Ekaterina Nagornyak

University of Washington

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Gerald H. Pollack

University of Washington

Hyok Yoo

University of Washington

F. A. Blyakhman

Ural Federal University

Ronnie Das

University of Washington

Adam D. Wexler

Medisch Centrum Leeuwarden

Chenyang Wang

Sichuan University of Science and Engineering

Charles E. Murry

University of Washington

Hyunjung Yi

Korea Institute of Science and Technology

Eun Hyun Ahn

Johns Hopkins University

Guozheng Shao

University of Washington

Cooperative Institutions

University of Washington

Seattle University

Institute for Stem Cell Biology and Regenerative Medicine

California Institute for Regenerative Medicine

Cardiovascular Research Center

Ural Federal University

Johns Hopkins University

Johns Hopkins Medicine

Medisch Centrum Leeuwarden

Water Technology (Australia)

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Effect of sarcomere length on step size in relaxed rabbit psoas muscle

Journal of Muscle Research and Cell Motility (2004)

Ekaterina Nagornyak F. A. Blyakhman Gerald H. Pollack

Myofibril

10.1023/b:jure.0000021375.57900.0d

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Citations (7)

Mechanism of attraction between like-charged particles in aqueous solution

Soft Matter (2009)

Ekaterina Nagornyak Hyok Yoo Gerald H. Pollack

Although it has been long known that like-charged particles attract one another in aqueous media, the mechanism underlying this counter-intuitive phenomenon has remained controversial. We tested the hypothesis put forth long ago by Langmuir and again by Feynman and by Ise, that the attraction between like-charged entities lies in an intermediate of unlike charges. Tests were facilitated by the observation that the attractive forces could be confirmed between widely separated particles of macroscopic size. Two approaches showed comparable results. In the first, pH-sensitive dyes showed intermediate zones of opposite charge: an accumulation of protons was found between negatively charged spheres, whereas between positively charged spheres the intermediate zone contained OH−groups. In the second and complementary approach, microelectrode measurements showed that in between negatively charged spheres, the electrical potential was relatively positive, whereas between positively charged spheres it was relatively negative. Hence, both approaches confirm theoretical expectations. The large number of unlike charges lying in between the like-charged spheres may come from the build-up of the recently reported "exclusion zone" surrounding each particle.

Aqueous medium

Particle (ecology)

Suspension

Aqueous suspension

10.1039/b905080a

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Citations (41)

Connecting filament mechanics in the relaxed sarcomere

Journal of Muscle Research and Cell Motility (2006)

Ekaterina Nagornyak Gerald H. Pollack

Myofibril

10.1007/s10974-005-9036-3

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Citations (3)

Automatic step-detection algorithm for analysis of sarcomere dynamics

Computer Methods in Biomechanics & Biomedical Engineering (2008)

Chenyang Wang Ekaterina Nagornyak Ronnie Das Gerald H. Pollack

Motile systems exhibit a stepwise nature, seen most prominently in muscle contraction. A novel algorithm has been developed that detects steps automatically in sarcomere-length change data and computes their size. The method is based on a nonlinear filter and a step detection protocol that detects local slope values in comparison to a threshold. The algorithm was first evaluated using artificial data with various degrees of Gaussian noise. Steps were faithfully detected even with significant noise. With actual data, the algorithm detected 2.7 nm steps and integer multiples thereof. The results confirm a quantal 2.7 nm step-size reported earlier. As stepwise phenomena become increasingly evident, automatic step-detection algorithms become increasingly useful since the limiting factor is almost always noise. The algorithm presented here offers a versatile and accurate tool that should be useful not only within muscle contraction and motility fields, but in fields which quantal phenomena play a role.

Limiting

10.1080/10255840802213256

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Citations (0)

Stepwise Length Changes in Single Invertebrate Thick Filaments

Biophysical Journal (2005)

Ekaterina Nagornyak F. A. Blyakhman Gerald H. Pollack

Byssus

Tension (geology)

10.1529/biophysj.105.069864

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Citations (6)

Contraction-Induced Changes in Hydrogen Bonding of Muscle Hydration Water

The Journal of Physical Chemistry Letters (2014)

Hyok Yoo Ekaterina Nagornyak Ronnie Das Adam D. Wexler Gerald H. Pollack

Protein–water interaction plays a crucial role in protein dynamics and hence function. To study the chemical environment of water and proteins with high spatial resolution, synchrotron radiation-Fourier transform infrared (SR-FTIR) spectromicroscopy was used to probe skeletal muscle myofibrils. Observing the OH stretch band showed that water inside of relaxed myofibrils is extensively hydrogen-bonded with little or no free OH. In higher-resolution measurements obtained with single isolated myofibrils, the water absorption peaks were relatively higher within the center region of the sarcomere compared to those in the I-band region, implying higher hydration capacity of thick filaments compared to the thin filaments. When specimens were activated, changes in the OH stretch band showed significant dehydrogen bonding of muscle water; this was indicated by increased absorption at ∼3480 cm–1 compared to relaxed myofibrils. These contraction-induced changes in water were accompanied by splitting of the amide I (C═O) peak, implying that muscle proteins transition from α-helix to β-sheet-rich structures. Hence, muscle contraction can be characterized by a loss of order in the muscle–protein complex, accompanied by a destructuring of hydration water. The findings shed fresh light on the molecular mechanism of muscle contraction and motor protein dynamics.

Myofibril

10.1021/jz5000879

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Citations (13)

STEP SIZE IN ACTIVATED RABBIT SARCOMERES IS INDEPENDENT OF FILAMENT OVERLAP

Journal of Mechanics in Medicine and Biology (2004)

Ekaterina Nagornyak Gerald H. Pollack F. A. Blyakhman

Investigations carried out on single cardiac and bumblebee myofibrils have shown stepwise sarcomere-length change of ~2.7 nm. 1 We have carried out parallel measurements on single myofibrils from rabbit psoas muscle. Activated specimens were released or stretched using a motor-imposed ramp. With a high-resolution algorithm, we found that step sizes were always integer multiples of 2.7 nm, whether the length change was positive or negative, and independent of ramp velocity. Also, the influence of initial sarcomere length was studied, and found to be negligible. The value 2.7 nm, seen consistently, is equal to the linear repeat of actin monomers along the thin filament, a result that ties dynamical events to molecular structure, and places narrow constraints on any proposed molecular mechanism.

Myofibril

10.1142/s0219519404001181

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Citations (2)

Micro- and nano-patterned conductive graphene–PEG hybrid scaffolds for cardiac tissue engineering

Chemical Communications (2017)

Alec S.T. Smith Hyok Yoo Hyunjung Yi Eun Hyun Ahn Justin Daho Lee

A lack of electrical conductivity and structural organization in currently available biomaterial scaffolds limits their utility for generating physiologically representative models of functional cardiac tissue. Here we report on the development of scalable, graphene-functionalized topographies with anisotropic electrical conductivity for engineering the structural and functional phenotypes of macroscopic cardiac tissue constructs. Guided by anisotropic electroconductive and topographic cues, the tissue constructs displayed structural property enhancement in myofibrils and sarcomeres, and exhibited significant increases in the expression of cell-cell coupling and calcium handling proteins, as well as in action potential duration and peak calcium release.

10.1039/c7cc01988b

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Citations (102)