Log-Logistic Analysis of Herbicide Dose-Response Relationships

1995 ◽  
Vol 9 (2) ◽  
pp. 218-227 ◽  
Author(s):  
Steven S. Seefeldt ◽  
Jens Erik Jensen ◽  
E. Patrick Fuerst
Keyword(s):  
Dose Response ◽  
Logistic Model ◽  
Response Analysis ◽  
Analysis Method ◽  
Weed Science ◽  
Response Curves ◽  
Herbicide Resistant ◽  
Logistic Analysis ◽  
Analysis Methods ◽  
The Difference

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.

scholarly journals Nonmonotonic Pathway Gene Expression Analysis Reveals Oncogenic Role of p27/Kip1 at Intermediate Dose

2017 ◽  
Vol 16 ◽  
pp. 117693511774013 ◽  
Author(s):  
Hien H Nguyen ◽  
Susan C Tilton ◽  
Christopher J Kemp ◽  
Mingzhou Song
Keyword(s):  
Gene Expression ◽  
Pathway Analysis ◽  
Dose Response ◽  
Response Analysis ◽  
Response Curves ◽  
Cancer Pathways ◽  
Pathway Gene ◽  
Mechanistic Basis ◽  
Functional Pathway ◽  
Squamous Cell Papilloma

The mechanistic basis by which the level of p27Kip1 expression influences tumor aggressiveness and patient mortality remains unclear. To elucidate the competing tumor-suppressing and oncogenic effects of p27Kip1 on gene expression in tumors, we analyzed the transcriptomes of squamous cell papilloma derived from Cdkn1b nullizygous, heterozygous, and wild-type mice. We developed a novel functional pathway analysis method capable of testing directional and nonmonotonic dose response. This analysis can reveal potential causal relationships that might have been missed by other nondirectional pathway analysis methods. Applying this method to capture dose-response curves in papilloma gene expression data, we show that several known cancer pathways are dominated by low-high-low gene expression responses to increasing p27 gene doses. The oncogene cyclin D1, whose expression is elevated at an intermediate p27 dose, is the most responsive gene shared by these cancer pathways. Therefore, intermediate levels of p27 may promote cellular processes favoring tumorigenesis—strikingly consistent with the dominance of heterozygous mutations in CDKN1B seen in human cancers. Our findings shed new light on regulatory mechanisms for both pro- and anti-tumorigenic roles of p27Kip1. Functional pathway dose-response analysis provides a unique opportunity to uncover nonmonotonic patterns in biological systems.

Control of Volunteer Canola with Herbicides: Effects of Plant Growth Stage and Cold Acclimation

2006 ◽  
Vol 20 (2) ◽  
pp. 485-493 ◽  
Author(s):  
Anne Légère ◽  
Marie-Josée Simard ◽  
Eric Johnson ◽  
F. Craig Stevenson ◽  
Hugh Beckie ◽  
...  
Keyword(s):  
Cold Acclimation ◽  
Dose Response ◽  
Growth Stage ◽  
Field Experiments ◽  
Early Growth ◽  
Wheat Crop ◽  
Response Curves ◽  
Early Growth Stage ◽  
Herbicide Resistant ◽  
Phenoxy Herbicides

Phenoxy herbicides are frequently used to control volunteer canola populations. However, there have been claims that poor control could be due to cold acclimation of canola plants in the spring. The objective of this study was to determine whether cold acclimation or growth stage affected the response of canola volunteers to herbicides. In a growth room experiment, canola plants were prehardened and cold acclimated or were grown at 20/12 C and treated with one of six 2,4-D doses. Cold acclimation as achieved by this experiment affected upper and lower asymptotes of the dose–response curve but not the herbicide dose required to reduce canola weight by 50% relative to the nontreated control (GR50), indicating limited cold-related effects on canola tolerance to 2,4-D. Field experiments, conducted in the provinces of Québec and Saskatchewan, examined the effects of canola growth stage on the efficacy of 2,4-D, MCPA, and carfentrazone. Comparisons of the estimates from the dose–response curves confirmed that herbicide efficacy was consistently greater when canola plants were treated at an early growth stage, regardless of cultivar or herbicide used. The GR50estimates for canola plants treated at a later growth stage exceeded the recommended rates. Some canola plants grown as volunteers in a wheat crop survived 2,4-D or MCPA treatments at 0.5× and 1× rates and produced up to 148 seeds/m2. Efficient control of canola volunteers will be obtained when plants are sprayed at an early growth stage, but near-total control will be highly desirable in order to restrict seedbank buildup, particularly when dealing with canola cultivars with different herbicide-resistant traits.

scholarly journals Paraquat Resistance of Sumatran Fleabane (Conyza sumatrensis)

2019 ◽  
Vol 37 ◽  
Author(s):  
L.H.S. ZOBIOLE ◽  
V.G.C. PEREIRA ◽  
A.J.P. ALBRECHT ◽  
R.S. RUBIN ◽  
F.S. ADEGAS ◽  
...  
Keyword(s):  
Dose Response ◽  
Logistic Model ◽  
Multiple Resistance ◽  
Response Curves ◽  
Resistance Factors ◽  
First Case ◽  
Conyza Bonariensis ◽  
Western Area ◽  
Paraquat Resistance ◽  
Weed Resistance

