Multi-scale approaches for the simulation of cardiac electrophysiology: II – Tissue-level structure and function

The learning objectives of this chapter are to review some basic electrophysiologic concepts that are useful for the clinician. These include 1) the structure and function of cardiac ion channels; 2) the role of ion channels in the generation of cardiac action potentials; 3) the mechanisms of cardiac arrhythmias; and 4) inherited and acquired channelopathies.

Download Full-text

Multi-scale coding of genomic information: From DNA sequence to genome structure and function

Physics Reports ◽

10.1016/j.physrep.2010.10.001 ◽

2011 ◽

Vol 498 (2-3) ◽

pp. 45-188 ◽

Cited By ~ 93

Author(s):

Alain Arneodo ◽

Cédric Vaillant ◽

Benjamin Audit ◽

Françoise Argoul ◽

Yves d’Aubenton-Carafa ◽

...

Keyword(s):

Dna Sequence ◽

Genome Structure ◽

Structure And Function ◽

Genomic Information ◽

Multi Scale ◽

And Function

Download Full-text

Biogeomes of hydrosphere and land as elements of the biosphere structure

Ecology and Noospherology ◽

10.15421/031601 ◽

2015 ◽

Vol 27 (1-2) ◽

pp. 5-15

Author(s):

A. A. Protasov

Keyword(s):

Abiotic Factors ◽

Level Structure ◽

Structure And Function ◽

Woody Vegetation ◽

Strong Impact ◽

Ecosystem Level ◽

And Function ◽

Natural Groups ◽

Ecological Convergence

Ecosystems as the smallest unit in the structure of the biosphere form natural groups with similar nonliving or inert components (geome) and leaving, biotic (biome) as a result of the ecological convergence. Thus it is formed following after ecosystem level structure of the biosphere – biogeomes or complexes of similar in its structure and function ecosystems. It is proposed unit classification of 12 biogeomes of hydrosphere and land, combining with three types of ecosystems: biotic, oligobiotic and subbiotic types. The biotic type combine with ecosystems controlled by leaving components as well as woody vegetation or hermatypic corrals. The ecosystems of oligobiotic type have strong impact of abiotic factors but biotic ones are important too. It is grass ecosystems on the land, and shelf ecosystems of ocean. In subbiotic type of ecosystems strongly prevail in its habitus abiotic components. It is ecosystems of deserts, and ocean deep bottom or pelagic ocean ecosystems. The evolution of biosphere was lead as well as to new local ecosystems divergently and convergently to formation limit number of ecosystems types, biogeomes. There is reason to believe it possible to form a new scientific section – biogeomics because there is a particular object of it study – the biogeome.

Download Full-text

Mechanical Regulation of Cells by Materials and Tissues

MRS Bulletin ◽

10.1557/mrs2010.525 ◽

2010 ◽

Vol 35 (8) ◽

pp. 578-583 ◽

Cited By ~ 32

Author(s):

Wendy E. Thomas ◽

Dennis E. Discher ◽

V. Prasad Shastri

Keyword(s):

Cell Fate ◽

Single Molecule ◽

Control Cell ◽

Tissue Level ◽

Structure And Function ◽

Mechanical Forces ◽

Single Molecule Level ◽

Biophysical Studies ◽

And Function ◽

Insight Into

AbstractOver the last dozen years, studies at the cell and tissue level have demonstrated that the function and fate of all cells, stem cells in particular, are affected by the collective physical properties of their microenvironments. Meanwhile, biophysical studies at the single molecule level have taught us a great deal about how mechanical forces affect the structure and function of proteins involved in the assembly of cells into tissues. Together, these molecular, cellular, and tissue studies provide insight into the process and importance of mechanotransduction, which is the process by which mechanical forces are transduced into biological signals. This insight should motivate biomimetic approaches to better control cell fate and tissue function.

Download Full-text

Structure and function of neural networks in the retina

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102213 ◽

1988 ◽

Vol 46 ◽

pp. 26-27

Author(s):

Peter Sterling

Keyword(s):

Ganglion Cells ◽

Three Dimensional ◽

Structure And Function ◽

Synaptic Connections ◽

Visual Axis ◽

One Dimensional ◽

Cat Retina ◽

Ultrathin Sections ◽

And Function ◽

Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Download Full-text

Osseointegration interface of calcified bone and endosseous implants

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130110 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1096-1097

Author(s):

K.E. Krizan ◽

J.E. Laffoon ◽

M.J. Buckley

Keyword(s):

Structure And Function ◽

Titanium Implants ◽

En Bloc ◽

Endosseous Implants ◽

Ultrastructural Studies ◽

The Past ◽

Cacodylate Buffer ◽

One Year ◽

And Function

With increase use of tissue-integrated prostheses in recent years it is a goal to understand what is happening at the interface between haversion bone and bulk metal. This study uses electron microscopy (EM) techniques to establish parameters for osseointegration (structure and function between bone and nonload-carrying implants) in an animal model. In the past the interface has been evaluated extensively with light microscopy methods. Today researchers are using the EM for ultrastructural studies of the bone tissue and implant responses to an in vivo environment. Under general anesthesia nine adult mongrel dogs received three Brånemark (Nobelpharma) 3.75 × 7 mm titanium implants surgical placed in their left zygomatic arch. After a one year healing period the animals were injected with a routine bone marker (oxytetracycline), euthanized and perfused via aortic cannulation with 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.2. Implants were retrieved en bloc, harvest radiographs made (Fig. 1), and routinely embedded in plastic. Tissue and implants were cut into 300 micron thick wafers, longitudinally to the implant with an Isomet saw and diamond wafering blade [Beuhler] until the center of the implant was reached.

Download Full-text

Use of human autoantibodies and immunoelectron microscopy to study structure and function of the nucleolus and nuclear bodies

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122939 ◽

1992 ◽

Vol 50 (1) ◽

pp. 506-507

Author(s):

Robert L. Ochs

Keyword(s):

Electron Microscopy ◽

Structure And Function ◽

Nuclear Bodies ◽

Nuclear Interior ◽

Coiled Bodies ◽

Interchromatin Granules ◽

And Function ◽

Conventional Electron Microscopy ◽

Perichromatin Granules ◽

Perichromatin Fibrils

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

Download Full-text

Depletion and Reconstitution of Active E. Coli Ribosomes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100116826 ◽

1975 ◽

Vol 33 ◽

pp. 640-641

Author(s):

M. Boublik ◽

W. Hellmann ◽

F. Jenkins

Keyword(s):

Protein Biosynthesis ◽

Large Subunit ◽

High Resolution Electron Microscopy ◽

Small Subunit ◽

Structure And Function ◽

Biologically Active ◽

Biological Macromolecules ◽

E Coli ◽

Resolution Electron ◽

And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

Download Full-text