Direct measurement of the transport properties of a single DNA molecule.
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Biomedical subjects
Publications and source records attributed to D Wirtz.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
INTRODUCTION: The purpose of this experimental study was to determine quantitatively the cement penetration into periprosthetic femoral bone by Icomparing the use of jet-lavage with the conventional syringe irrigation. METHODS: 10 pairs of fresh-frozen human cadaver femora were used for cemented stem implantation, The left femora were irrigated with a syringe device, the right femora with a jet-lavage system. After implantation, all femora were cut into 5-mm slices from proximal to distal with a diamond saw. The scanned slices were analysed using an image processing system which provided a discrimination between implant, cement, and bone as well as an exact determination of the cement area. RESULTS: In all 10 femora, a recognizable improvement of the cement penetration into the periprosthetic bone was demonstrated using the jet-lavage. In the proximal part, the mean cement penetration was 8.6% higher in the jet-lavage group than in the syringe device group. An equivalent tendency towards the jet-lavage pretreated femora was seen in the middle part with 8.7% on average mean and in the distal part with 6.4% on average. Also, when subdividing the periprosthetic area into 4 quadrants, a significant improvement of the cement penetration was found with the exception of the ventro-medial region. CONCLUSION: Cement distribution and penetration is improved using the jet-lavage technique for cleaning the medullary canal of the femur. Therefore, the jet-lavage should be used as a standard procedure in clinical cementing techniques.
PURPOSE: The aim of this long-term study was to evaluate whether the Lance acetabuloplasty for congenital dysplasia of the hip causes a growth disturbance of the acetabular roof during or after puberty. METHOD: 71 hips of 58 patients were followed clinically and radiologically over a maximum time of 16 years after the operative procedure of a Lance acetabuloplasty. The average age of the patients at the time of operation was 2.8 years (1-6 years). In order to assess the growth of the acetabulum in the early and long-term postoperative phase quantitative parameters (acetabular index of Hilgenreiner, CE angle of Wiberg, ACM angle of Idelberger) as well as qualitative parameters (disturbance of the ossification of the acetabulum and the femoral head) were determined in standardized X-rays of the pelvis, done routinely 6 months, 3 years, 5 years, 8 years and at an average of 11 years as the last follow-up examination after the operation. The assessment of these metrical parameters were carried out in accordance to the classification of the study-group "hip dysplasia" of the DGOT (normal--slight pathological--serious pathological) respecting the different age-groups and degrees of dysplasia. RESULTS: Although in the early postoperative phase the acetabular roof showed a positive development (65% of the CE angles could be considered normal 3 years after operation), the further growth of the acetabulum was disturbed in the period of puberty (8 years after operation only 33% of the CE angles could be considered normal, 51% were extremely pathological). And also in the last X-ray control after an average follow-up time of 11 years a significant retardation of the acetabular roof was seen in 51% of all cases. CONCLUSION: The Lance acetabuloplasty seems to damage the Ossa acetabuli, which are as centers of ossification the essential anatomic structures for the growth of the acetabular rim in adolescence. CLINICAL RELEVANCE: Other procedures such as the Salter osteotomy are to be preferred for the therapy of hip dysplasia.
PURPOSE: Is there an absolute operative indication for the abscess-forming spondylodiscitis or is a curing also possible with minimal invasive procedures? METHOD: In a retrospective study over a period from 1986 to 1993, 40 patients with a spondylodiscitis of the thoracic and lumbar spine were treated and then followed up over two years in our Department of Orthopedic Surgery. Using a CT-controlled method of minimal invasive punction and drainage of the abscessed forms of spondylodiscitis, it was to be settled whether these therapeutic procedures result in a normalization of the biochemical inflammatory parameters (CRP) and in a normalization of the CT--as well as MRI-findings. RESULTS: 7 of the 40 patients had a spondylodiscitis with a local abscess, further 7 patients had a gravidation abscess. 92.5% of the cases were treated conservatively and minimal invasively, respectively. In 11 patients the minimal invasive procedure was used in addition to conservative therapy. 3 cases had to be operated on. A recurrence of the spondylodiscitis was seen in 1 patient; complications (n = 2; 1 x pneumonia, 1 x venous thrombosis) occurred in 5% of all patients. CONCLUSION: Minimal invasive therapy with CT-controlled punction or drainage may be a good alternative to the operative intervention in the predominantly old and multimorbid patients with abscessed forms of spondylodiscitis. The risk is minimized, the immobilizing period was 8.7 weeks on average.
Symptomatic hypotension due to ultrafiltration (UF) is one of the most frequent unwanted side effects of dialysis therapy. Using hemoglobinometry for continuous monitoring of blood volume (BV), ultrafiltration rate (UFR) can be adapted to actual changes in BV. A control system is shown in which UFR is set according to a predefined profile of BV. The conditions of control are: relative BV shall decrease steadily; BV shall decrease rapidly during the first 60 min of dialysis, thereafter decrease in BV should be less; UFR shall be as high as possible; and dry weight should be obtained within a given time. Application of this controlled UF method in 10 dialysis patients shows significantly fewer hypotensive periods and muscle cramps compared to conventionally constant UFR. It is concluded that BV controlled UF is an important step toward optimizing dialysis therapy.