| 1. |
- Cullberg, Marie, 1958-
(författare)
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Direct Thrombin Inhibitors in Treatment and Prevention of Venous Thromboembolism: Dose – Concentration – Response Relationships
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For prevention and treatment of thrombotic diseases with an anticoagulant drug it is important that an adequate dose is given to avoid occurrence or recurrence of thrombosis, without increasing the risk of bleeding and other adverse events to unacceptable levels. The aim of this thesis was to develop mathematical models that describe the dose-concentration (pharmacokinetic) and concentration-response (pharmacodynamic) relationships of direct thrombin inhibitors, in order to estimate optimal dosages for treatment and long-term secondary prevention of venous thromboembolism (VTE).Population pharmacokinetic-pharmacodynamic models were developed, based on data from clinical investigations in healthy volunteers and patients receiving intravenous inogatran, subcutaneous melagatran and/or its oral prodrug ximelagatran. The benefit-risk profiles of different ximelagatran dosages were estimated using clinical utility functions. These functions were based on the probabilities and fatal consequences of thrombosis, bleeding and elevation of the hepatic enzyme alanine aminotransferase (ALAT).The studies demonstrate that the pharmacokinetics of melagatran and ximelagatran were predictable and well correlated to renal function. The coagulation marker, activated partial thromboplastin time (APTT), increased non-linearly with increasing thrombin inhibitor plasma concentration. Overall, the systemic melagatran exposure (AUC) and APTT were similarly predictive of thrombosis and bleedings. The identified relationship between the risk of ALAT-elevation and melagatran AUC suggests that the incidence approaches a maximum at high exposures. The estimated clinical utility was favourable compared to placebo in the overall study population and in special subgroups of patients following fixed dosing of ximelagatran for long-term secondary prevention of VTE. Individualized dosing was predicted to add limited clinical benefit in this indication.The models developed can be used to support the studied dosage and for selection of alternative dosing strategies that may improve the clinical outcome of ximelagatran treatment. In addition, the models may be extrapolated to aid the dose selection in clinical trials with other direct thrombin inhibitors.
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| 2. |
- Karlsson, Christina, et al.
(författare)
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Tissue microarray validation : a methodologic study with special reference to lung cancer
- 2009
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - : American Association for Cancer Research. - 1055-9965 .- 1538-7755. ; 18:7, s. 2014-2021
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although tissue microarray (TMA) studies of histopathologic material have been frequently reported in studies of malignant diseases, the question of sample size (i.e., the diameter and the number of tissue cylinders investigated) has been rarely discussed. This study addresses the methodologic question of sample size in a variety of tumor types.MATERIAL AND METHODS: Material from 29 cases of lung carcinoma (small cell, squamous cell, and adenocarcinomas) was examined immunohistochemically for Ki-67 and p53 expression in virtually constructed cylinders of different diameters. The influence of tissue sample size (i.e., different numbers of virtual cylinders) was also investigated. Results from Ki-67 evaluation were analyzed as a continuous variable, whereas p53 expression was scored. p53 evaluations based on scoring in cylinders versus scoring of whole sections were also compared. Furthermore, 10 cases of endometrial and breast carcinomas were evaluated for estrogen receptor, Ki-67, and HER2 by scoring up to five cylinders.RESULTS AND CONCLUSIONS: Tissue cylinders of 0.6 and 1.0 mm diameters were compared and found equally informative about Ki-67 expression (intraclass correlation, 0.96). A statistical approach considering intraindividual and interindividual variation data is presented, indicating that in this specific setting three cylinders per case is an adequate sample size for TMA studies. Further sampling yields only a small gain in accuracy as determined by Ki-67 quantification and p53 scoring (kappa-coefficient, 0.9). For endometrial and breast tissues, TMA scoring of three cylinders yielded excellent agreement (kappa, >0.75) compared with whole-section scoring.
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| 3. |
- Andersson, Patiyan, 1978-, et al.
