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Biomedical subjects

H Thiele

Publications and source records attributed to H Thiele.

131 records · Page 8Linked to original sources
PubMedDate not supplied

[Numerical simulation (FEM) of the human mandible: validation of the function of the masticatory muscles].

The article describes part of a research project aiming to develop a new modular software tool for the individual dynamic numerical simulation of the human mandible using the finite element method (FEM). Its planned use in the clinical setting makes it very important to validate the results of the simulations. Here, the function of the masticatory muscles is to be tested. On the basis of biomechanical data from the literature, standard movements, such as closing the mouth, forward movement, lateral movement or backward movement, were dynamically simulated. Apart from muscle activity, the movements of the mandible are defined by the temporomandibular joint. At present, translating the condylar dynamics to the simulation still poses problems. For this reason, therefore, simulations of the two extreme cases "fixed" and "force-free" condyles are compared. While in the case of fixed condyles, some of the movements could be reproduced either not at all or only weakly, in the case of force-free condyles, all standard movements were reproduced qualitatively, albeit without the guiding effect of the joint capsule or the articular disc.

Biomechanical Phenomena↗
PubMedDate not supplied

Calculation of the circular dichroism of Chironomus hemoglobin in the light of the quality of its X-ray structure.

For the larval hemoglobin III of the insect Chironomus thummi thummi, the rotational strength of the B (Soret) and Q band is calculated with a monopole/monopole and a dipole/dipole approximation applied to the atomic co-ordinates of the X-ray structures at 2.5 and 1.4 A resolution. In previous calculations using the 2.5 A co-ordinates and with perturbing groups being restricted to aromatic side-chains, the dipole/dipole approximation clearly confirmed the negative sign observed by experiment. The predominant interactions were those of phenylalanine residues. Recalculation with X-ray data refined to the present limits of performance corroborates the negativity of the rotational strength, but now the most important contributions are due to the peptide bonds formerly neglected. Also for the 2.5 A coordinates it is learned that in contrast to earlier expectation the influence of the backbone in this hemoglobin is rather strong. A substantial contribution is further obtained for the perturbation by one of the propionic acid carboxylate groups of the heme. Perspectives and problems of the approach are outlined.

Amino Acids↗