In this paper, the authors describe fractional polynomials and cubic splines with which to represent smooth dose-response relations in summarizing meta-analytical aggregate data. Use of these two curve-fitting families can help prevent the problems arising from inappropriate linearity assumptions. These methods are illustrated in the problem of estimating the shape of the dose-response curve be...

some areas of ramsar, a city in northern iran are among the world’s wellknown inhabited areas with highest levels of natural radiation. annual exposure levels in these areas are up to 260 mgy y‐1 and the mean exposure rate is about 10 mgy y‐1 for a population of about 2000 residents. if elevated levels of natural radiation as high as a few hundred msv per year is detrimental to health and leads...

The utility of a biological dosimeter based on the analysis of dicentrics is invaluable in the event of a radiological emergency wherein the estimated absorbed dose of an exposed individual is crucial in the proper medical management of patients. The technique is also used for routine monitoring of occupationally exposed workers to determine radiation exposure. An in vitro irradiation study of ...

It is well known that a-adrenoceptors have been classified into the a1-type in postsynaptic sites and the a2-type in presynaptic sites (1). Prazosin and yohimbine are selective an tagonists of a1 and a2-adrenoceptors, re spectively (2). Norepinephrine (NE) exerts a non-selective agonistic action at each type of a-adrenoceptors (3, 4). Recent reports present evidence that postsynaptic a2 as well...

Introduction: One of the protective concepts in the interpretation of radiation damage in radiobiology is the radioadaptive response. The objective of this present report is to evaluate the induction of radioadaptive response in male rats by injection of pre-irradiated serum with low doses X-radiation intraperitoneally.   Materials and Methods: 80 male adul...

The value of determining the slope of the histamine dose-response curve, in addition to the histamine provocation concentration producing a 20% reduction in FEV1 (PC20-FEV1), was assessed by analysis of histamine dose-response curves in 40 patients selected as having a wide range of increased non-specific bronchial responsiveness to inhaled histamine. The histamine dose-response curves were fou...

In normal subjects in vivo the dose-response curve to inhaled nonsensitizing stimuli reaches a plateau at mild degrees of airway narrowing. We investigated whether the limitation of the response is due to non-optimal smooth muscle activation, by administering high doses of histamine and methacholine together. In fifteen normal subjects a complete dose-response curve to methacholine was recorded...

The half-maximal inhibitory concentration IC[Formula: see text] is an important pharmacodynamic index of drug effectiveness. To estimate this value, the dose response relationship needs to be established, which is generally achieved by fitting monotonic sigmoidal models. However, recent studies on Human Immunodeficiency Virus (HIV) mutants developing resistance to antiviral drugs show that the ...