JA. Herzog^∗, TR. Leonard^†, A. Jinha^†, W. Herzog^†,‡

Molecular & Cellular Biomechanics, Vol.11, No.1, pp. 1-17, 2014, DOI:10.3970/mcb.2014.011.001

Abstract Titin is the third most abundant protein in sarcomeres and fulfills a number of mechanical and signaling functions. Specifically, titin is responsible for most of the passive forces in sarcomeres and the passive visco-elastic behaviour of myofibrils and muscles. It has been suggested, based on mechanical testing of isolated titin molecules, that titin is an essentially elastic spring if Ig domain un/refolding is prevented either by working at short titin lengths, prior to any unfolding of Ig domains, or at long sarcomere (and titin) lengths when Ig domain un/refolding is effectively prevented. However, these properties… More >

G.R. Baker¹

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.2, pp. 91-101, 2013, DOI:10.3970/cmes.2013.096.091

Abstract A vortex patch is a bounded region of uniform vorticity in twodimensional, incompressible, inviscid fluid flow. The streamfunction satisfies the Poisson equation with the vorticity acting as a source term. The standard formulation is to write the streamfunction as a convolution of the vorticity with the twodimensional free-space Greens function. A simple application of Greens theorem converts the area integral to a boundary integral. Numerical methods must then account for the singular nature of the boundary integral, and high accuracy is difficult when filamentation takes place, that is, when long, very thin filaments of vorticity… More >

Walter Herzog^∗, Tim Leonard^†, Venus Joumaa^‡, Michael DuVall^§, Appaji Panchangam^¶

Molecular & Cellular Biomechanics, Vol.9, No.3, pp. 175-192, 2012, DOI:10.3970/mcb.2012.009.175

Abstract Ever since the 1950s, muscle force regulation has been associated with the cross-bridge interactions between the two contractile filaments, actin and myosin. This gave rise to what is referred to as the "two-filament sarcomere model". This model does not predict eccentric muscle contractions well, produces instability of myosin alignment and force production on the descending limb of the force-length relationship, and cannot account for the vastly decreased ATP requirements of actively stretched muscles. Over the past decade, we and others, identified that a third myofilament, titin, plays an important role in stabilizing the sarcomere and More >

JUAN CARLOS CAVICCHIA^1*, MABEL FÓSCOLO¹ , JORGE IBAÑEZ¹, CHRISTOPHER LILLIG², FRANCISCO CAPANI³

BIOCELL, Vol.35, No.3, pp. 81-90, 2011, DOI:10.32604/biocell.2011.35.081

Abstract Junctional devices in Sertoli cells conform the blood-testis barrier and play a key role in maturation and differentiation of germ cells. The spacial distribution of ectoplasmic specializations of Sertoli cells was studied by β-actin immunolabelling, using laser confocal and transmission electron microscopy. For confocal microscopy, β-actin immunolabelling of ectoplasmic specializations was studied over the background of either prosaposin or glutaredoxin immunolabelling of the Sertoli cytoplasm. Labelling was found near the basal lamina, surrounding early spermatocytes (presumably in leptotene-zygotene) or at one of two levels in the seminiferous epithelium: (1) around deep infoldings of the Sertoli… More >

ROMINA J. BEVACQUA, RAFAEL FERNANDEZ-MARTIN, DANIEL F. SALAMONE

BIOCELL, Vol.35, No.1, pp. 1-7, 2011, DOI:10.32604/biocell.2011.35.001

Abstract Parthenogenetic embryos are an ethically acceptable alternative for the derivation of human embryonic stem cells. In this work, we propose a new strategy to produce bovine parthenogenetic embryos inhibiting the emission of the first polar body during in vitro maturation, and allowing the extrusion of the second polar body during oocyte activation. Cytochalasin B, an inhibitor of actin microfilaments, was employed during in vitro maturation to inhibit first polar body emission or during parthenogenetic activation to block second polar body emission. Only one polar body was inhibited in each strategy in order to keep the diploid… More >

