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  • 1
    ISSN: 1432-1041
    Schlagwort(e): Key words Reference values ; Reference changes ; Phase I clinical trials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: Laboratory data are key evaluation procedures for Phase I clinical pharmacology for two reasons. Firstly, laboratory data are used within the screening process to exclude subjects with asymptomatic diseases, which could result in increased danger to themselves or confuse interpretation of the study results. Secondly, during study implementation, safety evaluation and in particular maximum tolerated dose determination have to be done by a case-by-case analysis, sometimes using laboratory adverse events (LAEs). Thus, relevant limits are needed to discriminate between a usual common variation and a significant abnormality, which is considered to be a LAE. This report presents laboratory data distribution, reference values and reference changes and, based on previously published new methods, suggests inclusion limits at screening and laboratory adverse event limits for analysis during study implementation. Subjects and methods: Nine hundred and twenty-seven young healthy male volunteers were recruited in one centre (Association de Recherche Thérapeutique). A standard screening process was carried out. Protocols were approved by the local ethics committee. Blood sampling was performed in the same conditions. Reference values (at screening and at baseline) were determined by a non-parametric procedure selecting 2.5% and 97.5% of the distribution of data. Reference changes were also defined as the 2.5–97.5% interval of distribution of the variations between the end of treatment and baseline. Inclusion limit and LAE limit methods of determination used had been specified in previous articles. Results: Detailed results of laboratory data distribution, reference values at screening and at baseline, reference changes, inclusion limits and LAE limits are presented in tables with number of subjects, mean, median, standard deviation, minimal and maximal values and the 2.5–97.5% interval for each laboratory parameter. Conclusion: The key aims of this paper are to provide clinical pharmacologists with data, reference values or changes obtained in the real conditions of Phase I study implementation, and to propose relevant limits, either for screening as inclusion limits, or during studies as LAE limits. Thus, these data, reference values and specific limits improve the capacity to screen healthy volunteers and to analyse LAEs during Phase I studies.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 52 (1997), S. 81-86 
    ISSN: 1432-1041
    Schlagwort(e): Key words Phase I study ; Adverse events; critical limits ; drug developments
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The first goal of phase I drug development is the determination of maximal tolerated dose, which must be established by case-by-case analysis, sometimes using a laboratory adverse event. Since no accurate rule defining lab adverse events, has been validated yet, we propose a new “combined method” based on combination of two thresholds: inclusion values and magnitude of variation. Using this combined method, the label “lab adverse event” is applied if any lab value exceeds the inclusion threshold and is associated with a variation from baseline exceeding the variation threshold defined from reference change limit. Thus, this study aimed to test this combined method on a large healthy volunteer population, studied in 19 phase I centres worldwide, and on five lab parameters: alanine amino transferase, aspartate amino transferase, alkaline phosphatases, creatinine and polymorphonuclear leukocytes. Methods: The inclusion threshold from each center was used. Reference change limits were defined from volunteers previously included in comparable studies and were expressed as absolute values: increases of 10 IU · l−1 for alanine amino transferase or aspartate amino transferase, 15 IU · l−1 for alkaline phosphatases, 15 μmol · l−1 for creatinine and a 0.34 109 · l−1 decrease for polymorphonuclear leukocytes. Comparison between the “combined method” and a normal range method was made using positive predictive value and a ratio between relevant and irrelevant results. This application was implemented in all young healthy volunteers (1134) included in 38 phase I studies sponsored by Rhône Poulenc Rorer from 1991 to 1993. Results: Seventy seven subjects (6.7%) were indicated in final study reports as having a lab adverse event (reference group). Of 179 subjects with lab abnormalities defined by the normal range method, 77 belonged to the reference group, inducing a poor 0.43 positive predictive value. Of ninety subjects with lab adverse events defined by the “combined method”, seventy-five belonged to the reference group, inducing a two-fold higher 0.83 positive predictive value. The combined method produced a high ratio of relevant/irrelevant results ( ) compared with the low ratio ( ) achieved using the normal range method. Conclusion: This new “combined method”, leading to a better definition of lab adverse event, seems an accurate and useful tool for routine case-by-case analysis within phase I drug development studies.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: Cross sections for stripping and dissociation of deuterons interacting with Be targets in the 100–2300 MeV energy range have been measured. Comparisons with model calculations suggest a dominant contribution of the stripping process. It is also shown that the deuteron break-up cross section exhibits the same energy dependence as the nucleon-nucleon cross section.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 12 (1999), S. 91-97 
