Curve dose effect

Similar to alcohol and other CNS depressants, toluene has a biphasic dose-effect curve for the motor activity of rodents (Hinman 1987 Riegel and... 

These results, however, cannot be used to establish a dose-effect curve, because of inadequate dose estimates. For this purpose it is necessary to calculate the individual accumulated external and internal doses of all persons involved into the investigation,... 

Very often, the dose-effect curve is redrawn using a logarithmic scale for the dose. This gives rise to a sigmoid curve, as shown in Fig. 5.2. It is a mathematical transformation, which shows an approximate linear portion for the 20-80% maximal effect scale, which is usually the dose level for a therapeutic drug. Doses above 80% provide very little increase in therapeutic effects but with a concomitant rise in the risk of adverse reactions. 

This indicates that the dose-effect curve is quite... 

Several overall conclusions can be drawn based on the statistical evaluation of the data submitted by the participants of the DR CALUX intra-and interlaboratory validation study. First, differences in expertise between the laboratories are apparent based on the results for the calibration curves (both for the curves as provided by the coordinator and for the curves that were prepared by the participants) and on the differences in individual measurement variability. Second, the average results, over all participants, are very close to the true concentration, expressed in DR CALUX 2,3,7,8-TCDD TEQs for the analytical samples. Furthermore, the interlaboratory variation for the different sample types can be regarded as estimates for the method variability. The analytical method variability is estimated to be 10.5% for analytical samples and 22.0% for sediment extracts. Finally, responses appear dependent on the dilution of the final solution to be measured. This is hypothesized to be due to differences in dose-effect curves for different dioxin responsive element-active substances. For 2,3,7,8-TCDD, this effect is not observed. Overall, based on bioassay characteristics presented here and harmonized quality criteria published elsewhere (Behnisch et al., 2001a), the DR CALUX bioassay is regarded as an accurate and reliable tool for intensive monitoring of coastal sediments. 

Dose-Effect Curves Demonstrate the relation between dose and the magnitude of a graded effect, eidier in an individual or in a population. Such curves may have a variety of forms. Within a given dose range they may be linear but more often they are not. 

The quantal dose-effect curve is often characterized by stating the median effective dose (ED50), which is the dose at which 50% of individuals exhibit the specified quantal effect. (Note that the abbreviation ED50 has a different meaning in this context... 

Finally, note that the quantal dose-effect curve and the graded dose-response curve summarize somewhat different sets of information, although both appear sigmoid in shape on a semilogarithmic plot (compare Figures 2-15 and 2-16). Critical... 

For example, the industrial chemical hydrazine not only causes death, as a result of effects on the central nervous system, but also causes dysfunction in the liver, leading to the accumulation of fat. This effect is not related to the lethality, but it shows a clear relationship with dose. The response, that is, fatty liver, is a graded effect rather than an all-or-none response and can be quantitated either as an increase in liver weight (as percent of body weight) or by specific measurement of the triglycerides. Both measurements show a similar dose-effect curve (Fig. 2.2). 

This expression makes it possible to use dose effect curves to give both target number (m), related to the shoulder on sigmoid curves, and target size (v), related to the final exponential slope. 

Fig. 4.6 (A and B) Dependence of the drug-induced reduction of the transition temperature (A 7",) on the amount of chlorphentermine and clofibric acid added. The dissociation equilibrium of the drugs was shifted to the indicated forms by adjusting the pH of the liposome suspension to pH 6 and over pH 9 respectively (A). Dose-effect curves of the uncharged forms (pH 10 and pH 4.5, respectively. Dotted line indicates drug amounts at which morphologic alterations occurred in the liposome suspension (B). (Reprinted from Fig. 2 of ref. 96 with permission from Elsevier Science). (C) Liposomal binding of chlorphentermine and clofibric acid depending on the total amount of drug added to the liposome suspension (mean values of triplicate determinations). Maximum deviation from the mean was 10% of the mean. (Reprinted from Fig. 3 of ref. 96 with permission from Elsevier Science)...

Tolerance develops rapidly following acute or chronic treatment with peptidic or nonpeptidic delta agonists [67-71]. For example, Figure 3 shows dose-effect curves for SNC80 administered alone or 24 h after pretreatment with SNC80 (1.0-10 mg/kg) in an assay of schedule-controlled responding for food reinforcement in rhesus monkeys [71]. Under control conditions, SNC80... 

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