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Biomedical subjects

G Sauer

Publications and source records attributed to G Sauer.

At least 127 records · Page 7Linked to original sources

[Ceramic bonding with alloys of non-noble metals].

The composition of the three non-precious metal alloys used in Germany was qualitatively analysed. The surface border between ceramics and metal was examined by scan electron microscope. Results showed that a gapless apposition can be established between metal and ceramic by proper preparation of the metal alloy and the ceramic mass.

Dental Alloys↗

[Molecular biology of tumor viruses].

All classes of vertebrates harbor tumor viruses that are capable of inducing either tumors or leukemias. After infection, their genomes become integral parts of the host cell's genetic material (DNA). Many biological functions such as the capacity to code for the synthesis of new proteins and, in particular, the oncogenic property (oncogen) have already been assigned to specific regions (on physical maps) of their DNA.

Animals↗

Infectious linear DNA sequences replicating in simian virus 40-infected cells.

A new class of linear duplex DNA structures that contain simian virus 40 (SV40) DNA sequences and that are replicated during productive infection of cells with SV40 is described. These structures comprise up to 35% of the radioactively labeled DNA molecules that can be isolated by selective extraction. These molecules represent a unique size class corresponding to the length of an open SV40 DNA molecule (FO III), and they contain a heterogeneous population of DNA sequences either of host or of viral origin, as shown by restriction endonuclease analysis and nucleic acid hybridization. Part of the FO III DNA molecules contain viral-host DNA sequences covalently linked with each other. They start to replicate with the onset of SV40 superhelix replication 1 day after infection. Their rate of synthesis is most pronounced 3 days after infection when superhelix replication is already declining. Furthermore, they cannot be chased into other structures. At least a fraction of these molecules is infectious when administered together with DEAE-dextran to permissive cells. After intracellular circularization, superhelical DNA FO I with an aberrant cleavage pattern accumulates. In addition, tumor and viral capsid antigen are induced, and infectious viral progeny is obtained. Infection of cells with purified SV40 FO I DNA does not result in FO III DNA molecules in the infected cells or in the viral progeny. It is suggested, therefore, that these FO III DNA molecules are perpetuated within SV40 virus pools by encapsidation into pseudovirions.

Base Sequence↗

[Homologous articular cartilage transplantation in animal experiments. Preliminary studies on sheep (author's transl)].

Homologous articular cartilage without subchondral bone instead of the usual osteochondral grafts was transplanted in sheep. The transplants were fixed to the host by a biological tissue adhesive based on fibrinogen clotting. Light- and electronmicroscopic studies showed viable transplants up to 7 months and a stable bony union with the host through endochondral bone formation. A additional external fixation of the joint after transplantation or the use of a conventional cyanoacrylate tissue adhesive failed to achieve positive results. The relations of these preliminary findings for restorative techniques of articular cartilage defects are discussed.

Animals↗

[Stress tolerance of different osteosynthetic procedures in pertrochanteric fractures (author's transl)].

To obtain valid information on stress tolerance of pertrochanteric fractures, we exposed three different methods of osteosyntheses to dynamical stress and the results were compared. The methods of osteosyntheses were application of a 130 degrees angle plate, performing an adjoining osteosynthesis with bone cement or using cephalocondylar nails. The measurements in connection with photographical and roentgenological examinations of osteosyntheses under stress gave the following results: Compared with the other methods treatment with condylar nails gave equal results in static behaviour yet was clearly superior in its dynamic reaction.

Biomechanical Phenomena↗

Random cleavage of superhelical SV 40 DNA S1 nuclease.

SV40 DNA FO I is randomly cleaved by S1 nuclease both at moderate (50 mM) and higher salt concentrations (250 mM NaC1). Full length linear S1 cleavage products of SV40 DNA when digested with various restriction endonucleases revealed fragments that were electrophoretically indistinguishable from the products found after digestion of superhelical SV40 DNA FO I with the corresponding enzyme. Concordingly, when the linear S1 generated duplexes were melted and renatured, circular duplexes were formed in addition to complex larger structures. This indicated that cleavage must have occurred at different sites. The double-strand-cleaving activity present in S1 nuclease preparations requires circular DNA as a substrate, as linear SV40 DNA is not cleaved. With regard to these properties S1 nuclease resembles some of the complex type I restriction nucleases from Escherichia coli which also cleave SV40 DNA only once, and, completely at random.

Centrifugation, Density Gradient↗