Activation of cardiac fibroblasts is a key event in the progression of cardiac fibrosis that leads to heart failure. However, the molecular mechanisms underlying mechanical stress-induced cardiac fibroblast activation are complex and poorly understood. This study demonstrates that Pellino1, an E3 ubiquitin ligase, was activated in vivo in pressure overloaded rat hearts and in cultured neonatal rat cardiac fibroblasts (NRCFs) exposed to mechanical stretch in vitro. Suppression of the expression and activity of Pellino1 by adenovirus-mediated delivery of shPellino1 (adv-shpeli1) attenuated pressure overload-induced cardiac dysfunction and cardiac hypertrophy and decreased cardiac fibrosis in rat hearts. Transfection of adv-shpeli1 also significantly attenuated mechanical stress-induced proliferation, differentiation and collagen synthesis in NRCFs. Pellino1 silencing also abrogated mechanical stretch-induced polyubiquitination of tumor necrosis factor-alpha receptor association factor-6 (TRAF6) and receptor-interacting protein 1 (RIP1) and consequently decreased the DNA binding activity of nuclear factor-kappa B (NF-κB) in NRCFs. In addition, Pellino1 silencing prevented stretch-induced activation of p38 and activator protein 1 (AP-1) binding activity in NRCFs. Chromatin Immunoprecipitation (ChIP) and luciferase reporter assays showed that Pellino1 silencing prevented the binding of NF-κB and AP-1 to the promoter region of transforming growth factor-β1 (TGF-β1) thus dampening TGF-β1 transactivation. Our data reveal a previously unrecognized role of Pellino1 in extracellular matrix deposition and cardiac fibroblast activation in response to mechanical stress and provides a novel target for treatment of cardiac fibrosis and heart failure.

Acute stretching increases postural stability in nonbalance trained individuals. J Strength Cond Res 26(11): 3095-3100, 2012-Studies into the relationship between acute stretching and maintenance of postural balance have been inconclusive. It was hypothesized that familiarization with the task and subsequent learning might be involved in the conflicting results. Therefore, this study was to designed determine if a regimen of static stretching exercises after a familiarization period would improve a person's ability to maintain a stabilometer in a neutral position and whether stretching had the same effect on individuals with extensive involvement with balancing tasks. Forty-Two college students (21 male, 21 female) and 10 surfers (all male) performed tests on a stabilometer on 2 separate days after 3 days of familiarization. Testing followed either 30 minutes of quiet sitting (nonstretched) or 30 minutes of stretching activities (stretched). Stretching exercises consisted of various assisted and unassisted static stretches of the muscles around the hip, knee, and ankle joints. Improved flexibility after the stretching exercises was demonstrated by significant (p , 0.05) 6.5 6 2.7 cm (mean 6 SD) increase in the sit and reach. Balance time for the students improved significantly by 11.4% (2.0-second increase), but the surfers had no significant change. Thus, stretching improved maintenance of balance perhaps by helping the subjects to eliminate the gross muscle contractions that caused large stabilometer displacements and to replace them with fine muscle contractions that caused little or no stabilometer displacements. However, it appears that experience doing balance tasks supplants any stretching benefit.

Indiana University-Purdue University Indianapolis (IUPUI) / Atherosclerosis is a chronic disease that happens mostly in aged people, and recently studies have showed many similarities between Hutchinson Gilford Progeria Syndrome (HGPS) cells and aging cells, implicating dysfunctions of lamin A/C in aging process and atherosclerosis, as HGPS is caused by a mutated form of lamin A/C. Blood flow in arteries is generating shear stress that is mostly applied on endothelial cells that align along inner blood vessel wall. At the same time, endothelial cells are also under stretch by periodic arterial pulses. Considering the fact that atherosclerosis is prone to developing at arterial branches with disturbed shear and increased stretch, it is highly possible that laminar flow and proper stretch force are regulating endothelium to function appropriately. In this thesis, the investigation of what effects laminar flow or cyclic stretch can bring to endothelial cells was conducted, and examination of lamin A/C expression under mechanical forces were elaborated and incorporated with cell senescence. Results showed that laminar shear stress and stretch force can regulate lamin A/C expression in different patterns, which were impaired in senescent cells.

