Results Of Dose-response Studies Research Articles

Dose–response studies of fluticasone propionate and budesonide: Classification based on asthma severity

There are discrepancies in the results of dose-response studies of inhaled steroids. Although some studies show a dose-response relationship, others show no change in outcome with increasing the dose of inhaled steroids. These discrepancies are partly caused by the heterogeneity of dose-response studies. One area of heterogeneity is the subjects' level of asthma severity at baseline. The objective of this study was to classify dose-response studies of two widely used inhaled steroids for asthma, fluticasone propionate (FP), and budesonide (BUD), according to the subjects' level of asthma severity at baseline. A PubMed search, limited to the English language and human subjects, was conducted from January of 1983 to January of 2004, using "dose response and budesonide" (331 articles) and "dose-response and fluticasone" (211 articles). Bibliographies of selected articles were searched for more references. Articles with at least two doses of the same inhaled steroid and one objective marker of asthma were included, resulting in 29 articles for FP and 32 articles for BUD. Studies vary widely in their assessment and reporting of indicators of asthma severity and control at baseline but could be classified according to the level of steroid use at baseline as an indicator of asthma severity. Studies with all or some patients on oral steroids at baseline consistently showed a dose response. Although heterogeneity of dose-response studies make their classification and interpretation difficult, a dose response was consistently noted when all or some patients were on oral steroids at baseline.

Log-Logistic Analysis of Herbicide Dose-Response Relationships

Dose-response studies are an important tool in weed science. The use of such studies has become especially prevalent following the widespread development of herbicide resistant weeds. In the past, analyses of dose-response studies have utilized various types of transformations and equations which can be validated with several statistical techniques. Most dose-response analysis methods 1) do not accurately describe data at the extremes of doses and 2) do not provide a proper statistical test for the difference(s) between two or more dose-response curves. Consequently, results of dose-response studies are analyzed and reported in a great variety of ways, and comparison of results among various researchers is not possible. The objective of this paper is to review the principles involved in dose-response research and explain the log-logistic analysis of herbicide dose-response relationships. In this paper the log-logistic model is illustrated using a nonlinear computer analysis of experimental data. The log-logistic model is an appropriate method for analyzing most dose-response studies. This model has been used widely and successfully in weed science for many years in Europe. The log-logistic model possesses several clear advantages over other analysis methods and the authors suggest that it should be widely adopted as a standard herbicide dose-response analysis method.

Inhibition of Ca2+ and K+ currents by "antifreeze" proteins.

For the last two decades, the research on fish "antifreeze" proteins has focused exclusively on their ability to depress noncolligatively blood plasma freezing points, presumably by binding to ice crystals. We report evidence that antifreeze polypeptides from the winter flounder (Pseudopleuronectes americanus) have another special property, the ability to block ion channels. In experiments with porcine granulosa cells we show, using the patch-clamp technique in the whole cell configuration, that these proteins suppress effectively calcium and potassium currents. The results of dose-response studies indicate a protein-protein interaction mechanism.

In Vitro Effect of Lithium on Carbamazepine-Induced Inhibition of Murine and Human Bone Marrow-Derived Granulocyte-Macrophage, Erythroid, and Megakaryocyte Progenitor Stem Cells

Lithium (Li) is a known agent capable of producing leukocytosis, first observed in manic depressive patients receiving Li as therapy; however, a certain percentage of cases are nonresponsive to Li therapy. These patients are responsive to carbamazepine (CBZ); however, severe hematopoietic side effects have been associated with CBZ treatment such as leukopenia. We report here the results of dose-response studies (0.1-100 micrograms/ml) that demonstrate CBZ treatment inhibits both murine and human bone marrow-derived granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and megakaryocyte progenitor (CFU-Meg) cells. The addition of Li prior to and simultaneously with CBZ to marrow cultures was effective in reversing the CBZ-induced toxicity only in the presence of an optimal Li dose (1.0 mM) known to stimulate bone marrow function. However, when the addition of Li was delayed 24 hr to CBZ-treated cultures no protective effect was observed for any marrow progenitor. Thus, the time of Li-CBZ exposure is critical to observe the protective effect of Li. These results demonstrate that the leukopenia associated with CBZ treatment may be due to the ability of CBZ to inhibit marrow progenitor cells and suggest Li may be an effective agent to reverse the marrow toxic effects of CBZ.