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Lindbom L, Pihlgren P, Jonsson EN, Jonsson N. PsN-Toolkit--a collection of computer intensive statistical methods for non-linear mixed effect modeling using NONMEM. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2005; 79:241-57. [PMID: 16023764 DOI: 10.1016/j.cmpb.2005.04.005] [Citation(s) in RCA: 955] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Revised: 03/16/2005] [Accepted: 04/02/2005] [Indexed: 05/03/2023]
Abstract
PsN-Toolkit is a collection of statistical tools for pharmacometric data analysis using the non-linear mixed effect modeling software NONMEM. The toolkit is object oriented and written in the programming language Perl using the programming library Perl-speaks-NONMEM (PsN). Five methods: the Bootstrap, the Jackknife, Log-likelihood Profiling, Case-deletion Diagnostics and Stepwise Covariate Model building are included as separate classes and may be used in user-written Perl scripts or through stand-alone command line applications. The tools are designed with the ability to cooperate and with an emphasis on common structures for workflow and result handling. Parallel execution of independent tool sections is supported on shared memory multiprocessor (SMP) computers, Mosix/openMosix clusters and distributed computing environments following the NorduGrid standard. In conclusion, PsN-Toolkit makes it easier to use the Bootstrap, the Jackknife, Log-likelihood Profiling, Case-deletion Diagnostics and Stepwise Covariate Model building in pharmacometric data analysis.
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Jonsson EN, Karlsson MO. Xpose--an S-PLUS based population pharmacokinetic/pharmacodynamic model building aid for NONMEM. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 1999; 58:51-64. [PMID: 10195646 DOI: 10.1016/s0169-2607(98)00067-4] [Citation(s) in RCA: 821] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The building of population pharmacokinetic/pharmacodynamic (PK/PD) models is a time consuming and complicated task. This is partly due the lack of specialized tools for the visualization and exploration requirements of this type of analysis. In this paper we present Xpose, a model building aid for population PK/PD analysis using NONMEM, which simplifies the task of producing documentation, data set checkout plots, goodness of fit plots and graphical model comparison. It also facilitates covariate model building by the use of stepwise generalized additive modeling (GAM), bootstrap of the GAM analyses and tree based modeling. The plots and analyses are presented in the form of a text based menu system and the only thing the user has to do is to make NONMEM produce one or more table files named in a specific way.
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Lindbom L, Ribbing J, Jonsson EN. Perl-speaks-NONMEM (PsN)--a Perl module for NONMEM related programming. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2004; 75:85-94. [PMID: 15212851 DOI: 10.1016/j.cmpb.2003.11.003] [Citation(s) in RCA: 630] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Revised: 11/25/2003] [Accepted: 11/27/2003] [Indexed: 05/24/2023]
Abstract
The NONMEM program is the most widely used nonlinear regression software in population pharmacokinetic/pharmacodynamic (PK/PD) analyses. In this article we describe a programming library, Perl-speaks-NONMEM (PsN), intended for programmers that aim at using the computational capability of NONMEM in external applications. The library is object oriented and written in the programming language Perl. The classes of the library are built around NONMEM's data, model and output files. The specification of the NONMEM model is easily set or changed through the model and data file classes while the output from a model fit is accessed through the output file class. The classes have methods that help the programmer perform common repetitive tasks, e.g. summarising the output from a NONMEM run, setting the initial estimates of a model based on a previous run or truncating values over a certain threshold in the data file. PsN creates a basis for the development of high-level software using NONMEM as the regression tool.
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Abstract
PURPOSE One important task in population pharmacokinetic/pharmacodynamic model building is to identify the relationships between the parameters and demographic factors (covariates). The purpose of this study is to present an automated procedure that accomplishes this. The benefits of the proposed procedure over other commonly used methods are (i) the covariate model is built for all parameters simultaneously, (ii) the covariate model is built within the population modeling program (NONMEM) giving familiar meaning to the significance levels used, (iii) it can appropriately handle covariates that varies over time and (iv) it is not dependent on the quality of the posterior Bayes estimates of the individual parameter values. For situations in which the computer run-times are a limiting factor, a linearization of the non-linear mixed effects model is proposed and evaluated. METHODS The covariate model is built in a stepwise fashion in which both linear and non-linear relationships between the parameters and covariates are considered. The linearization is basically a linear mixed effects model in which the population predictions and their derivatives with respect to the parameters are fixed from a model without covariates. The stepwise procedure as well as the linearization was evaluated using simulations in which the covariates were taken from a real data set. RESULTS The covariate models identified agreed well with what could be expected based on the covariates that were actually supported in each of the simulated data sets. The predictive performance of the linearized model was close to that of the non-linearized model. CONCLUSIONS The proposed procedure identifies covariate models that are close to the model supported by the data set as well as being useful in the prediction of new data. The linearized model performs nearly as well as the non-linearized model.
