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| 2. |
- Björk, Thomas, et al.
(författare)
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Comparison of analysis of the different prostate-specific antigen forms in serum for detection of clinically localized prostate cancer
- 1996
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Ingår i: Urology. - 1527-9995. ; 48:6, s. 882-888
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare different forms and ratios of serum prostate-specific antigen (PSA) to determine which form or ratio provides optimal diagnostic specificity and sensitivity in distinguishing between benign prostatic hyperplasia (BPH) and clinically localized prostate cancer. METHODS: Serum samples were obtained from 47 patients with BPH and 39 with clinically localized prostate cancer. Patients with BPH underwent either transurethral resection of the prostate or transurethral microwave thermotherapy. Patients with prostate cancer, all of whom had no metastases on radionucleotide bone scans and no pelvic lymph node involvement, underwent either radical external beam radiation therapy or radical retropubic prostatectomy. All patients had pretreatment serum PSA levels between 1 and 20 ng/mL. The different forms of serum PSA (free PSA [PSA-F], PSA complexed to alpha 1-antichymotrypsin [PSA-ACT], and total PSA [PSA-T]) were measured using different monoclonal antibodies against PSA and ACT and immunofluorometric assay techniques. Furthermore, three ratios (PSA-F/PSA-T, PSA-ACT/PSA-T, and PSA-F/PSA-ACT) were calculated. RESULTS: By receiver operating characteristic curve analysis, the performance of the different forms and ratios were compared. The PSA-F/PSA-T ratio had the greatest area under the curve (AUC, 0.776), significantly larger than that for PSA-T (0.612; P = 0.024). For PSA-ACT/PSA-T, the AUC was 0.695 (P = 0.283 versus PSA-T) and 0.773 for PSA-F/PSA-ACT (P = 0.051 versus PSA-T). At a cutoff level < 0.17, PSA-F/PSA-T had a sensitivity of 79%, a specificity of 66%, and a positive predictive value of 66% compared with 74%, 38%, and 50%, respectively, for PSA-T at a cutoff level > 4.0 ng/mL. CONCLUSIONS: The PSA-F/PSA-T ratio gives the best diagnostic performance compared with that for other forms and ratios of PSA and will reduce the number of prostatic biopsies in patients with BPH.
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| 3. |
- Braun, M.W., et al.
(författare)
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Multi-Level Pseudo-Random Signal Design and 'Model-on-Demand' Estimation Applied to Nonlinear Identification of a RTP Wafer Reactor
- 1999
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Ingår i: Preceedings of the 1999 American Control Conference. - Linköping : Linköping University Electronic Press. - 0780349903 ; , s. 1573-1579 vol.3
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Guidelines are presented for specifying the design parameters of multi-level pseudo-random sequences in a manner useful for “plant-friendly” nonlinear system identification. These multi-level signals are introduced into a rapid thermal processing wafer reactor simulation and compared against a well-designed pseudo-random binary sequence (PRBS). The resulting data serves as a database for a “model on demand” (MoD) predictor. MoD estimation is attractive because it requires less engineering effort to model a nonlinear plant, compared to global nonlinear models such as neural networks. The improved fit of multi-level signals over the PRBS signal, as well as the usefulness of the MoD estimator, is demonstrated on validation data.
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| 6. |
- Oesterling, Joseph E., et al.
(författare)
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Free, Complexed and Total Serum Prostate Specific Antigen : The Establishment of Appropriate Reference Ranges for their Concentrations and Ratios
- 1995
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Ingår i: The Journal of urology. - 0022-5347. ; 154:3, s. 1090-1095
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Prostate specific antigen (PSA) exists in the serum in several molecular forms that can be measured by immunodetectable assays: free PSA, PSA complexed to alpha 1-antichymotrypsin (complexed PSA) and total PSA, which represents the sum of the free and complexed forms. We determined the normal distribution of values and established the appropriate reference ranges for these 3 molecular forms of PSA and their ratios (free-to-total, complexed-to-total and free-to-complexed PSA). Knowing the amount and ratio of these molecular forms appears to be useful in enhancing the ability of PSA to distinguish potentially curable prostate cancer from benign prostatic hyperplasia and in decreasing the number of unnecessary prostate biopsies. Materials and Methods: A total of 422 healthy men 40 to 79 years old was randomly chosen from the male population of Olmsted County Minnesota and underwent a detailed clinical examination that included digital rectal examination, serum PSA determination and transrectal ultrasound to exclude the presence of prostate cancer. Using newly developed, monoclonal-monoclonal immunofluorometric assays for each molecular form, the free, complexed and total PSA, and the ratios of these 3 forms were determined for each study participant. Results: All 3 molecular forms correlated directly with patient age (r = 0.45, r = 0.43 and r = 0.45, respectively). Using the 95th percentile, the recommended age-specific reference ranges for the free, complexed and total PSA forms, respectively, are 0.5, 1.0 and 2.0 ng./ml. for men 40 to 49 years old; 0.7, 1.5 and 3.0 ng./ml. for men 50 to 59 years old; 1.0, 2.0 and 4.0 ng./ml. for men 60 to 69 years old, and 1.2, 3.0 and 5.5 ng./ml. for men 70 to 79 years old. With regard to each of the ratios (free-to-total, complexed-to-total and free-to-complexed PSA) none correlated with patient age. As a result, the appropriate upper limit of normal (95th percentile) for all 3 ratios is constant for men of all ages. These reference ranges are greater than 0.15 for free-to-total PSA ratio, less than 0.70 for complexed-to-total PSA ratio and greater than 0.25 for free-to-complexed PSA ratio. The free-to-total PSA ratio will have its greatest value for men with a serum PSA value between 2 and 10 ng./ml. Conclusions: The establishment of appropriate reference ranges for free, complexed and total PSA as well as the ratios will allow the practicing urologist to incorporate these new parameters into the diagnostic evaluation of men at risk for early, potentially curable prostate cancer.