The overall focus of this research project was to develop an in vitro tissue-engineered system that accurately reproduced the physiology of the sensory elements of the stretch reflex arc as well as engineer the myelination of neurons in the systems. In order to achieve this goal we hypothesized that myelinating culture systems, intrafusal muscle fibers and the sensory circuit of the stretch reflex arc could be bioengineered using serum-free medium formulations, growth substrate interface design and microfabrication technology. The monosynaptic stretch reflex arc is formed by a direct synapse between motoneurons and sensory neurons and is one of the fundamental circuits involved in motor control. The circuit serves as a proprioceptive feedback system, relaying information about muscle length and stretch to the central nervous system (CNS). It is composed of four elements, which are split into two circuits. The efferent or motor circuit is composed of an [alpha]-motoneuron and the extrafusal skeletal muscle fibers it innervates, while the afferent or sensory circuit is composed of a Ia sensory neuron and a muscle spindle. Structurally, the two muscular units are aligned in parallel, which plays a critical role modulating the system's performance. Functionally, the circuit acts to maintain appropriate muscle length during activities as diverse as eye movement, respiration, locomotion, fine motor control and posture maintenance. Myelination of the axons of the neuronal system is a vertebrate adaptation that enables rapid conduction of action potentials without a commensurate increase in axon diameter. In vitro neuronal systems that reproduce these effects would provide a unique modality to study factors influencing sensory neuronal deficits, neuropathic pain, myelination and diseases associated with myelination. In this dissertation, results for defined in vitro culture conditions resulting in myelination of motoneurons by Schwann cells, pattern controlled myelination of sensory neurons, intrafusal fiber formation, patterned assembly of the mechanosensory complex and integration of the complex on bio-MEMS cantilever devices. Using these systems the stretch sensitive sodium channel BNaC1 and the structural protein PICK1 localized at the sensory neuron terminals associated with the intrafusal fibers was identified as well as the Ca2+ waves associated with sensory neuron electrical activity upon intrafusal fiber stretch on MEMS cantilevers. The knowledge gained through these multi-disciplinary approaches could lead to insights for spasticity inducing diseases like Parkinson's, demyelinating diseases and spinal cord injury repair. These engineered systems also have application in high-throughput drug discovery. Furthermore, the use of biomechanical systems could lead to improved fine motor control for tissue-engineered prosthetic devices.

ABSTRACT Effect of Warm-Up Activity on Vertical Ground Reaction Forces in Basketball Players During Drop Jump Landings Jacob Hinkel-Lipsker Purpose: The purpose of this study was to examine the effect of certain warm-up activities on vertical ground reaction forces (GRFv) during a drop jump landing. Methods: Eight women and twelve men (mean age 22.6 ± 1.82 years) completed three warm-up activities on three separate days in a counterbalanced order: a passive stretching warm-up, a dynamic warm-up, and a no warm-up control. After completing each activity, participants were asked to perform eight drop jump landings on a force platform. GRFv data was sampled at 1000 Hz during each landing, and the variables analyzed were: peak forefoot and rearfoot magnitude, forefoot and rearfoot rate of loading, and impulse. Results: The dynamic warm-up had significantly greater values (p < 0.05) for forefoot peak magnitude, rearfoot peak magnitude, and forefoot rate of loading compared to the passive stretching and control conditions. Also, there were no significant differences among all activities for rearfoot rate of loading and impulse. Conclusions: The significantly greater values for forefoot peak magnitude, rearfoot peak magnitude, and forefoot rate of loading that the dynamic warm-up produced indicates that this activity may be effective in increasing muscular stiffness in the lower limbs. The failure of the passive stretching warm-up to reach significance indicates that this activity may not be effective in decreasing lower extremity muscular stiffness.

