Symmetry breaking in molecular calculations and the reliable prediction of equilibrium geometries. The formyloxyl radical as an example

1985 ◽  
Vol 83 (7) ◽  
pp. 3567-3576 ◽  
Author(s):  
A. D. McLean ◽  
B. H. Lengsfield ◽  
J. Pacansky ◽  
Y. Ellinger
Keyword(s):  
Symmetry Breaking ◽  
Reliable Prediction ◽  
Molecular Calculations ◽  
Equilibrium Geometries

Symmetry breaking in convergent-beam diffraction

1989 ◽  
Vol 47 ◽  
pp. 480-481
Author(s):  
D.J. Eaglesham
Keyword(s):  
Symmetry Breaking ◽  
Point Group ◽  
X Ray Diffraction ◽  
Multiple Diffraction ◽  
Space Groups ◽  
Atomic Displacements ◽  
Small Probe ◽  
Phase Sensitive ◽  
Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

2020 ◽  
Vol 48 (3) ◽  
pp. 1243-1253 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Cell Cortex ◽  
Axis Formation ◽  
Aurora A Kinase ◽  
Aurora A ◽  
C Elegans ◽  
Cell Embryo ◽  
Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

A Symmetry-Breaking Theory of False Pop Out

2011 ◽  
Author(s):  
Kimberley D. Orsten ◽  
Mary C. Portillo ◽  
James R. Pomerantz
Keyword(s):  
Symmetry Breaking

Lessons learned from the optimization of natural product based kinase inhibitors through molecular calculations

Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
V Myrianthopoulos ◽  
P Magiatis ◽  
AL Skaltsounis ◽  
L Meijer ◽  
E Mikros
Keyword(s):  
Natural Product ◽  
Kinase Inhibitors ◽  
Lessons Learned ◽  
Molecular Calculations

Dosimetry with 188Re-labelled monoclonal anti-CD66 antibodies

2006 ◽  
Vol 45 (03) ◽  
pp. 134-138 ◽  
Author(s):  
T. Kull ◽  
N. M. Blumstein ◽  
D. Bunjes ◽  
B. Neumaier ◽  
A. K. Buck ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Gamma Camera ◽  
Absorbed Dose ◽  
Correlation Coefficients ◽  
Residence Times ◽  
Reliable Prediction ◽  
Red Bone Marrow ◽  
Antibody Preparation ◽  
Simplified Method

SummaryAim: For the therapeutic application of radiopharmaceuticals the activity is determined on an individual basis. Here we investigated the accuracy for a simplified assessment of the residence times for a 188Re-labelled anti-CD66 monoclonal antibody. Patients, methods: For 49 patients with high risk leukaemia (24 men, 25 women, age: 44 ± 12 years) the residence times were determined for the injected 188Re-labelled anti-CD66 antibodies (1.3 ± 0.4 GBq, 5–7 GBq/mg protein, >95% 188Re bound to the antibody) based on 5 measurements (1.5, 3, 20, 26, and 44 h p.i.) using planar conjugate view gamma camera images (complete method). In a simplified method the residence times were calculated based on a single measurement 3 h p.i. Results: The residence times for kidneys, liver, red bone marrow, spleen and remainder of body for the complete method were 0.4 ± 0.2 h, 1.9 ± 0.8 h, 7.8 ± 2.1 h, 0.6 ± 0.3 h and 8.6 ± 2.1 h, respectively. For all organs a linear correlation exists between the residence times of the complete method and the simplified method with the slopes (correlation coefficients R > 0.89) of 0.89, 0.99, 1.23, 1.13 and 1.09 for kidneys, liver, red bone marrow, spleen and remainder of body, respectively. Conclusion: The proposed approach allows reliable prediction of biokinetics of 188Re-labelled anti-CD66 monoclonal antibody biodistribution with a single study. Efficient pretherapeutic estimation of organ absorbed dose may be possible, provided that a more stable anti-CD66 antibody preparation is available.

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