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Biomedical subjects

A Schroeder

Publications and source records attributed to A Schroeder.

At least 91 records · Page 5Linked to original sources
PubMed1978

[The accumulation of osteocementum around a dental implant under physical loading].

Hollow cylinder implants of titanium with a titanium spray surface were implanted in macaca speciosa, as previously described (Schweiz.Mschr.Zahnheilk.86: 713, 1976). This time, however, the implants were submitted to masticatory forces. Histologically it can be shown that the ankylotic contact between implant and bone, which is initially obtained, remains after 6-16 months. In one case the substance encasing the implant at its deepest part was identified as genuine osteocementum.

Animals↗
PubMed1978

[Pulp protection].

Explore the source record for details and available documents.

Dental Cavity Lining↗
PubMed1977

[Relativity and limits of success yesterday and today].

A comparing of today's dentistry and the time limits of its success with dental medecine of yesterday, we state an unquestionable advance in the preventive field. Causes of caries and parodontopathies are so well known that proper preventive measures have shown, within the last twenty years, statistically relevant success. Such positive results may be endangered by politics which tend to eliminate personal responsibility and which establish insurance systems by which even the most expensive dental restorations must be paid by the collective community. Thus prophylactic measures become unimportant to the individual. Preventive thinking has various facets: The system of filling gaps and holes must yield to the system of rehabilitation at every level. The basis to this is a high standard of professional ethics. Its realization is easier if dentistry is not subdivided into too many specialties. On the other hand, the dentist must have a large spectrum of knowledge, which is only obtainable through continuous education. The younger generations are profiting most from this development of knowledge, but the old and the handicapped should not be forgotten in the process. It will be one of the noblest tasks of the profession henceforward to care for the treatment of this dentally underpriviledged part of our population.

Dental Prophylaxis↗
PubMed1976

[Tissue reaction to an implant of a titanium hollow cylinder with a titanium surface spray layer].

A new implant consisting of a hollow cylinder of titanium is described. It is well suited to investigate the tissue reaction to several surface textures in the animal experiment (Macaca speciosa). From a test series, for which the implants were surfaced with powdered titan (titan plasma), one was selected which had been worn for 7 months as a partial support. The solid incorporation observed radiologically presents itself, light microscopically, as an immediate growing in of the bone into the rough implant surface. There is no evidence of the formation of a soft tissue bed. Electron microscope pictures reveal that the bone closely anchored to the titan plasma surface.

Animals↗
PubMed1975

Genetic control of radiation sensitivity and DNA repair in Neurospora.

Radiation sensitivity in the fungus Neurospora crassa is under the control of at least eight distinct loci and is also affected by cytoplasmic factors. Although radiation-sensitive mutants which affect inter- or intragenic meiotic recombination have not been isolated, mutants which are defective in the repair of pyrimidine dimers have been found. Evidence from both mutational and biochemical studies shows that Neurospora has an excision-repair system for pyrimidine dimers which is very similar to the one found in Escherichia coli. Wild-type strains excise dimers, but two mutants, uvs2 and upr1, are UV sensitive and excision defective. Like the E. coli excision-defective mutants, the Neurospora mutants show a greatly increased frequency of UV-induced mutation at low UV doses, and they do not affect recombination. However, they differ from the E. coli mutants in being significantly more sensitive to ionizing radiation than wild-type strains. A third mutant, uvs6, resembles the DNA polymerase-I-negative mutants of E. coli. It is sensitive to both UV and X-irradiation, has a wild-type pattern of UV-induced mutation, and increases spontaneous deletion frequencies. Its polymerases have not been examined. The high frequency of UV-induced mutation in excision-defective strains suggests that a "mutation prone" system of DNA repair exists in Neurospora. This is supported by the ppoperties of the uvs3 strain, which shows no UV-induced mutation. Like postreplication-repair-defective E. coli mutants, it is UV and ionizing radiation sensitive and sensitive to both monofunctional and bifunctional alkylating agents. This mutant is sterile. As expected, the double mutant uvs3 upr1 strain is much more sensitive to UV than either single-mutant strain. Two other loci, muc2 and gs6, may affect DNA repair. Mutations at the five remaining loci, uvs1, uvs4, uvs5, gs3, and gs20, lead to a constellation of properties unlike those of any DNA-repair-deficient E. coli mutant. The occurrence of these mutations could mean that other DNA repair systems exist in Neurospora, or, like the lon mutants of E. coli, they might indicate that cell sensitivity to radiation damage can be increases in other ways.

DNA↗