<p> An investigation of general Materials of Differential Type [MDT], and Motions With Constant Stretch History [MCSH] is presented. Rivlin-Ericksen tensors An are shown to result from a Taylor series expansion of the relative strain tensor Ct(T). Internal constraint in MDT is discussed. General Solutions of Motions of Differential Type are worked out. Dynamically possible stresses are found for certain irrotational motions. Theorems regarding necessary and sufficient conditions for MCSH are proved. A class of MCSH is introduced, and an approximate MCSH is suggested. Necessary equations regarding gradients of a scalar-valued tensor function are derived. </p> / Thesis / Master of Engineering (MEngr)

Wearable sensors have garnered considerable interest because of their potential for various applications. However, much less has been studied about the Stretchsense pressure sensor characteristics and its workability for industrial application to prevent potential risk situations such as accidents and injuries. The proposed study helps investigate Stretchsense pressure sensors' applicability for measuring hand-handle interface forces under static and dynamic conditions. The BendLabs sensors - a multi-axis, soft, flexible sensing system was attached to the wrist to evaluate the wrist angle deviations. In addition, the StretchSense stretch sensors were attached to the elbow joint to help estimate the elbow flexion/extension. The research tests and evaluates the real-time pressure distribution across the hand while performing given tasks and investigates the relationship between the wrist and elbow position and grip strength. The research provides objective means to assess the magnitudes of high pressures that may cause pressure-induced discomfort and pain, thereby increasing the hand's stress. The experiment's most significant benefit lies in its applicability to the actual tool handles outside the laboratory settings.

abstract: The Stretch Model is a model of first year composition (FYC) that “stretches” the first semester's class over two semesters in order to help writing students who arrive at university with low test scores to succeed in their composition courses. Originally piloted in 1994 at Arizona State University (ASU), the Stretch Model of composition has been found to be effective in terms of retention and persistence of first language (L1) writers (e.g., Glau, 1996; 2007). It has become known at ASU and abroad as the Stretch Program. Since 1997, a separate track of the Stretch Program has been solely for second language (L2) writers, and L2 writing students are now roughly 17% of the program's population. Until fairly recently, there was no attempt to collect L2 data to support the Stretch Program's claims for effectiveness for the L2 population. As many universities across the nation have garnered inspiration for their own programs ("Stretch Award" 2016), and L2 writers have the potential to be in any composition class (Matsuda, Saenkhum, & Accardi, 2013), it is imperative to include the voices of L2 writers in the analysis of the Stretch Program. This study addresses the need for L2 writers' voices to be included in the analysis of the Stretch Program at Arizona State University. From the quantitative analysis of 64,085 students’ institutional data records, and qualitative analysis of 210 student surveys, findings include L2 writers have the highest rates of passing, but the lowest rates of persistence in the three-semester first year composition requirement when compared to Stretch L1 students and the traditional FYC population. Survey data also lends L2 student perceptions to complicate the main features of the Stretch Program including perceived writing improvement, having the same teacher and classmates for two semesters, and having more time to work on their writing. The quantitative findings are consistent with Snyder’s (2017a) analysis of the 2012 fall Stretch Program L1 and L2 cohorts. / Dissertation/Thesis / Doctoral Dissertation English 2018

