The Elastic Properties of Arteries in Relation to the Physiological Functions of the Arterial System

The remarkable deformability of the erythrocyte derives in large part from the elastic properties of spectrin, the major component of the membrane skeleton. It is generally accepted that spectrin's elasticity arises from marked conformational changes which include variations in its overall length (1). In this work the structure of spectrin in partially expanded membrane skeletons was studied by electron microscopy to determine the molecular basis for spectrin's elastic properties. Spectrin molecules were analysed with respect to three features: length, conformation, and quaternary structure. The results of these studies lead to a model of how spectrin mediates the elastic deformation of the erythrocyte.Membrane skeletons were isolated from erythrocyte membrane ghosts, negatively stained, and examined by transmission electron microscopy (2). Particle lengths and end-to-end distances were measured from enlarged prints using the computer program MACMEASURE. Spectrin conformation (straightness) was assessed by calculating the particles’ correlation length by iterative approximation (3). Digitised spectrin images were correlation averaged or Fourier filtered to improve their signal-to-noise ratios. Three-dimensional reconstructions were performed using a suite of programs which were based on the filtered back-projection algorithm and executed on a cluster of Microvax 3200 workstations (4).

Download Full-text

The buckling of thin EM specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177386 ◽

1990 ◽

Vol 48 (4) ◽

pp. 850-851

Author(s):

A.R. Thölén

Keyword(s):

Electron Microscope ◽

Elastic Properties ◽

Crystal Surface ◽

Specimen Surface ◽

Radius Of Curvature ◽

Thin Foils ◽

Thin Electron ◽

Regular Patterns

Thin electron microscope specimens often contain irregular bend contours (Figs. 1-3). Very regular bend patterns have, however, been observed around holes in some ion-milled specimens. The purpose of this investigation is twofold. Firstly, to find the geometry of bent specimens and the elastic properties of extremely thin foils and secondly, to obtain more information about the background to the observed regular patterns.The specimen surface is described by z = f(x,y,p), where p is a parameter, eg. the radius of curvature of a sphere. The beam is entering along the z—direction, which coincides with the foil normal, FN, of the undisturbed crystal surface (z = 0). We have here used FN = [001]. Furthermore some low indexed reflections are chosen around the pole FN and in our fcc crystal the following g-vectors are selected:

Download Full-text

Condition of the cerebral arterial system in the patients with low radiation doses: duplex scans investigation V.G. Leliuk, A.K. Guskova, S.E. Leliuk. SRC, Institute of Biophysics, Moscow, Russia

European Journal of Ultrasound ◽

10.1016/s0929-8266(97)90046-x ◽

1997 ◽

Vol 5 ◽

pp. 18-19

Keyword(s):

Arterial System ◽

Radiation Doses ◽

Low Radiation Doses

Download Full-text

Changes in water relations and in some physiological functions of bean under very light osmotic shock induced by polyethylene glycol

Physiologia Plantarum ◽

10.1034/j.1399-3054.1992.840407.x ◽

1992 ◽

Vol 84 (4) ◽

pp. 537-548

Author(s):

Vittorio Raggi

Keyword(s):

Polyethylene Glycol ◽

Water Relations ◽

Osmotic Shock ◽

Physiological Functions

Download Full-text

The Hydrostatic Pressure Effect on Elastic Properties of B2-Phase Single Crystals Ti50Ni48Fe2and Ti50Ni45Fe5Alloys

Journal de Physique IV (Proceedings) ◽

10.1051/jp4/199558729 ◽

1995 ◽

Vol 05 (C8) ◽

pp. C8-729-C8-734

Author(s):

A.I. Lotkov ◽

V.P. Lapshin ◽

V.A. Goncharova ◽

H.V Chernysheva ◽

V.N. Grishkov ◽

...

Keyword(s):

Hydrostatic Pressure ◽

Single Crystals ◽

Elastic Properties ◽

Pressure Effect ◽

B2 Phase

Download Full-text

Plasma Levels of Lipoprotein(a) Are Elevated in Patients with the Antiphospholipid Antibody Syndrome

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642454 ◽

1994 ◽

Vol 71 (04) ◽

pp. 424-427 ◽

Cited By ~ 42

Author(s):

Masahide Yamazaki ◽

Hidesaku Asakura ◽

Hiroshi Jokaji ◽

Masanori Saito ◽

Chika Uotani ◽

...

Keyword(s):

Plasma Levels ◽

Active Form ◽

Plasminogen Activator Inhibitor ◽

Arterial System ◽

Control Group ◽

Antiphospholipid Antibody ◽

Antiphospholipid Antibody Syndrome ◽

Lipoprotein A ◽

Soluble Thrombomodulin ◽

Relationship Of

SummaryThe mechanisms underlying clinical abnormalities associated with the antiphospholipid antibody syndrome (APAS) have not been elucidated. We measured plasma levels of lipoprotein(a) [Lp(a)], the active form of plasminogen activator inhibitor (active PAI), thrombin-antithrombin III complex (TAT) and soluble thrombomodulin (TM), to investigate the relationship of these factors to thrombotic events in APAS. Mean plasma levels of Lp(a), TAT, active PAI and TM were all significantly higher in patients with aPL than in a control group of subjects. Plasma levels of Lp(a) and active PAI were significantly higher in patients with aPL and arterial thromboses than in patients with aPL but only venous thromboses. There was a significant correlation between plasma levels of Lp(a) and active PAI in patients with aPL. These findings suggest that patients with aPL are in hypercoagulable state. High levels of Lp(a) in plasma may impair the fibrinolytic system resulting in thromboses, especially in the arterial system.

Download Full-text