| 1. |
- Valentin, Lil, et al.
(author)
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Comparison of 'pattern recognition' and logistic regression models for discrimination between benign and malignant pelvic masses: a prospective cross validation
- 2001
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In: Ultrasound in Obstetrics & Gynecology. - : Wiley. - 1469-0705 .- 0960-7692. ; 18:4, s. 357-365
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Journal article (peer-reviewed)abstract
- OBJECTIVES: To test prospectively the diagnostic performance of two logistic regression models for calculation of individual risk of malignancy in adnexal tumors (the 'Tailor model' and the 'Timmerman model'), and to compare them to that of 'pattern recognition' (subjective evaluation of the gray-scale ultrasound image and color Doppler ultrasound examination). DESIGN: Consecutive women with a pelvic mass judged clinically to be of adnexal origin underwent preoperative ultrasound examination including color and spectral Doppler examination. The same examination techniques and definitions as those used in the studies in which the logistic regression models had been created were used. The Tailor model was tested in 133 women (35 of whom hada malignancy) and the Timmerman model in 82 women (29 of whom had a malignancy). A subset of 79 women (28 of whom had a malignancy) was used to compare the performance of the Tailor model and the Timmerman model by calculating and comparing the areas under the receiver operating characteristics curves of the two models. Sensitivity and specificity with regard to malignancy were calculated for all three methods. RESULTS: Pattern recognition performed better than the two logistic regression models (sensitivity around 85%, specificity around 90%). Using a risk of malignancy of > 50% to indicate malignancy (as suggested in the original publications), the sensitivity of the Tailor model was 69% and the specificity 88% (n = 133). The corresponding values for the Timmerman model were 62% and 79% (n = 82). The receiver operating characteristics curves showed the two logistic regression models to have similar diagnostic properties (area under the curve, 0.87 vs. 0.84; P = 0.25; n = 79). The diagnostic performance of the mathematical models was much poorer in this study than in those in which the models had been created. CONCLUSION: The poor diagnostic performance of the mathematical models can probably be explained by subtle differences in definitions and examination technique and by differences between the original tumor populations and the study population. For mathematical models to be generally useful, they probably need to be created on the basis of a very large number of tumors, and the variables in the model must be unequivocally defined and the examination technique meticulously standardized.
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| 2. |
- Briel, J W, et al.
(author)
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Prevalence and risk factors for ischemia, leak, and stricture of esophageal anastomosis: Gastric pull-up versus colon interposition
- 2004
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In: Journal of the American College of Surgeons. - : Ovid Technologies (Wolters Kluwer Health). - 1879-1190 .- 1072-7515. ; 198:4, s. 536-541
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Journal article (peer-reviewed)abstract
- BACKGROUND: Reports of esophageal anastomotic complications often involve more gastric than colonic reconstructions and are incomplete because of fragmented followup by physicians unfamiliar with the surgical procedure. STUDY DESIGN: Three hundred ninety-three consecutive esophagectomy patients had prevalence and risk factors determined for graft ischemia and anastomotic leak; 363 of these patients followed for more than I month (median 15 months) had prevalence and risk factors determined for anastomotic stricture. RESULTS: Conduit ischemia occurred in 36 (9.2%) and anastomotic leak in 43 patients (10.9%). Risk factor for ischemia was comorbid conditions requiring therapy (Odds ratio [OR]: 2.2 [95% CI 1.1-4.3]), and for leak were ischemia (OR: 5.5 [95% CI 2.5-12. 1]), neoadjuvant therapy (OR: 2.2 [95% CI 1.1-4-5]), and comorbid conditions (OR: 2.1 [95% Cl 1.1-3.9]). A stricture developed in 80 patients (22.0%). Risk factors were ischemia (OR: 4.4 [95% Cl 2.0-9.6]), anastomotic leak (OR: 3.8 [95% C11.9-7.6]), and increasing preoperative weight (p = 0.022). The prevalence of ischemia was similar after gastric (10.4%) versus colonic (7.4%) reconstruction; leak and stricture were more common (14.3% versus 6.1%, p = 0.013, 31.3% versus 8.7%, p < 0.000 1, respectively) and strictures were more severe (11.2% versus 2%, p = 0.00 1) after gastric pull-up. Patients free of ischemia and leak who developed stricture were more likely to have had a gastric pull-up (25% versus 7%, p < 0. 000 1). Dilatation was effective treatment in 93% of patients. CONCLUSIONS: After esophagectomy 10% of patients will develop conduit ischemia or an anastomotic leak and 22% will develop anastornotic stricture. Anastomotic leak and strictures are more common and the strictures are more severe after gastric pull-up compared with colon interposition. Dilatation is a safe and effective treatment.
