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Biomedical subjects

K Gruber

Publications and source records attributed to K Gruber.

49 records · Page 3Linked to original sources
PubMed1983

[Pharmacologic-toxicologic study of an ibuprofen-containing creme].

The antiphlogistic action, the percutaneous penetrability as well as the systemic and local tolerance of cremes with a different ibuprofen content after epicutaneous administration were examined in the rat, the guinea-pig and the rabbit. The antiphlogistic action was dose-dependently assessed on the carrageenin-induced edema of the rat paw and on UV-erythema in the guinea pig. The cotton-pellet test carried out on the rat evidenced only modest efficacy. The percutaneous penetration of ibuprofen after single epicutaneous application was obtained through the assessment of the active principle in the tissues and in the serum. The tests carried out for ascertaining the systemic and cutaneous tolerance did not evidence even after 3 to 4 weeks treatment with the ibuprofen creme any signs of intolerance due to the substance. In the investigation of the mucosal tolerance, the instillation of ibuprofen creme into the conjunctival sac of the rabbit led to strong yet reversible intolerance reactions in the conjunctiva and in the eyelid. Bearing on the results obtained on the whole, ibuprofen creme at 5% can be envisaged for clinical examination for the treatment of circumscribed rheumatic and traumatic diseases.

Administration, Topical↗
PubMedDate not supplied

Calculation of pulsatile flow and particle paths in an aneurysm-model.

The velocity field and the wall shear stress have been calculated numerically by the finite element method to the time-dependent Navier-Stokes equations for pulsatile flow in a model of an aneurysm. The results show a complex flow field with two eddies growing and disappearing during the cardiac cycle. Downstream at the outlet vessel high wall shear stress occurs, which may lead to a downstream-growing of the aneurysm. With the knowledge of a sufficiently accurate flow field, the calculation of several particle paths has been carried out. Starting points and starting time are varied. The paths demonstrate the time-dependent development, shift and disappearance of vortices during the pulsatile cycle and provide hints on zones of stasis. These are significant factors in thrombogenesis.

Aneurysm↗
PubMedDate not supplied

[Mechanics of joint stress].

The calculation of the possible load on human joints is of great importance in orthopedics. The magnitude of the force transmitted in the joints during the process of movement, whether in everyday life or in athletics, plays a decisive role. Especially at moments of impact, as in sports, high accelerations are transmitted through the human body. Bones and tissue (muscles, tendons and ligaments) react quite differently in this phase, and their reactions have a large influence on the magnitude and course of the forces working within the body, particularly in the joints. In previously developed methods of load-determination on joints during dynamic movements, these reactions were not considered. In the following paper, however, we will introduce a physical model that takes the various materials of the body's constitution into account. By introducing "wobbling mass", which, elastically damped, is coupled to the bony parts of the body, we can simulate the reaction of the body tissues, and a realistic calculation of the forces and moments transported through the body can be reached. The temporal sequence of these magnitudes for the knee and hip joints will be illustrated using an exemplary selected movement and interpreted using simplified joint structures. The main features of the method of calculation, using simple examples from statics, will be shown in Part One of this paper.

Biomechanical Phenomena↗
PubMedDate not supplied

[Biomechanical analysis of locomotion patterns in the lower limb. II. Forces in joints].

After the introduction of a tri-sectional schematic model of the human body it was possible to investigate the simple dynamic locomotion pattern (braking process after a free fall); from this, the effective weight force and the ground recoil forces could be calculated. Once the external forces and the locomotion pattern are known the forces in the knee and hip joint can be determined with simplified joint structures, both for static bending of the knee as well as for the braking process during locomotion. This general calculation of internal forces is performed according to the so-called cross-section principle, since even this permits a basic comparison to be made between the forces acting at rest and during movement. The calculations show that during movement there is a relatively slight increase in the forces in the hip joint; on the other hand, following a free fall from 1.5 m and up to a kneebending angle of 100 degrees, the bearing force in the knee joint during braking increases to 21 times body weight. Thus, there is a massive increase in the internal forces during movement owing to the need for transmission of torque. Conclusions can be drawn from this concerning the development o much greater than f gonarthrosis in cases where there has been relatively little previous damage (for example), recurrent effusions, slight defects of the leg axes, slight instabilities of capsular ligaments).

Biomechanical Phenomena↗
PubMedDate not supplied

[Biomechanical analysis of locomotion patterns of the lower extremity. I. Acceleration].

Starting with his own biostatic analysis of strains and stresses affecting the human hip joint the author here extends his observations to include movement. Since the acceleration rates of individual parts of the body have to be known to calculate internal joint forces, calculations done a realistic three-limbed model are described. The braking process following a free fall from a height of 1.5 m is analyzed as a simple locomotion pattern and the calculated acceleration rates are compared with measurements published in the literature. With the model presented here locomotion patterns can be described very well and quantitatively recorded.

Acceleration↗
PubMedDate not supplied

Atomic resolution crystal structure of hydroxynitrile lyase from Hevea brasiliensis.

The X-ray crystal structure of native hydroxynitrile lyase from Hevea brasiliensis (Hb-HNL) has been determined at 1.1 A resolution. It refined to a final R of 11.5% for all data and an Rfree of 14.4%. The favorable data-to-parameter ratio at atomic resolution made the refinement of individual anisotropic displacement parameters possible. The data also allowed a clear distinction of the alternate orientations of all histidine and the majority of asparagine and glutamine side chains. A number of hydrogen atoms, including one on the imidazole of the mechanistically important His-235, became visible as peaks in a difference electron density map. The structure revealed a discretely disordered sidechain of Ser-80, which is part of the putative catalytic triad. Analysis of the anisotropy indicated an increased mobility of residues near the entrance to the active site and within the active site.

Aldehyde-Lyases↗