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Wählby U, Jonsson EN, Karlsson MO. Assessment of actual significance levels for covariate effects in NONMEM. J Pharmacokinet Pharmacodyn 2001; 28:231-52. [PMID: 11468939 DOI: 10.1023/a:1011527125570] [Citation(s) in RCA: 237] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The objectives of this study were to assess the difference between actual and nominal significance levels, as judged by the likelihood ratio test, for hypothesis tests regarding covariate effects using NONMEM, and to study what factors influence these levels. Also, a strategy for obtaining closer agreement between nominal and actual significance levels was investigated. Pharmacokinetic (PK) data without covariate relationships were simulated from a one compartment i.v. bolus model for 50 individuals. Models with and without covariate relationships were then fitted to the data, and differences in the objective function values were calculated. Alterations were made to the simulation settings; the structural and error models, the number of individuals, the number of samples per individual and the covariate distribution. Different estimation methods in NONMEM were also tried. In addition, a strategy for estimating the actual significance levels for a specific data set, model and parameter was investigated using covariate randomization and a real data set. Under most conditions when the first-order (FO) method was used, the actual significance level for including a covariate relationship in a model was higher than the nominal significance level. Among factors with high impact were frequency of sampling and residual error magnitude. The use of the first-order conditional estimation method with interaction (FOCE-INTER) resulted in close agreement between actual and nominal significance levels. The results from the covariate randomization procedure of the real data set were in agreement with the results from the simulation study. With the FO method the actual significance levels were higher than the nominal, independent of the covariate type, but depending on the parameter influenced. When using FOCE-INTER the actual and nominal levels were similar. The most important factors influencing the actual significance levels for the FO method are the approximation of the influence of the random effects in a nonlinear model, a heteroscedastic error structure in which an existing interaction between interindividual and residual variability is not accounted for in the model, and a lognormal distribution of the residual error which is approximated by a symmetric distribution. Estimation with FOCE-INTER and the covariate randomization procedure provide means to achieve agreement between nominal and actual significance levels.
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Gardulf A, Andersen V, Björkander J, Ericson D, Frøland SS, Gustafson R, Hammarström L, Jacobsen MB, Jonsson E, Möller G. Subcutaneous immunoglobulin replacement in patients with primary antibody deficiencies: safety and costs. Lancet 1995; 345:365-9. [PMID: 7845120 DOI: 10.1016/s0140-6736(95)90346-1] [Citation(s) in RCA: 220] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Immunoglobulins (IgG) as replacement therapy in primary antibody deficiencies can be given as intramuscular injections, or as intravenous or subcutaneous infusions. Our aims were to obtain information on the frequency of adverse systemic reactions during subcutaneous therapy, the occurrence and intensity of tissue reactions at the infusion sites, and serum IgG changes. Furthermore, we compared costs between the different replacement regimes. Our study included 165 patients (69 women, 96 men, aged 13-76 years) with primary hypogammaglobulinaemia or IgG-subclass deficiencies. Data were compiled from questionnaires filled in by the patients and from their medical records. 33,168 subcutaneous infusions (27,030 in home therapy) had been given. 106 (of which 16 were at home) adverse systemic reactions (100 mild, 6 moderate) were recorded in 28 patients (17%). No severe or anaphylactoid reactions occurred. Despite large immunoglobulin volumes given during 434 patient years (28,480 infusions), no signs have been found that indicate the transmission of hepatitis virus. Transient tissue reactions occurred at the infusion sites but were not troublesome to most patients and we found significant increases in mean serum IgG. The use of subcutaneous instead of intravenous infusions at home would reduce the yearly cost per patient for the health-care sector by US $10,100 in Sweden alone. We conclude that subcutaneous administration of IgG is a safe and convenient method of providing immunoglobulins. We were able to reach serum IgG concentrations similar to those by the intravenous therapy and we found that the method could also be used successfully in patients with previous severe or anaphylactoid reactions to intramuscular injections.