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| 3. |
- Hagen-Thorn, Anna, et al.
(author)
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Macronutrients in tree stems and foliage: a comparative study of six temperate forest species planted at the same sites
- 2004
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In: Annals of Forest Science. - : EDP Sciences. - 1286-4560 .- 1297-966X. ; 61:6, s. 489-498
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Journal article (peer-reviewed)abstract
- Common European tree species ( oak, ash, beech, birch, lime and spruce) planted in adjacent stands on six sites were compared in terms of macronutrient concentrations in foliar and stem wood ( including bark) biomass. The nutrient concentrations in both biomass compartments were much more dependent on species than on site although soil conditions differed between the sites. Differences between species regarding stem wood nutrient concentrations only partly corresponded to the differences in species foliage. The concentrations in spruce were considerably lower than in deciduous species, except P in foliage, and Ca in both stem wood and foliar biomass. Differences were also observed between the deciduous species both regarding foliar and stem wood nutrient concentrations. The differences should be considered when modelling nutrient circulation in forest stands and when evaluating the long-term sustainability of forest management.
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| 5. |
- Kläger, S L, et al.
(author)
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Humoral immune response of Simulium damnosum s.l. following filarial and bacterial infections.
- 2002
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In: Parasitology. - 0031-1820. ; 125:Pt 4, s. 359-66
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Journal article (peer-reviewed)abstract
- The time-course of the humoral immune response of female blackflies after a challenge with bacteria, different Onchocerca microfilariae species, bacterial endotoxin and microfilarial extract was investigated. Strong bacteriolytic and growth inhibition activities against the Gram-positive bacterium Micrococcus luteus were induced by all agents. Specific differences were found in activity levels and time-course. Notably the endotoxin lipopolysaccharide (LPS) induced a very early, profound bacteriolytic and antibacterial response, which declined within a day after injection. In contrast, the bacteriolytic activities after Escherichia coli D31 and Onchocerca microfilariae infections were lower, but remained elevated over the observation period of 4 days. The bacteriolytic activity was correlated to a haemolymph protein with a molecular weight of around 14 kDa. Anti-Gram-positive activity in the E. coli infected group appeared within the first 6 h. However, it took 4 days in the microfilarial infected blackflies to reach significant levels. The active agent was identified to be a peptide with a molecular weight of around 4-4.5 kDa. Activity against the Gram-negative bacteria E. coli was detected in blackflies injected with E. coli D31, O. dukei microfilariae and microfilarial extract on days 1 and 4 after injection. The immune response in S. damnosum s.l. naturally infected via a bloodmeal on cattle supported the findings of the experimental infections. Similarities of the immune response kinetics between bacterial and filarial infections suggested that intracellular Wolbachia bacteria, released from microfilariae, could be responsible for the antibacterial response. This is supported by the observation that the induction of an immune response in the Drosophila melanogaster mbn-2 cell line by the filarial extract is blocked by polymyxin B, which forms inactive complexes with bacterial LPS.
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| 6. |
- Spies, Hagen, et al.
(author)
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Local Models for Dynamic Processes in Image Sequences
- 2002
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In: Workshop Dynamic Perception. - Bochum. ; , s. 59-64
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Conference paper (other academic/artistic)abstract
- We present a computational framework that extends classical image velocity estimation to include more general parameters of dynamic brightness changes. The introduced method allows for an extraction of these parameters, ranging from models of linear illumination changes over diffusion and decay constants to expansion rates. We illustrate the benefit of such an extension on a real image sequence with illumination changes. We also introduce a new depth estimation technique termed depth from diffusion and apply it to some real examples.
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