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The vertebrate skeletal muscle thick filaments are not three-stranded. Reinterpretation of some experimental data*

100%
Skubiszak L., Kowalczyk L.
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2002
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vol. 49
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issue 4
841-853
EN
Computer simulation of mass distribution within the model and Fourier transforms of images depicting mass distribution are explored for verification of two alternative modes of the myosin molecule arrangement within the vertebrate skeletal muscle thick filaments. The model well depicting the complete bipolar structure of the thick filament and revealing a true threefold-rotational symmetry is a tube covered by two helices with a pitch of 2 × 43 nm due to arrangement of the myosin tails along a helical path and grouping of all myosin heads in the crowns rotated by 240° and each containing three cross-bridges separated by 0°, 120°, and 180°. The cross-bridge crown parameters are verified by EM images as well as by optical and low-angle X-ray diffraction patterns found in the literature. The myosin tail arrangement, at which the C-terminus of about 43-nm length is near-parallel to the filament axis and the rest of the tail is quite strongly twisted around, is verified by the high-angle X-ray diffraction patterns. A consequence of the new packing is a new way of movement of the myosin cross-bridges, namely, not by bending in the hinge domains, but by unwrapping from the thick filament surface towards the thin filaments along a helical path.
2
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Myosin molecule packing within the vertebrate skeletal muscle thick filaments. A complete bipolar model*

100%
Skubiszak L., Kowalczyk L.
|
EN
Computer modelling related to the real dimensions of both the whole filament and the myosin molecule subfragments has revealed two alternative modes for myosin molecule packing which lead to the head disposition similar to that observed by EM on the surface of the cross-bridge zone of the relaxed vertebrate skeletal muscle thick filaments. One of the modes has been known for three decades and is usually incorporated into the so-called three-stranded model. The new mode differs from the former one in two aspects: (1) myosin heads are grouped into asymmetrical cross-bridge crowns instead of symmetrical ones; (2) not the whole myosin tail, but only a 43-nm C-terminus of each of them is straightened and near-parallel to the filament axis, the rest of the tail is twisted. Concurrent exploration of these alternative modes has revealed their influence on the filament features. The parameter values for the filament models as well as for the building units depicting the myosin molecule subfragments are verified by experimental data found in the literature. On the basis of the new mode for myosin molecule packing a complete bipolar structure of the thick filament is created.
3
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The Procedure for SPECT and BEAM Images Adjustment Visualisation of EEG Electrodes in SPECT Images

52%
Goszczyńska H., Królicki L., Bajera A., Zalewska E., Kowalczyk L., Walerjan P., Rysz A., Kolebska K.
Polish Journal of Medical Physics And Engineering
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2007
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vol. 13
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issue 3
115-125
EN
Preliminary results of research to devise a method allowing spatial alignment of BEAM maps obtained from EEG examinations with SPECT data are presented. The main concept of the method presented lies in simultaneous recording of multi-channel EEGs during SPECT examination, and also in visualizing location of EEG electrodes on SPECT images that provide spatial three dimensional coordinates assignment. The proposed methodology of simultaneous SPECT and EEG examinations could be a significant complement to results of epileptic focus localisation obtained with the ISAS method used for the last few years. The ISAS method allows localisation of focuses with 80% confidence, but it requires carrying out MRI examinations for alignment of compared anatomical structures on two SPECT images. Complementing these results with a BEAM map analysis would improve significantly the effectiveness of the examinations. This work presents results of experiments carried out on the Jaszczak phantom.
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