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Wählby U, Jonsson EN, Karlsson MO. Comparison of stepwise covariate model building strategies in population pharmacokinetic-pharmacodynamic analysis. AAPS PHARMSCI 2002; 4:E27. [PMID: 12645999 PMCID: PMC2751316 DOI: 10.1208/ps040427] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The aim of this study was to compare 2 stepwise covariate model-building strategies, frequently used in the analysis of pharmacokinetic-pharmacodynamic (PK-PD) data using nonlinear mixed-effects models, with respect to included covariates and predictive performance. In addition, the effects of stepwise regression on the estimated covariate coefficients were assessed. Using simulated and real PK data, covariate models were built applying (1) stepwise generalized additive models (GAM) for identifying potential covariates, followed by backward elimination in the computer program NONMEM, and (2) stepwise forward inclusion and backward elimination in NONMEM. Different versions of these procedures were tried (eg, treating different study occasions as separate individuals in the GAM, or fixing a part of the parameters when the NONMEM procedure was used). The final covariate models were compared, including their ability to predict a separate data set or their performance in cross-validation. The bias in the estimated coefficients (selection bias) was assessed. The model-building procedures performed similarly in the data sets explored. No major differences in the resulting covariate models were seen, and the predictive performances overlapped. Therefore, the choice of model-building procedure in these examples could be based on other aspects such as analyst- and computer-time efficiency. There was a tendency to selection bias in the estimates, although this was small relative to the overall variability in the estimates. The predictive performances of the stepwise models were also reasonably good. Thus, selection bias seems to be a minor problem in this typical PK covariate analysis.
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Ribbing J, Jonsson EN. Power, Selection Bias and Predictive Performance of the Population Pharmacokinetic Covariate Model. J Pharmacokinet Pharmacodyn 2004; 31:109-34. [PMID: 15379381 DOI: 10.1023/b:jopa.0000034404.86036.72] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Identification and quantification of covariate relations is often an important part of population pharmacokinetic/pharmacodynamic (PK/PD) modelling. The covariate model is regularly built in a stepwise manner. With such methods, selection bias may be a problem if only statistically significant covariates are accepted into the model. Competition between multiple covariates may further increase selection bias, especially when there is a moderate to high correlation between the covariates. This can also result in a loss of power to find the true covariates. The aim of this simulation study was to investigate the effect on power, selection bias and predictive performance of the covariate model, when altering study design and system-related quantities. Data sets with 20-1000 subjects were investigated. Five covariates were created by sampling from a multivariate standard normal distribution. The true covariate was set up to have no, low, moderate and high correlation to the other four covariates, respectively. Data sets, in which each individual had two or three PK observations, were simulated using a one-compartment i.v. bolus model. The true covariate influenced clearance according to one of several magnitudes. Different magnitudes of residual error and inter-individual variability in the structural model parameters were also introduced to the simulation model. A total of 7400 replicate data sets were simulated independently for each combination of the above conditions. Models with one of the five simulated covariates influencing clearance and the model without any covariate were fitted to the data. The probability of selecting (according to a pre-specified P-value) the different covariates, along with the estimated covariate coefficient, was recorded. The results show that selection bias is very high for small data sets (< or = 50 subjects) simulated with a weak covariate effect. If selected under these circumstances, the covariate coefficient is on average estimated to be more than twice its true value, making the covariate model useless for predictive purposes. Surprisingly, even though competition from false covariates caused substantial loss in the power of selecting the true covariate, the already high selection bias increased only marginally. This means that the bias due to competition is negligible if statistical significance is also required for covariate selection. Bias and predictive performance are direct functions of power, only indirectly affected by study design and system-related quantities. Mainly because of selection bias, low-powered covariates can be expected to harm the predictive performance when selected. For the same reason these low-powered covariates may falsely appear to be clinically relevant when selected. If the aim of an analysis is predictive modelling, we do not recommend stepwise selection or significance testing of covariates to be performed on small or moderately sized data sets (<50-100 subjects).
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Karlsson MO, Jonsson EN, Wiltse CG, Wade JR. Assumption testing in population pharmacokinetic models: illustrated with an analysis of moxonidine data from congestive heart failure patients. JOURNAL OF PHARMACOKINETICS AND BIOPHARMACEUTICS 1998; 26:207-46. [PMID: 9795882 DOI: 10.1023/a:1020561807903] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Deriving a population pharmacokinetic model from real data is always associated with numerous assumptions. Violations of these assumptions, especially if undetected, may lead to inappropriate conclusions being made from the analysis. Routinely, only a few of the assumptions are explicitly stated and justified in the reporting of a population model. Here, we attempt to be exhaustive in the presentation of the assumptions made in the course of an analysis of moxonidine pharmacokinetics. The different ways that assumptions were justified, through experience, graphical examination, or additional modeling, are outlined. Models for relaxing assumptions regarding the covariate and statistical submodels, not previously reported in the area of population pharmacokinetic modeling, are also described.