(författare)
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PIK3CA, HRAS and KRAS gene mutations in human penile cancer
- 2008
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Ingår i: Journal of Urology. - New York, USA : Ovid Technologies (Wolters Kluwer Health). - 0022-5347 .- 1527-3792. ; 179:5, s. 2030-2034
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The knowledge of somatic mutations that arise in penile cancer is limited. We examined the dysregulation of components in the phosphatidylinositol 3-kinase and Ras pathways. Materials and Methods: Using single stranded conformational analysis and direct sequencing we performed mutational analysis of the PIK3CA, PTEN, HRAS, KRAS, NRAS and BRAF genes in 28 penile tumors. Results: We identified somatic missense mutations in 11 of the 28 penile cancer samples (39%). In the PIK3CA gene 8 mutations (29%) were identified that were E542K or E545K. In the HRAS gene a G12S and a Q61L mutation were found (7%). The KRAS gene contained 1 mutation (3%), that is a G12S change. PIK3CA mutations were found in all grades and stages, whereas HRAS and KRAS mutations were found in larger and more advanced tumors. The mutations were mutually exclusive, suggesting that dysregulation of either pathway is sufficient for the development and progression of penile carcinoma. Conclusions: The high frequency of mutations in the PIK3CA, HRAS and KRAS genes leads us to believe that dysregulation of the phosphatidylinositol 3-kinase or Ras pathway is significant for the development and progression of penile carcinoma.
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| 4. |
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| 5. |
- Bååthe, Sofie, et al.
(författare)
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Population pharmacokinetics of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, in atrial fibrillation patients receiving long-term anticoagulation therapy
- 2006
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Ingår i: Clinical Pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 45:8, s. 803-819
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ximelagatran is an oral direct thrombin inhibitor for the prevention of thromboembolic disease. After oral administration, ximelagatran is rapidly absorbed and bioconverted to its active form, melagatran. Objective: To characterise the pharmacokinetics of melagatran in patients with nonvalvular atrial fibrillation (NVAF) receiving long-term treatment for prevention of stroke and systemic embolic events. Methods: A population pharmacokinetic model was developed based on data from three phase 11 studies (1177 plasma concentration observations in 167 patients, treated for up to 18 months) and confirmed by including data from two phase III studies (8702 plasma concentration observations in 3188 patients, treated for up to 24 months). The impact of individualised dosing on pharmacokinetic variability was evaluated by simulations of melagatran concentrations based on the pharmacokinetic model. Results: Melagatran pharmacokinetics were consistent across the studied doses and duration of treatment, and were described by a one-compartment model with first-order absorption and elimination. Clearance of melagatran was correlated to creatinine clearance, which was the most important predictor of melagatran exposure (explained 54% of interpatient variance in clearance). Total variability (coefficient of variation) in exposure was 45%; intraindividual variability in exposure was 23%. Concomitant medication with the most common long-term used drugs in the study population had no relevant influence on melagatran pharmacokinetics. Simulations suggested that dose adjustment based on renal function or trough plasma concentration had a minor effect on overall pharmacokinetic variability and the number of patients with high melagatran exposure. Conclusion: The pharmacokinetics of melagatran in NVAF patients were predictable, and consistent with results from previously studied patient populations. Dose individualisation was predicted to have a low impact on pharmacokinetic variability, supporting the use of a fixed-dose regimen of ximelagatran for long-term anticoagulant therapy in the majority of NVAF patients.
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| 6. |
- Cullberg, M., et al.
