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Biomedical subjects

U Stratmann

Publications and source records attributed to U Stratmann.

46 records · Page 3Linked to original sources
PubMed1992

[Elemental analytical and quantitative morphometric determination of the synthetic resin residues and enamel avulsion after the removal of metal brackets].

A number of clinical and experimental studies were performed to assess the quality of the enamel-adhesive-bracket bond. The aim was to present a combined method that enables the investigator both to examine the surface of metal brackets quantitative-morphometrically and to detect the presence of enamel particles. To this end, 38 metal brackets were examined in the scanning electron microscope. An EDAX-detecting unit was used to analyze morphologically conspicuous structures and identified them as enamel particles. The extent of adhesive remnants and enamel particles was quantified using the image analysis system IBAS. In 24 brackets (53%) bonding adhesive residue was found on the bracket base. In 18 brackets (47%) enamel particles were identified on the adhesive-bearing brackets. This method is easier to carry out and enables a more accurate quantification of enamel particles than the Adhesive Remnant Index. Since it can be applied universally to examine recommended improvements to adhesive technique, it facilitates their assessment.

Composite Resins↗
PubMed1992

The rat esophagus: ultrastructure and radiological aspects of tissue response after 1320 nm Nd:YAG laser irradiation.

Morphological tissue response towards laser treatment was investigated in the esophagi of adult Wistar rats by light- and transmission electron microscopy. The specimens were fixed by perfusion immediately, 2 days and 14 days after laser treatment in order to assess different stages of the healing process. The epithelium of the lasercentre was completely destroyed in the immediate group. The connective tissue showed damaged cells, fused collagenous fibres and occluded blood vessels. Smooth muscle cells presented a vacuolated sarcoplasm and pycnotic nuclei. The cross striation of skeletal muscle cells had disappeared and their nuclei were karyolytic. In a distance of 4 mm from the lasercentre all wall tissues had an almost normal appearance. After 2 days the morphological feature of the lasercentre was the same as in the immediate group. In a distance of 2 mm some layers of flat and intact epithelial cells were observed below the necrotic epithelium. The adjacent connective tissue was infiltrated by inflammatory cells. After 14 days the formation of granulation tissue had caused an occlusion of the lumen in the lasercentre. In a distance of 2 mm the lumen was patent and the wall tissues had been partly restored. As the rat esophagus serves as a model for esophagotracheal fistulae in newborn children we assume the 1320 nm Nd:YAG laser to be a possible application in occlusion of these fistulae.

Animals↗
PubMed1992

A new device for long-term continuous enteral nutrition of rats by elementary diet via gastrostomy, following extensive oesophageal or lower gastrointestinal surgery.

A device for intragastric nutrition of unsedated and minimally restrained rats under complete alimentary abstinence has been developed. The cannulation system consists of an infusion pump, modified glass syringe as flow swivel, rat-harness and a silicone-tube-gastrostomy. The animals were kept in special cages and coprophagy was prevented by an own model of faecal collection cup. Methionine and Ca-glycerophosphate had to be added to a commercial elementary diet. The rats were allowed to move freely during intragastric infusion, which was applied for 14 to 28 days in 118 Wistar-rats (350-400 g). They maintained weight on an energy supply of 86.4 kcal/day.

Animals↗
PubMed1991

[The morphological results of the use of a pulsed krypton fluoride excimer laser for enamel conditioning].

Although there have been many advances in the field of acid etching, major problems still present. For the most part, these are the unpredictability of the effects of etching, the lack of control of the depth of etching over the long term, and the development of enamel fractures occurring on debonding. The aim of this study was to investigate the morphological effects of enamel conditioning using a pulsed krypton fluoride excimer laser (wavelength 248 nm). Scanning electron microscopic examination revealed a surface similar to that produced by peripheral etching; no signs of thermal damage were to be seen. The requirements that have to be met by a modern laser considered as a possible alternative to conventional acid etching, are discussed.

Acid Etching, Dental↗
PubMed1991

Electron probe X-ray microanalysis of calcium and phosphorus distribution in developing hamster tooth germs in vitro and in vivo.