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Abrahmsén L, Dohlsten M, Segrén S, Björk P, Jonsson E, Kalland T. Characterization of two distinct MHC class II binding sites in the superantigen staphylococcal enterotoxin A. EMBO J 1995; 14:2978-86. [PMID: 7542584 PMCID: PMC394357 DOI: 10.1002/j.1460-2075.1995.tb07300.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Bacterial superantigens (SAgs) are potent activators of T lymphocytes and play a pathophysiological role in Gram-positive septic shock and food poisoning. To characterize potential MHC class II binding sites of the bacterial SAg staphylococcal enterotoxin (SE) A, we performed alanine substitution mutagenesis throughout the C-terminus and at selected sites in the N-terminal domain. Four amino acids in the C-terminus were shown to be involved in MHC class II binding. Three of these amino acids, H225, D227 and H187, had a major influence on MHC class II binding and appeared to be involved in coordination of a Zn2+ ion. Alanine substitution of H225 and D227 resulted in a 1000-fold reduction in MHC class II affinity. Mutation at F47, which is equivalent to the F44 previously shown to be central in the MHC class II binding site of the SAg, SEB, resulted in a 10-fold reduction in MHC class II affinity. The combination of these mutations in the N- and C-terminal sites resulted in a profound loss of activity. The perturbation of MHC class II binding in the various mutants was accompanied by a corresponding loss of ability to induce MHC class II-dependent T cell proliferation and cytotoxicity. All of the SEA mutants were expressed as Fab-SEA fusion proteins and found to retain an intact T cell receptor (TCR) epitope, as determined in a mAb targeted MHC class II-independent T cell cytotoxicity assay.(ABSTRACT TRUNCATED AT 250 WORDS)
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Bardhan KD, Bianchi Porro G, Bose K, Daly M, Hinchliffe RF, Jonsson E, Lazzaroni M, Naesdal J, Rikner L, Walan A. A comparison of two different doses of omeprazole versus ranitidine in treatment of duodenal ulcers. J Clin Gastroenterol 1986; 8:408-13. [PMID: 3531313 DOI: 10.1097/00004836-198608000-00005] [Citation(s) in RCA: 113] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In a study involving three centers, 105 patients with duodenal ulcer proven by endoscopy were randomly assigned to treatment with either the H+, K+, ATPase inhibitor omeprazole (20 mg or 40 mg taken as a single morning dose), or ranitidine (150 mg morning and night). It was a double-blind study using a double-dummy technique. Clinical assessment and laboratory investigations were carried out at 2, 4, and 8 weeks; endoscopy was done at 2 weeks, and if not healed, at 4 and 8 weeks. The patients in the three treatment groups were well matched. Significantly more patients treated with omeprazole healed compared with ranitidine at 2 weeks (p = 0.007) and at 4 weeks (p = 0.007), but there was no statistically significant difference between the two omeprazole groups. Pain was of similar severity at the start in all groups, but patients treated with omeprazole had fewer days with pain (median values being omeprazole 20 mg: 2 days; omeprazole 40 mg: 1 day; ranitidine: 7 days). The difference between the combined omeprazole groups and ranitidine was significant (p less than 0.02). There was also a tendency towards less severe daytime pain on omeprazole during the first week. The difference was statistically significant between omeprazole (40 mg) and ranitidine for days 2-7 (p less than 0.01). No change in laboratory screen attributable to drug treatment occurred. After healing, 79 patients entered a 6-month follow-up study with endoscopy at 3 and 6 months or whenever symptoms occurred. After 6 months relapses occurred in 14/24, 19/23, and 15/25 after 20 mg omeprazole, 40 mg omeprazole, and ranitidine, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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Hamberg AK, Dahl ML, Barban M, Scordo MG, Wadelius M, Pengo V, Padrini R, Jonsson EN. A PK-PD model for predicting the impact of age, CYP2C9, and VKORC1 genotype on individualization of warfarin therapy. Clin Pharmacol Ther 2007; 81:529-38. [PMID: 17301738 DOI: 10.1038/sj.clpt.6100084] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study was to characterize the relationship between warfarin concentrations and international normalized ratio (INR) response and to identify predictors important for dose individualization. S- and R-warfarin concentrations, INR, and CYP2C9 and VKORC1 genotypes from 150 patients were used to develop a population pharmacokinetic/pharmacodynamic model in NONMEM. The anticoagulant response was best described by an inhibitory E(MAX) model, with S-warfarin concentration as the only exposure predictor for response. Delay between exposure and response was accounted for by a transit compartment model with two parallel transit compartment chains. CYP2C9 genotype and age were identified as predictors for S-warfarin clearance, and VKORC1 genotype as a predictor for warfarin sensitivity. Predicted INR curves indicate important steady-state differences between patients with different sets of covariates; differences that cannot be foreseen from early INR assessments alone. It is important to account for CYP2C9 and VKORC1 genotypes and age to improve a priori and a posteriori individualization of warfarin therapy.
