and contractile velocity. The effect of fatigue, however, might be detected due to decreased maximum moment and increased muscle activities. Further research on the optimal recovery time is needed in order to enhance utilization of exercise robot in fitness areas.

On the Shape of the Force-Velocity Relationship in Skeletal Muscles: The Linear, the Hyperbolic, and the Double-Hyperbolic.

The shape of the force-velocity (F-V) relationship has important implications for different aspects of muscle physiology, such as muscle efficiency and fatigue, the understanding of the pathophysiology of several myopathies or the mechanisms of muscle contraction per se, and may be of relevance for other fields, such as the development of robotics and prosthetic applications featuring natural muscle-like properties. However, different opinions regarding the shape of the F-V relationship and the underlying mechanisms exist in the literature. In this review, we summarize relevant evidence on the shape of the F-V relationship obtained over the last century. Studies performed at multiple scales ranging from the sarcomere to the organism level have described the concentric F-V relationship as linear, hyperbolic or double-hyperbolic. While the F-V relationship has most frequently been described as a rectangular hyperbola, a large number of studies have found deviations from the hyperbolic function at both ends of the F-V relation. Indeed, current evidence suggests that the F-V relation in skeletal muscles follows a double-hyperbolic pattern, with a breakpoint located at very high forces/low velocities, which may be a direct consequence of the kinetic properties of myofilament cross-bridge formation. Deviations at low forces/high velocities, by contrast, may be related to a recently discovered, calcium-independent regulatory mechanism of muscle contraction, which may also explain the low metabolic cost of very fast muscle shortening contractions. Controversial results have also been reported regarding the eccentric F-V relationship, with studies in prepared muscle specimens suggesting that maximum eccentric force is substantially greater than isometric force, whereas in vivo studies in humans show only a modest increase, no change, or even a decrease in force in lengthening contractions. This review discusses possible reasons reported in the literature for these discrepant findings, including the testing procedures (familiarization, pre-load condition, and temperature) and a potential neural inhibition at higher lengthening velocities. Finally, some unresolved questions and recommendations for F-V testing in humans are reported at the end of this document.

SapM mutation to improve the BCG vaccine: Genomic, transcriptomic and preclinical safety characterization

The Mycobacterium bovis Bacille Calmette Guérin (BCG) vaccine shows variable efficacy in protection against adult tuberculosis (TB). Earlier, we have described a BCG mutant vaccine with a transposon insertion in the gene coding for the secreted acid phosphatase SapM, which led to enhanced long-term survival of vaccinated mice challenged with TB infection. To facilitate development of this mutation as part of a future improved live attenuated TB vaccine, we have now characterized the genome and transcriptome of this sapM::Tn mutant versus parental BCG Pasteur. Furthermore, we show that the sapM::Tn mutant had an equal low pathogenicity as WT BCG upon intravenous administration to immunocompromised SCID mice, passing this important safety test. Subsequently, we investigated the clearance of this improved vaccine strain following vaccination and found a more effective innate immune control over the sapM::Tn vaccine bacteria as compared to WT BCG. This leads to a fast contraction of IFNγ producing Th1 and Tc1 cells after sapM::Tn BCG vaccination. These findings corroborate that a live attenuated vaccine that affords improved long-term survival upon TB infection can be obtained by a mutation that further attenuates BCG. These findings suggest that an analysis of the effectiveness of innate immune control of the vaccine bacteria could be instructive also for other live attenuated TB vaccines that are currently under development, and encourage further studies of SapM mutation as a strategy in developing a more protective live attenuated TB vaccine.