Tianxiang Su^∗, Prashant K. Purohit^∗,†

Molecular & Cellular Biomechanics, Vol.8, No.3, pp. 215-232, 2011, DOI:10.3970/mcb.2011.008.215

Abstract Filaments under distributed loads are common in biological systems. In this paper, we study the thermo-mechanical properties of an extensible thermally fluctuating elastic filament under distributed forces. The ground state of the filament is solved first, followed by an investigation of the thermal fluctuations around the ground state. We first consider a special case where the tangential component of the distributed force t is uniform along the filament. For the force-extension relation in this case, we show that the filament is equivalent to one under end-to-end applied force F=tL0/2 where L0 is the length of… More >

K. Y. Volokh^*

Molecular & Cellular Biomechanics, Vol.8, No.3, pp. 195-214, 2011, DOI:10.3970/mcb.2011.008.195

Abstract All models are wrong, but some are useful. This famous saying mirrors the situation in cell mechanics as well. It looks like no particular model of the cell deformability can be unconditionally preferred over others and different models reveal different aspects of the mechanical behavior of living cells. The purpose of the present work is to discuss the so-called tensegrity models of the cell cytoskeleton. It seems that the role of the cytoskeleton in the overall mechanical response of the cell was not appreciated until Donald Ingber put a strong emphasis on it. It was… More >

Yoshitaka Shimada^∗,†, Taiji Adachi^∗,†,‡, Yasuhiro Inoue^∗,†, Masaki Hojo^∗

Molecular & Cellular Biomechanics, Vol.6, No.3, pp. 161-174, 2009, DOI:10.3970/mcb.2009.006.161

Abstract The actin filament, which is the most abundant component of the cytoskeleton, plays important roles in fundamental cellular activities such as shape determination, cell motility, and mechanosensing. In each activity, the actin filament dynamically changes its structure by polymerization, depolymerization, and severing. These phenomena occur on the scales ranging from the dynamics of actin molecules to filament structural changes with its deformation due to the various forces, for example, by the membrane and solvent. To better understand the actin filament dynamics, it is important to focus on these scales and develop its mathematical model. Thus,… More >

Eugenio Brusa¹, Matteo Nobile²

CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.2, pp. 155-190, 2009, DOI:10.3970/cmes.2009.048.155

Abstract Lightness of high pressure vessels is currently assured by composite materials. Construction of over-wrapped composite pressure vessels with inner metallic liner is for instance compatible with standards requirements of the hydrogen technology of energy storage. Therefore a typical layout manufactured by some industries consists of a cylindrical vessel with covering of carbon-epoxy laminates and metallic impermeable liner. To allow the filament winding of the composite fibres are used hoop and helical layers, respectively. A single nozzle is usually built. It requires that the vessel material is reinforced. This need imposes to have a variable thickness… More >

FRANCISCO CAPANI¹, EZEQUIEL SARACENO¹, VALERIA ROMINA BOTI¹, LAURA AON-BERTOLINO¹, JUAN CARLOS FERNÁNDEZ¹, FERNANDO GATO¹, MARIA SOL KRAUSE², LISANDRO GIRALDEZ³, MARK H. ELLISMAN⁴, HÉCTOR COIRINI^1,2

BIOCELL, Vol.32, No.1, pp. 1-8, 2008, DOI:10.32604/biocell.2008.32.001

Abstract Cellular and subcellular organization and distribution of actin filaments have been studied with various techniques. The use of fluorescence photo-oxidation combined with phalloidin conjugates with eosin has allowed the examination of the precise cellular and subcellular location of F-actin. Correlative fluorescence light microscopy and transmission electron microscopy studies of F-actin distribution are facilitated with this method for morphological and physiological studies. Because phalloidin-eosin is smaller than other markers, this method allows the analysis of the three-dimensional location of F-actin with high-resolution light microscopy, three-d serial sections reconstructions, and electron tomography. The combination of selective staining More >