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| 7. |
- Piironen, Timo, et al.
(författare)
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In vitro stability of free prostate-specific antigen (PSA) and prostate- specific antigen (PSA) complexed to α1-antichymotrypsin in blood samples
- 1996
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Ingår i: Urology. - 0090-4295. ; 48:6 SUPPL., s. 81-87
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. To study the in vitro stability of free and complexed forms of prostate specific antigen (PSA) in blood samples in order to establish guidelines for specimen handling, in particular for the clinical utility of the analysis of percentage free PSA. Methods. Blood samples were collected and processed to generate serum, heparin plasma, and EDTA plasma. Three different two-site immunoassays were used to measure the concentrations of total PSA (PSA-T), free form of PSA (PSA-F), and PSA-α1-antichymotrypsin complex (PSA-ACT) in order to determine the effect of repeated freezing and thawing, delayed separation of serum from blood cells, and stability during storage at 4°C and 30°C. Results. Five cycles of freezing and thawing introduced no statistically significant changes in the measured concentrations of PSA-T, PSA-F, or PSA-ACT. The effect of storing blood samples at room temperature for 1-6 h before separation of serum revealed a statistically significant decrease only for PSA-F after 5.5 h of storage (mean decrease 3.5%). PSA-T and PSA-ACT showed good stability in both serum and plasma samples, whereas PSA-F, after 1 week of storage at 4°C, decreased on average by 28.8%, 7.8%, and 5.6%, respectively, in serum, heparin plasma, and EDTA plasma. The decreases of PSA-F at 4°C were statistically significant (P < 0.05) relative to the controls (samples stored at -20°C) after storage for 23 h in serum, 86 h in heparin plasma, and 71 h in EDTA plasma. When the same samples were stored at 30°C for 24 h, only the mean decrease of PSA-F (4.8%) in serum was statistically significant. Conclusions. PSA-F in blood samples is less stable than PSA-ACT. It is not advisable to store samples on the clot, especially if time and temperature cannot be controlled. Serum samples should be stored frozen if not analyzed during the same day. After thawing, samples can be stored up to 23 h at 4°C prior to analysis. The use of plasma samples improves the stability of free PSA.
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| 9. |
- Stenman, Anders, et al.
(författare)
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Comparison of Global Nonlinear Models and "Model-on-Demand" Estimation Applied to Identification of a RTP Wafer Reactor
- 1999
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Ingår i: Preceedings of the 38th IEEE Conference on Decision and Control. - Linköping : Linköping University Electronic Press. - 0780352505 ; , s. 3950-3955 vol.4
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Konferensbidrag (refereegranskat)abstract
- "Model on Demand" (MoD) simulation of the temperature dynamics in a simulated Rapid Thermal Process-ing (RTP) reactor is compared against various types of global models (ARX, semiphysical, combined semiphysical with neural net). The identication data is generated from a m-level pseudo-random sequence input whose parameters are specied systematically using a priori information readily available to the engineer. The MoD estimator outperforms the ARX model and two semi-physical models, while matching the performance of a combined semi-physical with neural net model. This makes MoD estimation an appealing alternative to global methods because of its reduced engineering eort and simplified a priori knowledge regarding model structure.
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| 10. |
- Stenman, Anders, et al.
(författare)
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On Adaptive Smoothing of Empirical Transfer Function Estimates
- 1999
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Ingår i: Proceedings of the 14th IFAC World Congress. - Linköping : Linköping University Electronic Press. ; , s. 415-420
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The determination of the right resolution parameter when estimating frequency functions for linear systems is a trade-off between bias and variance. Traditional approaches, like 'window-closing' employ a global resolution parameter - the window width - that is tuned by ad hoc methods, usually visual inspection of the results. Here we suggest an adaptive method that tunes such parameters by an automatic procedure. A further benefit is that the tuning can be done locally, i.e., different resolutions can be used in different frequency bands. The ideas are based on local polynomial regression and the 'just-in-time'-model concept. The advantages of the method are illustrated in numerical examples.
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