scholarly journals Initial experience with three-dimensional reconstruction of the brain using transfontanel ultrasound in infants following cardiac surgery. † 1120

1996 ◽  
Vol 39 ◽  
pp. 189-189 ◽  
Author(s):  
H Abdul-Khaliq ◽  
M Vogel ◽  
P Ewert ◽  
N Nagdyman ◽  
F Uhlemann ◽  
...  
Author(s):  
J. Frank ◽  
J. N. Turner ◽  
M. Marko ◽  
K. Asmus ◽  
D. F. Parsons

A three-dimensional reconstruction of a mitochondrion has been made based on a tilt series recorded in our HVEM. Fig. 1 is a low magnification view of an axon in cat motor cortex showing the general cellular ultrastructure and the mitochondrion used in the reconstruction. Fig. 2 shows five of the images of the mitochondrion recorded over the angular range +27° to −30°. A total of nine images were used in the reconstruction. The brain of a normal adult cat was fixed by aortic perfusion using 4% buffered paraformaldehyde with sucrose at 4°C for 15 min. The brain was then removed and fixed overnight in glut-eraldehyde. Postfixation was carried out in 1% oso4 for one hour, and the sample was then dehydrated and embedded in epon. Half micron sections were stained in aqueous uranyl acetate for two hours at 50°C followed by Reynolds lead citrate for one hour at room temperature. The tilt series was recorded in our AEI EM7 at 1.0MeV using the Swann (1) double tilt stage.


2007 ◽  
Vol 58 ◽  
pp. S184 ◽  
Author(s):  
Haruo Mizutani ◽  
Yoshihiro Takeda ◽  
Atsushi Momose ◽  
Toshihisa Takagi

Author(s):  
J. Frank ◽  
B. F. McEwen ◽  
M. Radermacher ◽  
C. L. Rieder

The tomographic reconstruction from multiple projections of cellular components, within a thick section, offers a way of visualizing and quantifying their three-dimensional (3D) structure. However, asymmetric objects require as many views from the widest tilt range as possible; otherwise the reconstruction may be uninterpretable. Even if not for geometric obstructions, the increasing pathway of electrons, as the tilt angle is increased, poses the ultimate upper limitation to the projection range. With the maximum tilt angle being fixed, the only way to improve the faithfulness of the reconstruction is by changing the mode of the tilting from single-axis to conical; a point within the object projected with a tilt angle of 60° and a full 360° azimuthal range is then reconstructed as a slightly elliptic (axis ratio 1.2 : 1) sphere.


Author(s):  
Nicolas Boisset ◽  
Jean-Christophe Taveau ◽  
Jean Lamy ◽  
Terence Wagenknecht ◽  
Michael Radermacher ◽  
...  

Hemocyanin, the respiratory pigment of the scorpion Androctonus australis is composed of 24 kidney shaped subunits. A model of architecture supported by many indirect arguments has been deduced from electron microscopy (EM) and immuno-EM. To ascertain, the disposition of the subunits within the oligomer, the 24mer was submitted to three-dimensional reconstruction by the method of single-exposure random-conical tilt series.A sample of native hemocyanin, prepared with the double layer negative staining technique, was observed by transmisson electron microscopy under low-dose conditions. Six 3D-reconstructions were carried out indenpendently from top, side and 45°views. The results are composed of solid-body surface representations, and slices extracted from the reconstruction volume.The main two characters of the molecule previously reported by Van Heel and Frank, were constantly found in the solid-body surface representations. These features are the presence of two different faces called flip and flop and a rocking of the molecule around an axis passing through diagonnally opposed hexamers. Furthermore, in the solid-body surface of the top view reconstruction, the positions and orientations of the bridges connecting the half molecules were found in excellent agreement with those predicted by the model.


Author(s):  
J.L. Carrascosa ◽  
G. Abella ◽  
S. Marco ◽  
M. Muyal ◽  
J.M. Carazo

Chaperonins are a class of proteins characterized by their role as morphogenetic factors. They trantsiently interact with the structural components of certain biological aggregates (viruses, enzymes etc), promoting their correct folding, assembly and, eventually transport. The groEL factor from E. coli is a conspicuous member of the chaperonins, as it promotes the assembly and morphogenesis of bacterial oligomers and/viral structures.We have studied groEL-like factors from two different bacteria:E. coli and B.subtilis. These factors share common morphological features , showing two different views: one is 6-fold, while the other shows 7 morphological units. There is also a correlation between the presence of a dominant 6-fold view and the fact of both bacteria been grown at low temperature (32°C), while the 7-fold is the main view at higher temperatures (42°C). As the two-dimensional projections of groEL were difficult to interprete, we studied their three-dimensional reconstruction by the random conical tilt series method from negatively stained particles.


2006 ◽  
Vol 175 (4S) ◽  
pp. 82-82
Author(s):  
Gustavo Ayala ◽  
Rile Li ◽  
Hong Oai ◽  
Mohammad Sayeeddudin ◽  
Timothy C. Thompson ◽  
...  

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