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Research Support, Non-U.S. Gov't |
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Svensson BG, Nilsson A, Jonsson E, Schütz A, Akesson B, Hagmar L. Fish consumption and exposure to persistent organochlorine compounds, mercury, selenium and methylamines among Swedish fishermen. Scand J Work Environ Health 1995; 21:96-105. [PMID: 7618064 DOI: 10.5271/sjweh.16] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVES This study assessed dietary habits and exposure to selenium, persistent organochlorine compounds, methylmercury, and methylamines among Swedish fishermen. METHODS Two hundred and fifty randomly selected subjects from a cohort of 2896 fishermen from the Swedish east coast (Baltic Sea) and 8477 fishermen from the west coast (Skagerrak and Kattegatt) were interviewed along with 250 referents. Subgroups of fishermen and referents from different coastal areas were also selected for blood and urine sampling. RESULTS The interview data showed that fishermen ate almost twice as much fish as the 250 referents from the general population. The blood levels of mercury were twice as high, and the plasma selenium levels were 10-15% higher in the fishermen than in the referents. There was, however, no difference between the fishermen's cohorts with respect to these variables. Fishermen from the east coast ate more fatty fish than fishermen from the west coast, and they also had higher blood levels of persistent organochlorine compounds such as polychlorinated biphenyls and polychlorinated dibenzo p-dioxins and furans (present in fatty fish species in the Baltic Sea) than both the westcoast fishermen and the referents. CONCLUSIONS A cohort of Swedish eastcoast fishermen might be a suitable study base for epidemiologic studies on the mortality and cancer morbidity associated with dietary exposure to persistent organochlorine compounds.
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Clinical Trial |
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Sigurdsson S, Thorlacius S, Tomasson J, Tryggvadottir L, Benediktsdottir K, Eyfjörd JE, Jonsson E. BRCA2 mutation in Icelandic prostate cancer patients. J Mol Med (Berl) 1997; 75:758-61. [PMID: 9383000 DOI: 10.1007/s001090050162] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Molecular genetic analysis of prostate cancer has gained considerable attention in recent years. The hope is to find genetic markers that can help to determine which patients are likely to develop a progressive or lethal disease and would therefore benefit from early treatment. The BRCA2 gene on chromosome 13 has been associated with familial male and female breast cancer. A founder mutation in this gene has been detected in the Icelandic population. This is a 5-bp deletion that leads to an early termination and truncated protein. Clustering of prostate cancers in some of the Icelandic BRCA2 families implies that mutation carriers are at increased risk of developing cancer of the prostate. The aim of the study was to investigate this mutation in Icelandic prostate cancer patients related to BRCA2 positive breast cancer probands and to estimate the prevalence of this mutation in unselected prostate cancer patients. To examine the potential role of this mutation in prostate cancer we analyzed prostate cancer cases from 16 BRCA2 families and all available samples from individuals diagnosed with prostate cancer in Iceland over a period of 1 year. The risk ratio of prostate cancer was 4.6 (1.9-8.8) in first-degree relatives and 2.5 (1.2-4.6) in second-degree relatives of the 16 BRCA2 positive breast cancer probands. Of 26 prostate cancer cases found in these families 12 were analyzed, and 8 of these (66.7%) had the BRCA2 mutation. All of these patients developed an advanced disease, and all have died of prostate cancer (median survival 22.5 months). Among unselected cases 3.1% (2/65) had the mutation and developed an advanced disease as well. This specific mutation in the BRCA2 gene is found in a subset of Icelandic prostate cancer cases and appears to be a marker for poor prognosis.
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Gupta A, Chatelain P, Massingham R, Jonsson EN, Hammarlund-Udenaes M. Brain distribution of cetirizine enantiomers: comparison of three different tissue-to-plasma partition coefficients: K(p), K(p,u), and K(p,uu). Drug Metab Dispos 2006; 34:318-23. [PMID: 16303872 DOI: 10.1124/dmd.105.007211] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objective of this study was to compare the blood-brain barrier (BBB) transport and brain distribution of levo- (R-CZE) and dextrocetirizine (S-CZE). Microdialysis probes, calibrated using retrodialysis by drug, were placed into the frontal cortex and right jugular vein of eight guinea pigs. Racemic CZE (2.7 mg/kg) was administered as a 60-min i.v. infusion. Unbound and total concentrations of the enantiomers were measured in blood and brain with liquid chromatography-tandem mass spectrometry. The brain distribution of the CZE enantiomers were compared using the parameters K(p,) K(p,u,) K(p,uu), and V(u,br). K(p) compares total brain concentration to total plasma concentration, K(p,u) compensates for binding in plasma, whereas K(p,uu) also compensates for binding within the brain tissue and directly quantifies the transport across the BBB. V(u,br) describes binding within the brain. The stereoselective brain distribution indicated by the K(p) of 0.22 and 0.04 for S- and R-CZE, respectively, was caused by different binding to plasma proteins. The transport of the CZE enantiomers across the BBB was not stereoselective, since the K(p,uu) was 0.17 and 0.14 (N.S.) for S- and R-CZE, respectively. The K(p,uu) values show that the enantiomers are effluxed to a large extent across the BBB. The V(u,br) of approximately 2.5 ml/g brain was also similar for both the enantiomers, and the value indicates high binding to brain tissue. Thus, when determining stereoselectivity in brain distribution, it is important to study all factors governing this distribution, binding in blood and brain, and the BBB equilibrium.