    ISSN: 1434-6036
    Schlagwort(e): PACS. 82.70.Gg Gels and sols - 83.80.Jx Chemically reactive materials - 64.60.Ak Renormalization-group, fractal, and percolation studies of phase transitions - 02.70.Lq Monte-Carlo and statistical methods
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: 3d lattice Monte-Carlo simulations were done to obtain the mass distribution (N(m)) and pair correlation function (g(r)) of percolating clusters. We give analytical expressions of the external cut-off functions of N(m) at the z-average mass and of g(r) at the radius of gyration. The simulation results were compared with experimental results on gel forming systems reported in the literature. The comparison shows that the experimental results are compatible with the simulation results. However, more experiments are needed before we can be confident that the percolation model is a good model for the sol-gel transition.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 9 (1999), S. 83-91 
    ISSN: 1434-6036
    Schlagwort(e): PACS. 36.20.-r Macromolecules and polymer molecules - 61.10.-i X-ray diffraction and scattering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: Free radical co-polymerization of methyl methacrylate (MMA) and ethyl glycol dimethyl methacrylate (EGDMA) in solution leads to the formation of polydisperse branched PMMA which grows in size until the system gels. The structure and the size distribution of the PMMA aggregates were characterized at infinite dilution using static and dynamic light scattering and size exclusion chromatography (SEC). The reaction extent was measured using SEC and Raman spectroscopy. The results show that the structure and size distribution of PMMA aggregates formed close to the gel point are compatible with those of percolating clusters. The structure factor of semi-dilute solutions of PMMA aggregates is the same as that of dilute solutions at distance scales much smaller than the correlation length of the concentration fluctuations ( ). However, the cut-off function of the pair correlation function at for semi-dilute solutions is more gradual than the cut-off function at for dilute solutions.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 14 (1997), S. 1275-1277 
    ISSN: 1573-904X
    Schlagwort(e): X-ray scattering ; human stratum corneum ; electroporation, high voltage pulses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of sol gel science and technology 15 (1999), S. 129-136 
    ISSN: 1573-4846
    Schlagwort(e): simulation ; percolation ; aggregation ; structure ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Three-dimensional (3D) Monte Carlo simulations of diffusion limited cluster aggregation at different concentrations (φ) show a crossover from a flocculation regime at short times to a percolation regime close to the gel time (tg). Contrary to suggestions in the literature tg is independent of the system size (L) for large L. The structural and temporal crossovers between flocculation and percolation take place at characteristic values of the cluster mass (mc) and the time (tc) which depend on φ. After normalisation by these characteristic values the crossovers are independent of φ except for very small clusters and at short times. The concentration dependence of mc and tc indicates that the crossover takes place at a given cumulated volume fraction of the clusters independent of φ. At low concentrations the φ-dependence of tg is determined by the cluster growth in the flocculation regime.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 9 (1999), S. 71-82 
    ISSN: 1434-6036
    Schlagwort(e): PACS. 36.20.-r Macromolecules and polymer molecules - 61.10.-i X-ray diffraction and scattering - 82.70.Gg Gels and sols
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: Free radical co-polymerization of methyl methacrylate (MMA) and ethyl glycol dimethyl metacrylate (EGDMA) was investigated in solution at different molar ratios R = [EGDMA]/[MMA] between 0 and 0.05. Initially mainly linear PMMA was formed with weight average molar mass 7.5 g/mol independent of R. At larger reaction extents branched polymers were formed and the systems gelled. The scattering intensity rose initially with the reaction extent, but reached a plateau value at larger reaction extents. The plateau value increased strongly with R. Dynamic light scattering showed the appearance of a slow relaxation not observed in linear PMMA solutions. The data can be interpreted by assuming that the excess scattering originates from the branching points and relaxes through self diffusion of the branched particles. The results agree with predictions of the percolation model for gelation and Rouse dynamics. Viscosity measurements corroborate this interpretation. Measurements on a progressively diluted sample quenched close to the gel point again showed quantitative agreement with the percolation model for gelation.
    Materialart: Digitale Medien
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