Biomedical subjects

R Wittenberg

Publications and source records attributed to R Wittenberg.

6 recordsLinked to original sources

PubMed2000

The "resin-capture-release" hybrid technique: a merger between solid- and solution-phase synthesis.

A polymer-assisted organic synthesis that combines the concept of solid-phase synthesis with the idea of polymer-supported scavenging reagents has recently appeared on the chemistry scene. This technique has frequently been termed the "resin-capture-release" methodology and is initiated by the immobilization of a small molecule on a polymeric support. This intermediate is subjected to a second transformation by adding a new reaction partner in solution. This reactant plays two roles: a) the chemical alteration of the polymer-bound intermediate and b) the simultaneous release of this reaction product from the resin back into solution. This new concept is presented and future prospects are discussed.

Journal Article↗

PubMed1997

Electron transfer proteins from the haloalkaliphilic archaeon Natronobacterium pharaonis: possible components of the respiratory chain include cytochrome bc and a terminal oxidase cytochrome ba3.

Natronobacterium pharaonis, an aerobic haloalkaliphilic archaebacterium, expresses high concentrations of redox proteins as do alkaliphilic eubacteria. The first redox protein characterized from N. pharaonis was halocyanin [Scharf, B., & Engelhard, M. (1993) Biochemistry 32, 12894-12900], a small blue copper protein. It is a peripheral membrane protein and is conjectured to function in a manner similar to plastocyanin. In the present work, the respiratory chain is further elucidated and the purification and characterization of the most abundant components cytochrome bc and cytochrome ba3 from the membrane fraction are described. The cytochrome bc complex consists of a 14 and an 18 kDa subunit in a 1:1 ratio, with heme c bound to the larger polypeptide. An Fe-S subunit similar to that found in eukaryotic bc complexes has not yet been identified. The second membrane complex carries two different heme groups of the ba3-type as well as copper. It contains two subunits of 36 and 40 kDa. This cytochrome ba3 binds carbon monoxide, a feature common to terminal oxidases. There is no spectroscopic evidence for a second terminal oxidase; hence, under the growth conditions chosen the respiratory chain of N. pharaonis appears to be unbranched. In addition to these cytochromes, a succinate dehydrogenase which is solubilized from the membrane by detergents was isolated. A cytochrome c which was isolated from the cytosol has an unusually high molecular weight and a redox potential of -142 mV. A second cytosolic protein, ferredoxin, was purified to homogeneity. A comparison of the redox potentials of the isolated proteins with those obtained from the native membrane allows the construction of a possible electron transfer chain.

Bacterial Outer Membrane Proteins↗

PubMed1992

[Ultrasonic velocity measurements at weight-bearing and non-weight-bearing sites of the peripheral skeleton. The effect of physical activity in soccer players].

Ultrasound transmission velocity at the appendicular skeleton is determined by elastic properties of the bone as mass density. We evaluated ultrasound transmission velocity at the os calcis of both feet and at the proximal phalanges of DII and DIII of both hands in 51 male subjects. 28 of them were professional soccer players of the 1st German division, 11 subjects performed non-professional exercise in various athletic organisations regularly and 12 did not exercise at all. A significant difference in the speed of sound could be seen at os calcis, where the soccer players had higher velocities than the other groups. The differences between the groups at the upper and lower extremities suggest that changes in ultrasound transmission velocity are not only affected by structural changes in the aging skeleton, as it might be suggested by age differences, but by exercise. Physical exercise can change the properties (structure and/or density) of weightbearing bone and this can be detected by measuring ultrasound velocity.

Adolescent↗

PubMed1980

Aspects of the creative process in music: a case report.

A gifted patient, hampered by his ambivalent strivings, began to write music during his analysis and became a professional composer. I have attempted to show a parallel between the analytic and the creative process. Both in his use of dreams and his particular style of free association, the original idea appeared in fully developed form, marked by key themes. As his ambivalent strivings were analyzed, his narcissistic libido was used less and less as a substitute for ego-strivings, but, instead, as countercathexis. With the freeing of ego functioning, the patient appeared to concentrate on working through, which parallels the development section in music and seems to contain one of the significant aspects of the creative process.

Adult↗

PubMedDate not supplied

[Biomechanical study on lumbar spondylodeses using an internal fixateur consisting of a titanium alloy].

OBJECTIVE: Biomechanical properties of an internal fixateur manufactured of a titanium alloy (Ti-6Al-4V-alloy) to be evaluated in an in vitro setting. METHOD: Internal fixateurs were inserted into six (four female and two male specimens) human lumar spine segments L2 to L4. Only dorsal instrumentations were performed. Physiological loads were applied (2.0 to 10.0 Nm for torque, 2.0 to 7.5 Nm for extension/flexion and lateral bending). Biomechanical investigations were performed in four settings: Intact specimen without instrumentation, instrumented specimen, instrumented specimen after corpectomy of the middle vertebral body, instrumented specimen after corpectomy of the middle vertebral body with an additional transverse connector. RESULTS: Stability after instrumentation was increased by 84.7 % for flexion/extension, by 78.2 % for lateral bending and by 43 % for axial torsion. Axial torsion was already less distinct in the physiological specimen. The stability of instrumented specimen after corpectomy was superior to that of intact vertebral segments without internal fixation. Additional application of transverse connectors did not significantly enhance the stiffness of the implant. CONCLUSION: For the clinical use there is no difference in the biomechanical properties of the titanium fixateur compared to similar constructions made of stainless steel. The possibility of performing MRI- or CT-scans after implantation of titanium implants is a main clinical advantage. The stabilisation after corpectomy is remarkable, so that a sufficient fracture-stabilisation is possible. Based on the data, the application of transverse connectors cannot be recommended.

Adult↗

PubMedDate not supplied

[Attitudes to automobile ownership and feelings of insecurity of the elderly in traffic].

The results of a trend analysis concerning the traffic involvement of older people between 1975 and 1984 demonstrate that this group shows very positive attitudes towards motor-car ownership, with regard to the instrumental functions of motor-cars as well as to their non-instrumental values. However, attitudes toward motor-cars vary considerably within this population. The heterogeneity of the group of older people is also demonstrated with regard to their feelings of anxiety in traffic situations. The accumulation of some negative individual and collective variables results in increasing anxiety and immobility. As the results show, these feelings of anxiety are gradually increasing since 1975.

Accidents, Traffic↗