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Comparative Study |
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Snoeck E, Chanu P, Lavielle M, Jacqmin P, Jonsson EN, Jorga K, Goggin T, Grippo J, Jumbe NL, Frey N. A comprehensive hepatitis C viral kinetic model explaining cure. Clin Pharmacol Ther 2010; 87:706-13. [PMID: 20463660 DOI: 10.1038/clpt.2010.35] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We propose a model that characterizes and links the complexity and diversity of clinically observed hepatitis C viral kinetics to sustained virologic response (SVR)-the primary clinical end point of hepatitis C treatment, defined as an undetectable viral load at 24 weeks after completion of treatment)-in patients with chronic hepatitis C (CHC) who have received treatment with peginterferon alpha-2a +/- ribavirin. The new attributes of our hepatitis C viral kinetic model are (i) the implementation of a cure/viral eradication boundary, (ii) employment of all hepatitis C virus (HCV) RNA measurements, including those below the lower limit of quantification (LLOQ), and (iii) implementation of a population modeling approach. The model demonstrated excellent positive (99.3%) and negative (97.1%) predictive values for SVR as well as high sensitivity (96.6%) and specificity (99.4%). The proposed viral kinetic model provides a framework for mechanistic exploration of treatment outcome and permits evaluation of alternative CHC treatment options with the ultimate aim of developing and testing hypotheses for personalizing treatments in this disease.
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Journal Article |
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95 |
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Granados A, Jonsson E, Banta HD, Bero L, Bonair A, Cochet C, Freemantle N, Grilli R, Grimshaw J, Harvey E, Levi R, Marshall D, Oxman A, Pasart L, Räisänen V, Rius E, Espinas JA. EUR-ASSESS Project Subgroup Report on Dissemination and Impact. Int J Technol Assess Health Care 1997; 13:220-86. [PMID: 9194353 DOI: 10.1017/s0266462300010370] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The objective of health technology assessment (HTA) is to support decision making in health care. HTA does not claim to provide a definite solution to a health care problem, but to assist decision makers with evidence-based information about the clinical, ethical, social, and economic implications of the development, diffusion, and use of health care technology.
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Review |
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91 |
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Narbro K, Agren G, Jonsson E, Larsson B, Näslund I, Wedel H, Sjöström L. Sick leave and disability pension before and after treatment for obesity: a report from the Swedish Obese Subjects (SOS) study. Int J Obes (Lond) 1999; 23:619-24. [PMID: 10411235 DOI: 10.1038/sj.ijo.0800890] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVES To analyse sick leave and disability pension among surgically and conventionally treated obese patients. DESIGN A prospective study over five years. Differences in sick leave and disability pension were analysed using multiple and logistic regressions. Possible confounding factors were analysed and controlled for. SETTING Nine counties in Sweden. SUBJECTS 369 surgically treated patients and 371 matched obese controls, included in the Swedish Obese Subjects (SOS) study. At baseline, mean body mass index (BMI) was 42 kg/m2 in surgical patients and 41 kg/m2 in controls. After four years of treatment, weight reduction was 20% among surgical patients while the control patients kept their initial weight. INTERVENTION Gastric bariatric surgery. MEASUREMENTS Days of sick leave plus disability pension, and days of disability pension. RESULTS In the year prior to treatment, adjusted average number of days of sickness due to sick leave plus disability pension was similar in surgical patients and controls. Compared with controls, the surgical group had 35% more days of sickness during the first year after initiation of treatment, but 10-14% fewer days during years 2-3. During year four, days of sickness tended to be lower in the surgical group (P = 0.07). In the sub-group, aged above the median, surgical patients had 14-18% fewer days of sickness than controls, during years 2-3 after initiation of treatment This difference did not occur in the group below median age. CONCLUSION Surgical treatment of obesity results in a reduction of sick leave and disability pension, compared to controls, particularly in subjects aged 47-60 y.