The aim of the present study was to investigate the spatial distribution of Ca and P in dentin and enamel of developing first (M1) and second (M2) maxillary hamster molars (age: 3-5 days) in comparison with cultured molars. For culturing the germs were dissected from 3-day-old hamsters and incubated for 1 and 2 days, respectively, in a modified BGJb medium. Electron probe X-ray measurements were carried out on 3 regions extending in a vertical axis from cusp tip over cusp middle to cusp base next to the cervical loop region. Neither the in vivo nor the in vitro group was statistically different in the Ca and P concentration in the regions of dentin. In both groups the measurements in enamel showed a gradient with an increase in Ca and P from enamel surface towards dentin-enamel junction and a gradient with an increase from cusp base towards cusp tip. Direct comparison of the in vivo group with the in vitro group did not demonstrate a statistical difference between the mineral content of the 4-day-old germs and the 1-day culture germs, respectively the 5-day-old germs and the 2-day culture germs. The results indicate a high correspondence between the mineralization process of in vitro and in vivo tooth germ development.

Aging↗
PubMed1991

Light- and electron-microscopic study of the rat esophagus following intraluminal argon laser irradiation.

36 rat esophagi were irradiated by argon laser via an applicator with circumferential light distribution. They were perfused with glutaraldehyde and studied by light and transmission electron microscopy immediately, 2 days and 14 days after irradiation. Immediately after irradiation the laser center showed destruction of the keratinized stratified squamous epithelium. The collagenous fibers of the connective tissue were altered; fibrocytes and fibroblasts were severely damaged, and the microvascular lumina were occluded. The smooth muscle tissue and skeletal muscle tissue showed myofilament defects and initial karyonecrosis. There was decreasing damage of both fiber types up to 4 mm from the laser center. After 2 days the morphology of the laser center was not different from that seen immediately after irradiation. At a distance of 2 mm a partly differentiated new epithelium emerged below the necrotic epithelium. An inflammatory reaction was found in the connective tissue. After 14 days the esophageal wall was replaced and the lumen was occluded by young granulation tissue in the former laser center. Peripherally the esophageal wall appeared almost normal. As the rat esophagus serves as a model for esophagotracheal fistulae in newborn children, our findings indicate that the argon laser should be capable of occluding these fistulae likewise.

Animals↗
PubMed1991

Effect of sulfur dioxide inhalation on the respiratory tract of the rat.

In order to study the initial effect of SO2 exposure by electron microscopy, Wistar rats were subjected to the gas for 8 hours at a concentration of 800 ppm. A gradient of decreasing damage was observed in the tracheobronchial tree in peripheral direction. The trachea epithelium showed the most severe lesions represented by groups of detached cells, necrotic cells and disappearance of cilia and goblet cells. The entire apical surface was composed of short protrusions. A complementary ultracytochemical chromatin labelling method could demonstrate a gradient with a decreasing labelling rate of epithelial cells towards the peripheral airways. The cytochemical findings may indicate an increased mitotic and metabolic activity of epithelial cells surviving in a region of marked morphological damage as a response to high SO2 concentration. This nuclear activity seems to decrease in peripheral parts of the respiratory tract along the gradient of decreasing morphological damage.

Animals↗
PubMed1991

[Improved model of a fecal collection device for the prevention of coprophagia in the rat].

Previous fecal collection cups with tape fixation frequently led to serious necroses of the rat tail due to strangulations, and did not allow for growth of the tail. A recently developed new model gives space for rapidly growing tails and is securely fixed by a cannula perforating both fecal collection cup and tail. It is transparent, cheap to be made, and easy to empty and was tested in 118 animals for two and four weeks. In no case the cup did loosen or had to be removed due to infections, strangulations or any local problems.

Animals↗
PubMed1989

[Macro-anatomical studies on the palpability of the lateral inferior pterygoid muscle].

In order to diagnose muscular dysfunction associated with the lower pterygoid muscle common intraoral palpation techniques require this muscle to be touched with the fingertip or a probing instrument. A macro-anatomical study using heads of humans has been done to demonstrate morphometrically the origin of the M. pterygoideus lateralis inferior in relation to neighbouring structures. In a majority of cases intraoral palpation of the lower pterygoid muscle is probably impossible.

Humans↗