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Biomedical subjects

J Overbeck

Publications and source records attributed to J Overbeck.

14 recordsLinked to original sources
PubMed2000

Bactericidal effect of extracorporeal shock waves on Staphylococcus aureus.

Despite considerable knowledge about the effects of shock waves on eukaryotic soft tissues, no data are available concerning their effect on prokaryotic micro-organisms. In vitro studies on the bactericidal effect of extracorporeal shock waves on staphylococci were performed with energy levels that are standard for the disintegration of calculi. Suspensions containing 10(4)-10(5) cfu of Staphylococcus aureus/ml were sealed in plastic tubes and exposed to shock waves, resulting in a mean decrease of 3.1 log(10). Whereas impulse rates of > or =350 resulted in a decrease of cfu/ml equalling the detection limit, lower numbers of impulses did not result in an appreciable bactericidal effect. The bactericidal effect of extracorporeal shock waves might provide the basis for the development of novel therapeutic strategies for bacterial infections.

Lithotripsy↗
PubMed1996

Clinical and biomechanical aspects of external fixation of the pelvis.

OBJECTIVE: The aim was to evaluate the mechanical stability of several traditional and modern external fixators in unstable pelvic ring disruption. DESIGN: In a laboratory study external and internal fixation techniques were tested in seven fresh and five embalmed human pelves with a disruption of the pubic symphysis and one sacroiliac joint (type C1.2 injury according to the Tile-AO classification). BACKGROUND: Stability provided by external fixation depends upon many factors, with the residual pelvic stability being the most important. METHODS: Simulating a single-leg stance, the load was applied quasi-statically to the acetabulum of the unstable hemipelvis. Device failure was defined as displacement >10 mm either at the symphysis pubis or the sacroiliac joint. RESULTS: The frame with the highest failure load (fresh versus embalmed specimens) was the Egbers configuration with the AO fixator (analysis of variance; P < 0.05). Failure was noted at 114.9 N versus 129.5 N. Augmentation of the Mono-Tube by additional internal posterior osteosynthesis gave the following results: sacral bars 325.4 N versus 217.8 N, plate fixation 294.3 N versus 215.8 N, lag screws 338.4 N versus 215.8 N. Failure loads of hybrid fixation of the Orthofix were as follows: sacral bars 257.9 N versus 213.9 N, plate fixation 333.5 N versus 245.3 N, lag screws 397.3 N versus 280.6 N. The differences between the two fixators were not statistically significant. CONCLUSIONS: No single external frame provided sufficient stability. The addition of a posterior internal fixation significantly increased failure loads and controlled the weight-bearing pelvic elements.

Journal Article↗
PubMed1994

[Follow-up of fracture healing--indications and clinical relevance of direct radiographic magnification in comparison with conventional roentgen imaging].

Comparison of 83 magnification radiographs with corresponding conventional X-rays showed that direct radiographic magnification (DIMA) yielded additional information in 39 cases (47%), which had implications for the treatment in 19 cases (22.9%). In 11 cases callus was first visualized in magnification radiography; the earliest evidence of callus was found 14 days after surgery. Since magnification radiography means the region that can be examined is smaller, conventional radiographs were necessary in 32.5% of cases to find the position of the fracture in long bones. For statistical evaluation interobserver analysis was performed, anatomical and pathological structures being graded according to four levels. Magnification radiography proved superior in all structures examined. Magnification radiography can be recommended as an additional method to monitor fracture healing. Computed radiography was used together with magnification radiography to reduce the radiation dose and to perform image processing including simulation of conventional technique and edge enhancement. DIMA is a valuable tool in the evaluation of fracture stability and in the adjustment of distraction rates in limb-lengthening procedures.

Adult↗
PubMed1991

[Therapy of a malignant sympathetic paraganglioma of the organ of Zuckerkandl--a case report].

We present a case report on a 35-year-old patient in whom a malignant sympathetic paraganglioma of the organ of Zuckerkandl was the cause of severe hypertension with excessive perspiration at night. Since curative surgery was not possible medical treatment was initiated. Interferon alfa 2b (Intron A, Essex Pharma) and the somatostatin-analogue SMS 201-995 (Sandostatin, Sandoz) had no effect on catecholamine production and progression of the tumor. Treatment with alpha-methyl-para-tyrosin (MPT, [Metyrosin], Demser, MSD) turned out to be an effective and well tolerable therapy in this patient with peritoneal carcinosis. Clinical and hormonal progression of the paraganglioma resumed only after two years of therapy, which constitutes the longest documented period of time of successful MPT treatment. The superior efficacy of MPT in our patient should encourage postoperative medical treatment with MPT in malignant pheochromocytoma or malignant paraganglioma, particularly when the tumor turns out to be resistent to alpha blocking drugs.