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Comparative Study |
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Hamberg AK, Wadelius M, Lindh JD, Dahl ML, Padrini R, Deloukas P, Rane A, Jonsson EN. A pharmacometric model describing the relationship between warfarin dose and INR response with respect to variations in CYP2C9, VKORC1, and age. Clin Pharmacol Ther 2010; 87:727-34. [PMID: 20410877 DOI: 10.1038/clpt.2010.37] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objective of the study was to update a previous NONMEM model to describe the relationship between warfarin dose and international normalized ratio (INR) response, to decrease the dependence of the model on pharmacokinetic (PK) data, and to improve the characterization of rare genotype combinations. The effects of age and CYP2C9 genotype on S-warfarin clearance were estimated from high-quality PK data. Thereafter, a temporal dose-response (K-PD) model was developed from information on dose, INR, age, and CYP2C9 and VKORC1 genotype, with drug clearance as a covariate. Two transit compartment chains accounted for the delay between exposure and response. CYP2C9 genotype was identified as the single most important predictor of required dose, causing a difference of up to 4.2-fold in the maintenance dose. VKORC1 accounted for a difference of up to 2.1-fold in dose, and age reduced the dose requirement by ~6% per decade. This reformulated K-PD model decreases dependence on PK data and enables robust assessment of INR response and dose predictions, even in individuals with rare genotype combinations.
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Research Support, Non-U.S. Gov't |
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Lidbrink E, Elfving J, Frisell J, Jonsson E. Neglected aspects of false positive findings of mammography in breast cancer screening: analysis of false positive cases from the Stockholm trial. BMJ (CLINICAL RESEARCH ED.) 1996; 312:273-6. [PMID: 8611781 PMCID: PMC2349888 DOI: 10.1136/bmj.312.7026.273] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES To examine the implications of false positive results of mammography in terms of the time lag from screening and complete mammography to the point when women with false positive results are declared free of cancer; the extra examinations, biopsies, and check ups required; and the cost of these extra procedures. DESIGN Review of women with false positive results from the Stockholm mammography screening trial. SETTING Department of Oncology, South Hospital, Stockholm. SUBJECTS 352 and 150 women with false positive results of mammography from the first and second screening rounds of the Stockholm trial. MAIN OUTCOME MEASURES Extra examinations and investigations required and the cost of these procedures. RESULTS The 352 women from the first screening round made 1112 visits to the physician and had 397 fine needle aspiration biopsies, 187 mammograms, and 90 surgical biopsies before being declared free of cancer. After six months 64% of the women (219/342) were declared cancer free. The 150 women in the second round made 427 visits to the physician and had 145 fine needle aspiration biopsies, 70 mammograms, and 28 surgical biopsies, and after six months 73% (107/147) were declared cancer free. The follow up costs of the false positive screening results were Kr2.54m (250,000 pounds) in the first round and Kr0.85m (84,000 pounds) in the second round. Women under 50 accounted for about 41% of these costs. CONCLUSIONS The examinations and investigation carried out after false positive mammography --especially in women under 50--and the cost of these procedures are a neglected but substantial problem.
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research-article |
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Tunblad K, Jonsson EN, Hammarlund-Udenaes M. Morphine blood-brain barrier transport is influenced by probenecid co-administration. Pharm Res 2003; 20:618-23. [PMID: 12739770 DOI: 10.1023/a:1023250900462] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The objective of this study was to investigate the possible influence of probenecid on morphine transport across the blood-brain barrier (BBB) in rats. METHODS Microdialysis probes, calibrated using retrodialysis by drug, were placed into the striatum and jugular vein of seven Sprague-Dawley rats. Morphine was administered as a 4-h exponential infusion. The experiment was repeated the next day with the addition of probenecid, administered as a bolus dose (20 mg/kg) followed by a constant infusion (20 mg/kg/h). Models for BBB transport were built using the computer program NONMEM. RESULTS The steady-state ratio of 0.29 +/- 0.07 of unbound morphine concentration in brain to that in blood indicates that morphine is actively effluxed at the BBB. Probenecid co-administration increased the ratio to 0.39 +/- 0.04 (p < 0.05). Models in which probenecid influenced the brain efflux clearance rather than the influx clearance, well described the data. The half-life in brain increased from 58 +/- 9 min to 115 +/- 25 min when probenecid was co-administered. Systemic clearance of morphine also decreased upon probenecid co-administration, and M3G formation was decreased. CONCLUSION This study indicates that morphine is a substrate for the probenecid-sensitive transporters at the BBB. Co-administration of probenecid decreased the brain efflux clearance of morphine.
