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Biomedical subjects

A Schroeder

Publications and source records attributed to A Schroeder.

At least 73 records · Page 4Linked to original sources
PubMed1981

The reactions of bone, connective tissue, and epithelium to endosteal implants with titanium-sprayed surfaces.

The results of a research project which has been under way for the last 7 years are reported. The project has been centred around a series of animal (monkey) experiments designed to test the suitability of cylindrical titanium implants with titanium-sprayed surfaces. The following results have been obtained: 1. The bone applies itself "ankylotically" (i.e. without an intervening layer of connective tissue) to the surface of the implant and, as revealed by observation over periods of up to 1 3/4 years, even remains attached to the implant surface when placed under load. 2. The fibres of the connective tissue between the bone and the epithelium insert into the titanium-sprayed surface and appear to be functionally orientated. 3. If the post of the implant is situated in a region of immobile, keratinized mucosa signs of adhesion of the epithelial cells to the titanium-sprayed surface become apparent. 4. The clinical success of the implant is clearly dependent on (a) the presence of tethered, immobile mucosa ("gingiva") around the post of the implant, and (b) perfect oral hygiene.

Animals↗
PubMed1981

Biological and biochemical effects of 2'-azido-2'-deoxyarabinofuranosylcytosine on human tumor cells in vitro.

2-azido-2'-deoxyarabinofuranosylcytosine (Cytarazid), recently synthesized, was found to inhibit the in vitro growth of several human cell lines by 50% at concentrations ranging from 0.06 to 0.2 microM and to prevent the replication of herpes simplex virus types 1 and 2 by 98% at 50 microM. As determined with HeLa cells, the inhibition of cell growth was partially prevented by 2'-deoxycytidine (dCyd) and cytidine but not by uridine or thymidine. Cytarazid proved resistant to deamination by human cytidine/dCyd deaminases purified from acute myelocytic leukemia blast cells and from liver, a property reflected in the inability of tetrahydrouridine to enhance the cytotoxicity of the compound. Cytarazid served as a substrate for cytoplasmic dCyd kinase partially purified from human peripheral chronic lymphocytic leukemia blast cells. At a concentration of 0.4 mM, the nucleoside analog was phosphorylated 2.6 times more effectively by this enzyme than was dCyd, the Km for Cytarazid being 250 microM. In intact HeLa cells, the triphosphate derivative of Cytarazid was the major drug metabolite formed. In these cells, the analog interfered with the incorporation of radiolabeled thymidine into DNA at a concentration and a time interval at which the incorporation of uridine into RNA and amino acids into protein was not inhibited, suggesting that interference with DNA synthesis is a primary drug effect. Further analysis showed that Cytarazid triphosphate interferes with DNA synthesis in intact HeLa cell nuclei and that it inhibits both the alpha- and beta-DNA polymerases purified from HeLa cells in a manner competitive with deoxycytidine triphosphate, with Ki's of 0.6 and 0.7 microM, respectively. Cytarazid triphosphate was not able to replace deoxycytidine triphosphate for the synthesis of DNA in either intact nuclei or in cell-free preparations; but, in the cell-free assay system, the compound was found to interfere with primer-template activity.

Biotransformation↗
PubMed1980

[Dentistry: debit and credit; the 1979 rectorial address in Bern].

The importance of the elimination of pain and its refinement by local anesthesia, analgesia and general anesthesia is shown in dental treatment. Preventive measures have gained weight: Teaching patients about plaque and sugar, the importance of fluorides, oral hygiene in school dentistry, changes in nutrition. Economic aspects are shown in the divergence of cost between prevention and therapy. Implants as a last resource are mentioned. Finally, in conclusion, it is emphasized that prevention must rank first in proper dental education into which postgraduate education in a future postgraduate clinic should be integrated.

Anesthesia, Dental↗