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- Fritzson, Peter, et al.
(författare)
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Biochemical Mathematical Modeling with Modelica and the BioChem Library
- 2007
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Konferensbidrag (refereegranskat)abstract
- Considering the large amounts of data that is nowadays produced in the biochemistry (functional genomics) it is difficult to extract the information from the measurements. There is currently also a great interest in the development of novel analytical technologies for rapid screening of disease symptoms in pharmaceutical and clinical ap-plications. Modeling and simulation can provide a useful help in understanding the rela-tions of the measured substances and to minimize the need for measurements. The Bio-Chem library presented here is the first free Modelica library available for mathematical modeling of biochemical processes. Three examples are shown to illustrate the library. First, a simple insulin model is presented. Then a simplified model of cholesterol to-gether with simulations are shown. Next, a simple drug model together with parameter estimation in NONMEN are presented. The BioChem library allows for fast and end-user friendly modeling of biomedical systems. The graphical user interface provides graphics similar to that used in the description of metabolic pathways in biochemistry.
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- Green, Henrik, 1975-
(författare)
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Pharmacogenetic Studies of Paclitaxel in Ovarian Cancer : focus on interindividual differences in pharmacodynamics and pharmacokinetics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ovarian cancer is one of the most common female cancer diseases in the world today and in Sweden more than 800 new cases are diagnosed every year. The standard treatment consists of chemotherapy with paclitaxel in combination with carboplatin after initial cytoreductive surgery. The response to treatment and the severity of adverse drug reactions after chemotherapy varies greatly among individuals, and one of the most important factors responsible for these differences is now recognized to be the genetic variability. One of the major obstacles to successful treatment is drug resistance. Several potential mechanisms have been suggested for the resistance to paclitaxel, such as mutations in the target protein β-tubulin, single nucleotide polymorphisms (SNPs) in the gene ABCB1, which encodes the transport protein P-glycoprotein. P-glycoprotein can mediate efflux of various drugs from cancer cells as well as from the circulation into the intestinal lumen, and overexpression and/or high activity leads to drug resistance and/or increased elimination. Another reason might be the high interindividual variability of paclitaxel plasma concentrations, which has been suggested to be influenced by variability in metabolic enzymes, such as CYP2C8 and CYP3A4, and transport proteins e.g. P-glycoprotein.In the studies constituting this thesis we have investigated the possibilities of predicting the pharmacokinetics of paclitaxel as well as the tumor response and adverse drug reactions after chemotherapy in the preparation of personalized chemotherapy. We studied the correlation between the response and the presence of mutations in the dominant β-tubulin gene and SNPs in ABCB1. DNA from 40 ovarian tumors was screened for sequence variations in the β-tubulin gene without finding any, showing that β-tubulin mutations are rare and unlikely to be a clinically relevant resistance mechanism for paclitaxel. The SNPs G2677T/A and C3435T in the ABCB1 gene were determined in 53 ovarian cancer tumors from patients with poor (progressive disease or relapse within one year) or good (disease-free survival of more than one year) response to paclitaxel-carboplatin chemotherapy. Patients homozygously mutated for G2677T/A had a higher probability of responding to chemotherapy. There was also a dose-dependent influence of the number of mutated alleles on the response to paclitaxel treatment. No correlation was found for the C3435T variant.By using a newly developed quantitative LC/MS method for the simultaneous determination of paclitaxel and its hydroxymetabolites in human plasma we assessed the individual elimination of paclitaxel in 33 ovarian cancer patients. The patients were genotyped for SNPs in the ABCB1, CYP2C8 and CYP3A4 genes and their in vivo CYP3A4 enzyme activity, tumor response and toxicity, especially the neurotoxicity, were determined. Patients heterozygous for G/A in position 2677 in ABCB1 had a significantly higher clearance of paclitaxel than patients with the wild type or homozygously mutated, but not compared to patients carrying the G/T alleles. A lower clearance of paclitaxel was also found for patients heterozygous for CYP2C8*3 when stratified according to the ABCB1 G2677T/A genotype. The CYP3A4 enzyme activity in vivo affected the relative influence of CYP2C8 and CYP3A4 on the metabolism, but not the total clearance of paclitaxel. The exposure to paclitaxel was correlated to the neurotoxicity, but not to the treatment response. In conclusion, our findings suggest that the SNP G2677T/A in the ABCB1 gene, but not β-tubulin mutations, might be a predictor for paclitaxel response and that the interindividual variability in paclitaxel pharmacokinetics might be predicted by ABCB1 and CYP2C8 genotypes and provide useful information for individualized chemotherapy.
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- Green, Henrik, 1975-
(författare)
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Pharmacogenomics of importance for paclitaxel chemotherapy
- 2008
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Ingår i: Pharmacogenomics (London). - : Future Medicine Ltd. - 1462-2416 .- 1744-8042. ; 9:6, s. 671-674
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Tidskriftsartikel (refereegranskat)abstract
- Paclitaxel (Taxol®) has a broad activity spectrum and is clinically used, often in combination with carboplatin, to treat breast, ovarian and lung cancer. The response to treatment and the severity of adverse drug reactions after chemotherapy varies greatly among individuals, and one of the most important factors responsible for these differences is now recognized to be the genetic variability. However, so far only genetic variants of ABCB1 have been indicated to be associated with response and pharmacokinetics of paclitaxel. Commercially, the patent on paclitaxel has expired: however, from a healthcare perspective, it would be beneficial to identify patients with risk of poor response or high risk of toxicity to reduce hospitalization costs. This artiicle focuses on the pharmacogenomic background for paclitaxel response and interindividual variability.
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