Die vorgelegte Dissertationsschrift dient der Identifizierung des Mechanismus, über welchen neonatale Kardiomyozyten der Ratte biaxialen zyklischen Stretch wahrnehmen. Angriffspunkt dafür bildeten sowohl Stretch Activated Ion Channels (SAIC) als auch die mit Integrinen assoziierte Focal Adhesion Kinase (FAK). Die Inhibition der SAIC erfolgte mit Gadolinium und eine Blockade der FAK konnte durch den FAK-Inhibitor II erreicht werden. Eigens angelegte Zellkulturen wurden unter definierten Parametern für 24 Stunden unter Einwirkung genannter Stoffe gestretcht und anschließend einer Analyse mittels Immunfluoreszenz und Western Blot unterzogen. Gestretchte Kardiomyozyten richteten sich schräg zur Achse der einwirkenden Kraft aus und wiesen eine Polarisierung von Connexin 43 auf, außerdem zeigte sich dessen gesteigerte Expression. Durch die Blockade der FAK konnte lediglich eine aufgehobene Polarisierung von Connexin 43 bei unveränderter Expression und Ausrichtung der Kardiomyozyten festgestellt werden. Auch die Mikrotubuli veränderten nach Stretch ihre Orientierung bezogen auf die Zellachse. Die zunächst annähernde Parallelität der Fasern zeigte sich nach Inhibition der FAK deutlich aufgelockert. Für die Aktinfilamente konnte dies nicht nachgewiesen werden. Die Integrine dienen demnach der Wahrnehmung von Stretch und vermitteln die Polarisierung von Connexin 43 sowie die Orientierung der Mikrotubuli über die FAK. Für die anderen genannten Prozesse ist die Aktivierung eines FAK-unabhängigen Integrin-Signalweges denkbar. Gadolinium hatte insgesamt keinen Effekt auf beschriebene Veränderungen, sodass ein Einfluss der SAIC auf Stretch-induzierte Veränderungen in Kardiomyozyten ausgeschlossen werden konnte. Gleichzeitig konnte durch die Beobachtung der Polarisierung von Microtubule Organizing Center, Kinesin und Golgi-Apparat die Hypothese der sich durch Stretch orientierenden neonatalen Kardiomyozyte unterstützt werden, welche die Voraussetzung für die Anordnung von Connexin 43 an den Zellpolen darstellen könnte. Sowohl die Selbstorganisation des Myokards im Rahmen der Embryogenese als auch die Pathophysiologie verschiedener kardialer Erkrankungen könnte dadurch womöglich besser verstanden werden.

Introduktion: Plyometrisk träning är en högintensiv träningsform för att förbättra atletisk prestation som exempelvis explosiv styrka och effektutveckling. Plyometrisk träning i vatten är däremot mindre undersökt men tidigare forskning tyder på att det verkar ha liknande effekter som landbaserad plyometrisk träning. Syfte: Litteraturundersökningens syfte är att undersöka om det finns en effekt av plyometrisk träning i vatten på hopphöjd, muskelstyrka och muskelömhet. Ytterligare ett syfte är att jämföra effekterna mellan plyometrisk träning i vatten med landbaserad plyometrisk träning på hopphöjd, muskelstyrka och muskelömhet. Metod: En systematisk sökning genomfördes i de vetenskapliga databaserna Pubmed och Web of Science. Utöver detta genomsöktes samtliga referenser på de artiklar som uppfyllde inklusionskriterierna. Resultat: Litteraturundersökningen visade att plyometrisk träning i vatten verkar ha en effekt på hopphöjd. Muskelstyrka och muskelömhet visade inget tydligt utfall. Plyometrisk träning i vatten verkar ha samma effekt på hopphöjd och muskelstyrka som landbaserad plyometrisk träning. Vattenbaserad plyometrisk träning verkar ge mindre muskelömhet jämfört med landbaserad plyometrisk träning. Konklusion: Det behövs mer forskning i området för att fastställa vilka faktorer som gör att vattenbaserad plyometrisk träning är lika effektiv som landbaserad träning för att förbättra hopphöjd. Det behövs mer forskning på plyometrisk träning i vatten associerad till muskelstyrka och muskelömhet för att få en tydligare bild av effekterna / Introduction: Effects of plyometric training to improve athletic performance such as explosive strength and power development are well-documented. However, less is known about the effects of aquatic plyometric training. Previous research suggests that it appears to have similar effects as land-based plyometric training. Purpose: The purpose of the literature review was to investigate if there is an effect of aquatic plyometric training on jump height, muscle strength and muscle soreness. Another aim was to compare the effects of plyometric training in water with land-based plyometric training on jump height, muscle strength and muscle soreness. Method: A systematic literature search was conducted in the scientific databases Pubmed and Web of Science. In addition, all references were manually searched on the articles that met the inclusion criteria. Results: The literature review shows that aquatic plyometric training seems to have an effect on jump height. Muscle strength and muscle soreness showed no clear outcome. Aquatic plyometric training seems to have the same effect on jump height and muscle strength as land-based plyometric training. Aquatic plyometric training seems to give less muscle soreness compared to land-based plyometric training. Conclusion: More research is necessary to determine which factors make aquatic plyometric training as effective as land-based plyometric training to improve jump height. More research is needed on aquatic plyometric training associated with muscle strength and muscle soreness to get a better understanding of the effects.