(författare)
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Pharmacokinetics of ximelagatran and relationship to clinical response in acute deep vein thrombosis
- 2005
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Ingår i: Clin Pharmacol Ther. - : Springer Science and Business Media LLC. - 0009-9236 .- 1532-6535. ; 77:4, s. 279-90
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Our objective was to characterize the pharmacokinetics of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, and the relationship between melagatran exposure and clinical outcome in patients with acute deep vein thrombosis. METHODS: A population pharmacokinetic analysis was performed on samples from patients with deep vein thrombosis participating in a randomized dose-finding study (THRombin Inhibitor in Venous thrombo-Embolism [THRIVE I]). Patients received fixed doses of oral ximelagatran (24, 36, 48, or 60 mg twice daily) for 12 to 16 days. Thrombus size was evaluated by venography before and after treatment. Exposure-response curves were characterized for the probability of regression, no change, and progression of the thrombus extension and of having a bleeding-related event, by use of logistic regression models. RESULTS: The pharmacokinetics of melagatran (1836 samples in 264 patients) was predictable, without significant time or dose dependencies. Clearance after oral administration (population mean, 27.3 L/h) was correlated with creatinine clearance (P < 10(-6)), and volume of distribution (population mean, 176 L) was correlated with body weight (P = 2 x 10(-5)). Gender, age, or smoking did not significantly influence melagatran pharmacokinetics after the influence of renal function and body weight was accounted for. Unexplained interpatient variability values in total plasma clearance and bioavailability were 19% and 21%, respectively. The median area under the plasma melagatran concentration versus time curve across all patients and dose levels was 3.22 h x micromol/L (5th-95th percentiles, 1.35-7.69). There was no significant relationship between area under the plasma concentration versus time curve and change in thrombus extension (P = .59) or bleeding-related events (P = .77), and the estimated exposure-response curves were relatively flat. CONCLUSIONS: The pharmacokinetics of melagatran in patients with acute deep vein thrombosis was predictable after oral ximelagatran administration. Shallow exposure-response curves for efficacy and bleeding indicate that there is no need for individualized dosing or therapeutic drug monitoring in the patient population studied.
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| 7. |
- Joerger, Markus, et al.
(författare)
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Population pharmacokinetics and pharmacodynamics of doxorubicin and cyclophosphamide in breast cancer patients : a study by the EORTC-PAMM-NDDG
- 2007
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Ingår i: Clinical Pharmacokinetics. - 0312-5963 .- 1179-1926. ; 46:12, s. 1051-1068
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To investigate the population pharmacokinetics and pharmacodynamics of doxorubicin and cyclophosphamide in breast cancer patients. Patients and methods: Sixty-five female patients with early or advanced breast cancer received doxorubicin 60 mg/m(2) over 15 minutes followed by cyclophosphamide 600 mg/m(2) over 15 minutes. The plasma concentration-time data of both drugs were measured, and the relationship between drug pharmacokinetics and neutrophil counts was evaluated using nonlinear mixed-effect modelling. Relationships were explored between drug exposure (the area under the plasma concentration-time curve [AUC]), toxicity and tumour response. Results: Fifty-nine patients had complete pharmacokinetic and toxicity data. In 50 patients with measurable disease, the objective response rate was 60%, with complete responses in 6% of patients. Both doxorubicin and cyclophosphamide pharmacokinetics were associated with neutrophil toxicity. Cyclophosphamide exposure (the AUC) was significantly higher in patients with at least stable disease (n = 44) than in patients with progressive disease (n = 6; 945 mu mol . h/L [95% CI 889, 1001] vs 602 mu mol . h/L [95% CI 379, 825], p = 0.0002). No such correlation was found for doxorubicin. Body surface area was positively correlated with doxorubicin clearance; AST and patient age were negatively correlated with doxorubicin clearance; creatinine clearance was positively correlated with doxorubicinol clearance; and occasional concurrent use of carbamazepine was positively correlated with cyclophosphamide clearance. Conclusions: The proposed inhibitory population pharmacokinetic-pharmacodynamic model adequately described individual neutrophil counts after administration of doxorubicin and cyclophosphamide. In this patient population, exposure to cyclophosphamide, as assessed by the AUC, might have been a predictor of the treatment response, whereas exposure to doxorubicin was not. A prospective study should validate cyclophosphamide exposure as a predictive marker for the treatment response and clinical outcome in this patient group
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| 8. |
- Joerger, Markus, et al.