Adult↗
PubMed1981

Microcomputer-assisted biomass determination of plankton bacteria on scanning electron micrographs.

Although biovolume is a better measure of biomass than is cell number, biovolumes have rarely been measured because their evaluation is extremely time-consuming. We developed a microcomputer system that assists cell size measurements on images of filtered plankton: scanning electron micrograph negatives were projected on a digitizer field, bacterial length and width were marked by a cursor, and coordinates were directly transferred to an MOS 6502 microcomputer (KIM 1). The dialogue program BABI organized and controlled the digitizer measurements in cooperation with the user, enabled corrections, and printed out results with 95% confidence limits and sample description. The time for scanning electron micrograph preparation was reduced to 15 min (quick transfer to Freon 113 during filtration and air drying). Altogether, this biovolume determination took about 2.5 h for confidence limits of +/-15%. Examples are given for applications of the method: (i) comparison of 10 lakes (with specific activities for glucose uptake and for heterotrophic CO(2) fixation); (ii) ranges of biomass parameters in one lake; (iii) diurnal cycles (with synchronizing effects, uptake of algal exudates, and calculation of daily growth). This method is discussed in relation to other biomass methods (epifluorescent microscopy, lipopolysaccharide technique, frequency of dividing cells) and the problem of biovolume-to-carbon conversions.

Journal Article↗
PubMed1977

Autonomous growth fluctuations of the methane oxidizing bacterial strain M 102 in batch and continuous culture.

The growth rates of the methane oxidizing strain M 102 were unstable. In unlimited batch cultures they ranged from 0 to 1.4 d-1 with most frequent values around 0.25 d-1. The yield coefficients were between 0.1 and 1.6 mg dry weight per mg methane and varied from 1.1 to 0.4 even in a continuous culture with the limiting substrate in the gas phase. It was possible to prove intermittent release and uptake of organic compounds by the definition of a "net" yield coefficient and its theoretical boundaries. The response of the fluctuations to varying dilution frequencies and culture volumes showed analogies to controlled systems. The simultaneous variations in the age distribution and in the excretion pattern revealed the dependence of the dividing stages on a product of the young cells. The mathematical description of the findings suggests that the young cells favor division at their own disadvantage. The consequent autonomous synchronisations are the reason for the unstable growth rates of strain M 102.

Bacteria↗
PubMed1976

[The use of an enzyme-kinetic-method for bacteriological examinations of heavy polluted surface waters (author's transl)].

The greatest fraction of nutrients dissolved in water are organic substances which are decomposed, transformed and mineralized by heterotrophic microorganisms. For this reason, investigations concerning energy transfer in an aquatic ecosystem, or practical examinations of the pollution load of surface waters, cannot be set up when based exclusively on more or less good counts of microorganisms of the production or destruction group. Above all, it is important for heterotrophic bacteria that productivity parameters for these numerical estimations are also provided. PARSON and STRICKLAND were successful in measuring the uptake of organic material in waters with uptake-kinetic methods; HOBBIE and WRIGHT developed a method for measuring the uptake of marked test-substrates in certain concentration ranges. As a result, for these substrates it was possible to measure the turnover in natural populations. Consequently, after frequent improvement of the technique in determining the decomposition rates of individual organic substrates, a way was found not only to determine static descriptions of an aquatic biotope, but also to make possible a dynamic description of nutrient transfers. The kinetic parameters computed from these measurements are: the maximum uptake velocity (Vmax), the turnover velocity (Tt) and the transport constant (Kt) (Michaelis Constant). The maximum uptake velocity of a substrate can be regarded as the "heterotrophic capacity" of the biotope for this substrate. One restriction is, however, that only quickly assimilatable substrates can be used, as for example hexoses, organic acids, amino acids, etc. Since this technique was tested practically only in oligotrophic waters, this study undertakes to investigate its applicability in polluted biotopes and to answer the question whether a decomposition gradient is reflected in the kinetic data. A small eutrophic lake in the eastern section of the Holstein Lake District (350 ha, 9.5 m mean water depth) was chosen as the test biotope. Emptying into the lake was the runoff of a biological water treatment plant with 12,000 population equivalents and without notable business and industry. In a rectangular investigation area at first with 30 sampling stations positioned close to the outlet of the water treatment plant into the lake, kinetic tests were carried out in 48 hour intervals and then compared with bacteriological, chemical and meteorological sample results taken at the same time. Two typical result-blocks are illustrated (Fig. 1-4, 5-8). The first shows four successive test days with periodically strong wind and light to fairly strong but short periods of precipitation. The second block illustrates conditions during a following period of fair weather with only very light wind intensities. The corresponding conditions of the stratification of the drainage water in the investigation area are illustrated by the distribution of coliform organisms. In two other tables the kinetic parameters and individual, dominant data are contrasted numerically...

Bacteria↗