Biophysics Commons^™

Myocyte-Specific Overexpression Of Stromal Cell-Derived Factor 1 Facilitates Cardiac Regeneration And Improves Myocardial Function After Infarction In Mice., Detlef Ernst-Rudolf Obal

Electronic Theses and Dissertations

Background: Interruption of cardiac stromal cell-derived factor 1 (SDF1)-CXCR4 axis by chronic AMD3100 administration increased myocardial injury after permanent coronary artery ligation, demonstrating the important role of this chemokine in cardiac regeneration. Hypothesis: Cardiomyocyte-specific conditional overexpression of SDF prevents heart failure after permanent coronary ligation and facilitates cardiac regeneration. Methods and Results: Tetracycline-controlled, a-myosine heavy chain promoter directed overexpression of cardiac SDF resulted in a significant increase of SDF expression (SDF: 8.1 ng / g protein) compared with littermate WT mice (0.02 ng / g protein) four weeks after doxycycline withdrawal. SDF overexpression increased AKT and casein kinase 1 levels …

The Nh2-Hypervariable Region Modulates The Binding Affinity Of Troponin T For Tropomyosin, Chinthaka Kaushalya Amarasinghe

Wayne State University Theses

The troponin complex plays a central role in the allosteric function of sarcomeric thin filaments by enacting conformational changes during the Ca2+-regulated contraction and relaxation of striated muscle. The troponin subunit T (TnT) has two binding sites for tropomyosin (Tm) and is responsible for anchoring the troponin complex to the thin filament. Although the C-terminal and middle regions of the TnT polypeptide chain are highly conserved among the three muscle type isoforms, the hypervariable N-terminal region has evolutionarily diverged significantly among isoforms. Previous studies have shown that the N-terminal variable region fine-tunes Ca2+ regulation of muscle contractility via modulation of …

Computational Optogenetics: Empirically-Derived Voltage- And Light-Sensitive Channelrhodopsin-2 Model, John C. Williams, Jianjin Xu, Zhongju Lu, Aleksandra Klimas, Xuxin Chen, Christina M. Ambrosi, Ira S. Cohen, Emilia Entcheva

Department of Biomedical Engineering Faculty Publications

Channelrhodospin-2 (ChR2), a light-sensitive ion channel, and its variants have emerged as new excitatory optogenetic tools not only in neuroscience, but also in other areas, including cardiac electrophysiology. An accurate quantitative model of ChR2 is necessary for in silicoprediction of the response to optical stimulation in realistic tissue/organ settings. Such a model can guide the rational design of new ion channel functionality tailored to different cell types/tissues. Focusing on one of the most widely used ChR2 mutants (H134R) with enhanced current, we collected a comprehensive experimental data set of the response of this ion channel to different irradiances and voltages, …

From Gibbons To Gymnasts: A Look At The Biomechanics And Neurophysiology Of Brachiation In Gibbons And Its Human Rediscovery, Emma Et Pennock

Student Works

This conference paper serves to examine the evolutionary linkages of a brachiating ancestor in humans, the biomechanical and neurophysiology of modern day brachiators, and the human rediscovery of this form of locomotion. Brachiation is arguably one of the most metabolically effective modes of travel by any organism and can be observed most meritoriously in Gibbons. The purpose of the research conducted for this paper was to encourage further exploration of the neurophysiological similarities and differences between humans and non-human primates. The hope is that in spurring more interest and research in this area, further possibilities for rehabilitating brain injury will …

Aberrant Sialylation Alters Cardiac Electrical Signaling, Andrew Ednie

USF Tampa Graduate Theses and Dissertations

In the heart, electrical signaling is responsible for its rhythmicity and is necessary to initiate muscle contraction. The net electrical activity in a cardiac myocyte during a contraction cycle is observed as the action potential (AP), which describes a change in membrane potential as a function of time. In ventricular cardiac myocytes, voltage-gated sodium channels (Nav) and voltage-gated potassium channels (Kv) play antagonistic roles in shaping the AP with the former initiating membrane depolarization and the latter repolarizing it. Functional changes in the primary cardiac Nav isoform, Nav 1.5, or any one of the many Kv isoforms expressed in the …

Mechanism Of Catch Force: Tethering Of Thick And Thin Filaments By Twitchin., Thomas M Butler, Marion J Siegman

Department of Molecular Physiology and Biophysics Faculty Papers

Catch is a mechanical state occurring in some invertebrate smooth muscles characterized by high force maintenance and resistance to stretch during extremely slow relaxation. During catch, intracellular calcium is near basal concentration and myosin crossbridge cyctng rate is extremely slow. Catch force is relaxed by a protein kinase A-mediated phosphorylation of sites near the N- and C- temini of the minititin twitchin (approximately 526 kDa). Some catch force maintenance car also occur together with cycling myosin crossbridges at submaximal calcium concentrations, but not when the muscle is maximally activated. Additionally, the link responsible for catch can adjust during shortening of …

Endothelial Nitric Oxide Synthase And Growth Factor Regulation Of Flow-Mediated Vascular Remodeling, David Anthony Tulis

Theses and Dissertations in Biomedical Sciences

This study was designed to characterize structural remodeling of male Wistar rat mesenteric arteries exposed to elevated blood flow in vivo for 1, 3, or 7 days. A series of arterial ligations induced blood flow increases in ileal and second-order branch arteries compared to same animal control vessels. Neither mean carotid nor local mesenteric arterial pressures changed significantly pre- to post-ligation. The primary flow-mediated force in both vessels was shear stress with possible involvement of acute stretch-induced wall stress in the ileal artery. Significant luminal expansion and medial wall hypertrophy occurred in the ileal and second-order arteries in a time-dependent …

The Assessment Of Osteoinductivity Of Human Allograft Demineralized Bone Matrix By In Vivo And In Vitro Assay Models, Min Zhang

Theses and Dissertations in Biomedical Sciences

The osteoinductive potential (osteoinductivity) is a very important aspect of demineralized bone matrix (DBM) as a biomaterial. This study is directed at establishing qualitative and quantitative assays of the osteoinductivity of human DBM. Further aspects of this study include an assessment of the effects of the production process, matrix characterization, and donor related factors on osteoinductivity of the DBM.

Athymic mice were chosen as the animal model for use in the in vivo bioassay. Implantation of DBM in muscle pouches provided for much higher osteoinductivity (remineralization to 10% calcium) than subcutaneous site implantation (remineralization to 1.6% calcium). Histological observations revealed …

Mathematical Model Of Placental Oxygen And Carbon Dioxide Exchange, Ester P. Hill

Loma Linda University Electronic Theses, Dissertations & Projects

This model of placental CO₂ and O₂ exchange calculates the time course of changes in P_^CO2, [HCO₃^-], and [H⁺] in each of four "compartments" of placental exchange vessels: maternal erythrocytes, maternal plasma, fetal plasma and fetal erythrocytes. The changes in hemoglobin-bound CO₂ (carbamate) and oxyhemoglobin contents within the erythrocytes are also calculated, permitting consideration of the Haldane and Bohr effects. Equations were written to represent one-dimensional steady state CO₂ and O₂ diffusion between concurrent maternal and fetal capillaries and the subsequent hydration, carbamino and oxyhemoglobin reactions. The equations …