(författare)
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Population pharmacokinetics and pharmacodynamics of paclitaxel and carboplatin in ovarian cancer patients : a study by the European organization for research and treatment of cancer-pharmacology and molecular mechanisms group and new drug development group.
- 2007
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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 13:21, s. 6410-6418
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Paclitaxel and carboplatin are frequently used in advanced ovarian cancer following cytoreductive surgery. Threshold models have been used to predict paclitaxel pharmacokinetic-pharmacodynamics, whereas the time above paclitaxel plasma concentration of 0.05 to 0.2 μmol/L (tC > 0.05−0.2) predicts neutropenia. The objective of this study was to build a population pharmacokinetic-pharmacodynamic model of paclitaxel/carboplatin in ovarian cancer patients. Experimental Design: One hundred thirty-nine ovarian cancer patients received paclitaxel (175 mg/m2) over 3 h followed by carboplatin area under the concentration-time curve 5 mg/mL*min over 30 min. Plasma concentration-time data were measured, and data were processed using nonlinear mixed-effect modeling. Semiphysiologic models with linear or sigmoidal maximum response and threshold models were adapted to the data. Results: One hundred five patients had complete pharmacokinetic and toxicity data. In 34 patients with measurable disease, objective response rate was 76%. Neutrophil and thrombocyte counts were adequately described by an inhibitory linear response model. Paclitaxel tC > 0.05 was significantly higher in patients with a complete (91.8 h) or partial (76.3 h) response compared with patients with progressive disease (31.5 h; P = 0.02 and 0.05, respectively). Patients with paclitaxel tC > 0.05 > 61.4 h (mean value) had a longer time to disease progression compared with patients with paclitaxel tC > 0.05 < 61.4 h (89.0 versus 61.9 weeks; P = 0.05). Paclitaxel tC > 0.05 was a good predictor for severe neutropenia (P = 0.01), whereas carboplatin exposure (Cmax and area under the concentration-time curve) was the best predictor for thrombocytopenia (P < 10−4). Conclusions: In this group of patients, paclitaxel tC > 0.05 is a good predictive marker for severe neutropenia and clinical outcome, whereas carboplatin exposure is a good predictive marker for thrombocytopenia.
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| 9. |
- Karlsson, Mikael, et al.
(författare)
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Experimental determination of the aero-acoustic properties of an in-duct flexible plate
- 2008
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Ingår i: 14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference). - Reston, Virigina : American Institute of Aeronautics and Astronautics (AIAA).
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Konferensbidrag (refereegranskat)abstract
- The potential reduction of the aeroacoustic noise generated by an in duct plate, byallowing it to be flexible, is studied experimentally. The test object is a triangular plateinserted at an angle in a circular flow duct. Results are given for the active and passiveacoustic properties. In addition the flow field and the vibrations of the plate arecharacterized. It is found that an appropriately yielding plate reduces the flow generatednoise while keeping the mean flow field unaffected.
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| 10. |
- Klingberg, Jenny, 1978, et al.
(författare)
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Observations of Ground-level Ozone and NO2 in Northernmost Sweden, Including the Scandian Mountain Range
- 2009
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Ingår i: Ambio. ; 38:8, s. 448-451
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Tidskriftsartikel (refereegranskat)abstract
- Ozone was measured using passive diffusion samplers at alpine Latnjajaure (980 m above sea level [asl]) in the northern Scandian Mountain Range during spring and summer 2006–2008, and year-round at three further sites in northernmost Sweden 2004–2008. These observations were compared with ozone concentrations from three permanent monitoring stations using ultraviolet absorption instruments. Ozone concentrations at Latnjajaure were higher than at the closest monitoring site, illustrating the importance of high elevation for ozone. At the northern sites the ozone spring peak was more pronounced, higher, and earlier (April maximum) compared to a site in south Sweden (May maximum). During summer, ozone concentrations were higher in south Sweden. Presently, the growing season largely starts after the ozone spring peak in north Sweden but is likely to start earlier in the future climate. This could lead to an increased risk for ozone effects on vegetation if the current yearly ozone cycle persists.
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