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Biomedical subjects

W Bauer

Publications and source records attributed to W Bauer.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Space closure with T loops (Burstone)--a clinical study].

The theoretically favourable aspects of orthodontic space closure with segmented arch technique and the T-loop type A are clinically reproducible. In our study of eleven patients we found for the isolated canine retraction, as well as for the en masse retraction, controlled types of movement for the active units and maximum anchorage situations for the passive units produced by the torquing force. Because of these good anchorage conditions space closure could be done without headgear. The level of the anchorage segments was negligibly influenced but in the anterior segments a marked tilting was found in several cases. Besides other factors the intrusive force of the T-loops type A must be considered. As a rule the positioning of the T-loop between central and lateral incisor is to be recommended.

Activator Appliances↗
PubMed1991

Identification and determination of the two principal metabolites of minocycline in humans.

A chromatographic method has been developed for the quantification of minocycline in human serum and urine. The chromatographically determined concentration of minocycline correlated well with the microbiologically active concentration in serum. Two metabolites, 9-hydroxyminocycline and N-demethylated minocycline, could be isolated and identified as the principal metabolites of this tetracycline antibiotic. The structure of the 9-hydroxy compound was proved by nuclear magnetic resonance analysis for the first time. About 15% of the drug was actively converted in the body into a substance less microbiologically active than the parent compound and excreted in the urine within 96 h after the application.

Adult↗
PubMed1991

[Tooth germ transplantation or gap closure--a comparative study in the loss of the first molar].

In our study 37 transplanted and 33 mesialized molars by orthodontics were clinically and radiologically compared. The teeth moved by orthodontics showed a better long-term prognosis. As vital teeth with functioning periodontal structures and only slightly shortened roots they were equivalent to healthy teeth. However, the disadvantage of orthodontic space closure is the requirement of a good compliance due to long treatment time. The prognosis of maintaining a transplanted tooth germ is uncertain. One third of the teeth showed an altered periodontium with resorption areas. The danger of a continuing resorption, as well as a late external resorption is still a risk after a long period of time and can eventually lead to tooth loss. As a treatment alternative, germ transplantation may serve as a replacement of a single missing 6-year-molar in adolescence. Orthodontic space closure is indicated at any age with an existing dysgnathia, the loss of several first molars, the loss of space and mesial tipping of the second molars.

Adolescent↗
PubMed1991

Expression of class II molecules on intestinal epithelial cells in humans. Differences between normal and inflammatory bowel disease.

Expression of class II antigens on human intestinal epithelial cells was assessed using a sensitive avidinbiotin-peroxidase technique. HLA-DR was present predominantly in the normal small bowel with diminished but evident expression in the colon. HLA-DP staining was less prominent, and HLA-DQ was absent. In inflammatory bowel disease the expression of both HLA-DR and HLA-DP was increased, but that for HLA-DQ remained absent, suggesting an inherent defect in the ability of intestinal epithelial cells to express HLA-DQ. In related experiments, an interferon gamma-treated malignant epithelial cell line T84 also failed to stain for HLA-DQ and HLA-DP despite the presence of HLA-DR. Isolated RNAs for all three subclasses of HLA-D were detectable by slot-blot analysis, suggesting that the lack of HLA-DQ expression relates to posttranscriptional defects in intestinal epithelium. These and other differences with conventional class II antigen-positive accessory cells (macrophages/B cells) may help to explain the unique properties of intestinal epithelial cells as antigen-presenting cells.

Adenocarcinoma↗
PubMed1991

Effects of endothelin-1 in the isolated heart in ischemia/reperfusion and hypoxia/reoxygenation injury.

The effects of the vasoconstrictor peptide endothelin-1 were examined in the isolated heart during hypoxia, reoxygenation and reperfusion. Isovolumic rat hearts were perfused with Krebs-Henseleit buffer at constant pressure. Cumulative dose-response curves were obtained for endothelin-1 boluses of 0.04 to 400 pmol in five groups of hearts. Coronary flow declined with increasing dosages and was almost abolished at 400 pmol in control hearts. In hearts subjected to mild hypoxia (perfusate PO2 approximately 150 mmHg), the constrictor effect of endothelin-1 was attenuated at moderate dose compared to control hearts (4 vs. 16% flow reduction at 40 pmol; P less than 0.05). The constrictor effect was unaltered in hearts subjected to either 60 min of severe hypoxia (PO2 approximately 35 mmHg) followed by reoxygenation or to 10 min of total ischemia followed by reperfusion (stunning). When hearts were reperfused following 30 min of total ischemia (irreversible injury), the constrictor response to endothelin-1 was potentiated compared to control (e.g. 36 vs. 16% flow reduction at 40 pmol; P less than 0.05). We conclude that endothelin-1 is a potent coronary constrictor in hypoxic, reoxygenated and reperfused heart. The constrictor effect is attenuated during hypoxia, most likely due to the presence of counteracting vasodilator metabolites. During reperfusion, the constrictor effect is unchanged in stunned myocardium, but is augmented in irreversibly injured heart, due to either increased endothelin-1 binding sites or loss of counteracting vasodilator mechanisms such as prostaglandins and/or endothelium-derived relaxing factor.

Animals↗
PubMed1991

[Clinically relevant biomechanics. 3. Critical reflections about the Burstone intrusion mechanics].

A segmented arch for intrusion of front teeth, as described by Burstone, is compared to a coil-and-stylus-model. The mechanics of constructive modifications are analyzed and their consequences for the movements of front teeth are discussed. It is shown, that in some cases extrusive forces occur, while intrusive forces are applied. In these cases it is necessary to reduce intrusive forces below 0.20 Newton per side. In order to avoid extrusive forces, it is recommended to apply intruding forces between the centers of resistance of the central and lateral incisors.

Dental Stress Analysis↗