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Jonsson E, Fridborg H, Nygren P, Larsson R. Synergistic interactions of combinations of topotecan with standard drugs in primary cultures of human tumor cells from patients. Eur J Clin Pharmacol 1998; 54:509-14. [PMID: 9832291 DOI: 10.1007/s002280050505] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Combination therapies are important in the treatment of many tumor types. This study was undertaken to find candidates for combination therapy with the novel topoisomerase I inhibitor topotecan. METHODS The cytotoxic effect of topotecan alone and in combination with five standard cytotoxic drugs was studied in 27 primary cultures of human tumor cells from patients with various diagnoses using the fluorometric microculture cytotoxicity assay (FMCA). The combinations were analysed according to the multiplicative concept of drug interaction. RESULTS The additive model was shown to be a better descriptor than the effect of the most effective agent (Dmax) for all drug combinations tested. Topotecan in combination with cisplatin (CisP) was the drug combination showing synergy in the highest percentage of samples (54%), followed by topotecan in combination with doxorubicin (Dox: 39%), etoposide (P16; 23%), paclitaxel in the formulation Taxol (22%) and cytarabine (AraC; 12%). The high percentage of synergistic interactions was especially pronounced in solid tumors. In 28% of the samples tested, drug sensitivity testing of only single drugs failed to predict response to the drugs in combination. CONCLUSION Cisplatin and doxorubicin showed promising effects in combination with topotecan, and clinical trials with these combinations seem warranted. The results also indicate the value of testing drug combinations in in vitro drug sensitivity testing.
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Carroll J, Jonsson EN, Ebel R, Hartman MS, Holman TR, Crews P. Probing sponge-derived terpenoids for human 15-lipoxygenase inhibitors. J Org Chem 2001; 66:6847-51. [PMID: 11597201 DOI: 10.1021/jo015784t] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A human 15-lipoxygenase (15-HLO) assay has been employed to discover new marine-sponge-derived bioactive compounds. Extracts from two different sponges, Jaspis splendens (order Choristida, family Jaspidae) and Suberea sp. (order Verongida, family Aplysinellidae), exhibited potent IC(50) values of 0.4 and 0.1 microg/mL, respectively. Both are sources of terpenoids, and the former is a known source of (+)-jasplakinolide (7), which is inactive as a 15-HLO inhibitor. The terpenoids included (+)-(5S,6S)-subersin (1, IC(50) > 100 microM), (-)-(5R,10R)-subersic acid (2, IC(50) = 15 microM), jaspaquinol (3, IC(50) = 0.3 microM), and (-)-jaspic acid (4, IC(50) = 1.4 microM). Structure elucidations and lipoxygenase activity studies of these compounds are reported.
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Jonsson EN, Wade JR, Karlsson MO. Comparison of some practical sampling strategies for population pharmacokinetic studies. JOURNAL OF PHARMACOKINETICS AND BIOPHARMACEUTICS 1996; 24:245-63. [PMID: 8875349 DOI: 10.1007/bf02353491] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Using population analysis, sparsely sampled Phase 3 clinical data can be utilized to determine the pharmacokinetic characteristics of the target population. Data arising from such studies are likely to be constrained to certain sampling windows, i.e., the visiting hours at the study clinic. When the sampling window is narrow compared to the half-life of the drug, the advantage of taking more than one sample is not obvious. Study designs with one or two samples per visit have been compared with respect to (i) precision and bias of the population parameter estimates, (ii) the ability to identify the underlying pharmacokinetic model, and (iii) the estimation of individual parameter values. The first point was assessed using simulated data while the latter two were studied using a real data set. Results show: (i) Parameter estimates are more biased and imprecise when only one sample is taken compared to when two samples are obtained, this is true irrespective of the time span between the two samples. (ii) Ability to identify a more complex model is increased if two samples are taken. Specifically, the variability between occasions can be quantified. (iii) Two-sample designs are generally better with respect to prediction of individual parameter values. Even minor changes to commonly employed study designs, in this case the addition of one sample at each study occasion, can improve quality and quantity of the information obtained.
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Terént A, Marké LA, Asplund K, Norrving B, Jonsson E, Wester PO. Costs of stroke in Sweden. A national perspective. Stroke 1994; 25:2363-9. [PMID: 7974574 DOI: 10.1161/01.str.25.12.2363] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND PURPOSE Cost-effectiveness analyses of stroke management are hampered by paucity of economic data. We made an update of the direct and indirect costs of stroke in Sweden (population, 8.5 million). METHODS Direct costs (ie, the costs for hospital and outpatient care and social services) were estimated on the basis of two prospective population-based studies of stroke and of two nationwide cross-sectional inventories of bed-days and diagnoses. Indirect costs (ie, the costs for loss of productivity and early retirement) were based on official statistics. RESULTS The direct annual costs of care for stroke patients in 1991 equaled 7836 million Swedish krona (SKr) ($1306 million in US dollars), and the indirect costs, 2430 million SKr ($405 million). The cost of stroke care was 1208 SKr ($201) per inhabitant in Sweden. The expected direct costs per patient from first stroke to death were 440,000 SKr ($73,333). When prestroke costs for other diseases and advanced age were subtracted, the sum was reduced to 180,000 SKr ($30,000). CONCLUSIONS Costs for hospital and outpatient care and social services accounted for 76% of Swedish stroke costs and for 24% of costs for loss of production and early retirement. Only 41% of direct costs were stroke-related.
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