ABSTRACT: In Brazil, some populations of Conyza bonariensis and C. canadensis are glyphosate resistant and there are populations of C. sumatrensis (Sumatran fleabane) presenting multiple resistance to both glyphosate and chlorimuron. During the 2014/2015 and 2015/2016 seasons, growers reported failures to control Sumatran fleabane with paraquat. This study investigated the potential of paraquat resistant Sumatran fleabane populations in Paraná state, Brazil. Populations with suspected paraquat resistance were tested in the field in 2016 season. In 2017, seeds from these populations were collected, sown and grown in a greenhouse. Paraquat dose-response curve experiments were performed in Mogi Mirim, SP; Londrina, PR and Palotina, PR using doses of 0, 50, 100, 200, 400, 800, 1,600 and 3,200 g ha-1, following all standard criteria for confirmation of weed resistance cases. Percentage control was assessed at 3, 7, 14, 21 and 28 days after application and data were fitted to a nonlinear, log-logistic model, and dose response curves were generated. The results of this study confirmed significant levels of resistance of Sumatran fleabane biotypes to paraquat with resistance factors between 3,57 to 34,29. Therefore, the first case of C. sumatrensis resistance to paraquat was confirmed in biotypes from the western area of Paraná state, Brazil.

In Vitro Phototoxicity Testing: Development and Validation of a New Concentration Response Analysis Software and Biostatistical Analyses Related to the Use of Various Prediction Models

2002 ◽  
Vol 30 (4) ◽  
pp. 415-432 ◽  
Author(s):  
Björn Peters ◽  
Hermann-Georg Holzhütter
Keyword(s):  
Prediction Models ◽  
Neutral Red ◽  
Response Analysis ◽  
Repeated Testing ◽  
Analysis Software ◽  
Response Curves ◽  
Photo Effect ◽  
The Difference

As demonstrated in several validation studies, the dermal phototoxic potential of chemicals in humans can be effectively assessed by in vitro methods. The core of these methods is to monitor dose–response curves of a chemical in the absence and presence of light, to quantify the difference between these two curves by appropriate measures (either the photo-irritancy factor [PIF], or the mean photo effect [MPE]), and to use these measures as predictors of in vivo phototoxicity. We present new concentration–response analysis software for in vitro phototoxicity testing, which runs on current personal computers, and takes into account all the limitations identified when using a former program. We also demonstrate the validity and robustness of this new software by applying it retrospectively to all data available from two phases of the EU/COLIPA validation trial for the 3T3 neutral red update in vitro phototoxicity test. Some frequently raised questions pertaining to the use of prediction models in phototoxicity testing are addressed, including: the necessity of using prediction models based on a cut-off; whether it is justifiable to use sharp prediction cut-off values; whether there is a biostatistical justification for the highest concentration of the test chemical; and whether repeated testing of a chemical is required.

scholarly journals Correlation of Chemical Analysis of Residual Levels of Aminocyclopyrachlor in Soil to Biological Responses of Alfalfa, Cotton, Soybean, and Sunflower

2011 ◽  
Vol 25 (2) ◽  
pp. 239-244 ◽  
Author(s):  
Stephen D. Strachan ◽  
Sergio C. Nanita ◽  
Marc Ruggiero ◽  
Mark S. Casini ◽  
Kathleen M. Heldreth ◽  
...  
Keyword(s):  
Dose Response ◽  
High Performance ◽  
Limit Of Detection ◽  
Soil Analysis ◽  
Plant Response ◽  
Response Analysis ◽  
Plant Responses ◽  
Response Curves ◽  
Additional Species ◽  
Rotational Crop

Researchers, product registration personnel, and growers desire the ability to chemically detect residual amounts of herbicides in soil at concentrations below those necessary to cause phytotoxicity to sensitive nontarget or rotational crop plants. Alfalfa, cotton, soybean, and sunflower, crops sensitive to low concentrations of aminocyclopyrachlor in soil, were planted at field test sites approximately 1 yr after aminocyclopyrachlor methyl was applied. Soil samples were collected when rotational crops were planted and were analyzed for aminocyclopyrachlor by a method based on high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS), with a limit of detection (LOD) of 0.1 part per billion (ppb) (soil oven-dry weight basis). Loglogistic dose–response analysis correlated visual phytotoxic plant responses to residual concentrations of aminocyclopyrachlor in the soil. Concentrations of aminocyclopyrachlor estimated to cause 25% phytotoxicity to alfalfa, cotton, soybean, and sunflower were 5.4, 3.2, 2.0, and 6.2 ppb, respectively, 20 to 60 times greater than the LOD of the analytical method available for soil analysis. Results from these studies suggest this HPLC/MS/MS method of analysis can be used to indicate potential risk and severity of plant response for alfalfa, cotton, soybean, and sunflower, and for other plant species once dose–response curves for these additional species are established. This chemical assay may be particularly important if researchers desire to study the concentration, movement, and dissipation of aminocyclopyrachlor in soil or as part of a forensic investigation to better understand the cause of an unanticipated or undesirable plant response.

Estimation of Dose–Response Models for Discrete and Continuous Data in Weed Science

2012 ◽  
Vol 26 (3) ◽  
pp. 587-601 ◽  
Author(s):  
William J. Price ◽  
Bahman Shafii ◽  
Steven S. Seefeldt
Keyword(s):  
Biological Sciences ◽  
Risk Assessment ◽  
Data Analysis ◽  
Least Squares ◽  
Dose Response ◽  
Least Squares Estimation ◽  
Continuous Data ◽  
Response Analysis ◽  
Weed Science ◽  
Response Models

Dose–response analysis is widely used in biological sciences and has application to a variety of risk assessment, bioassay, and calibration problems. In weed science, dose–response methodologies have typically relied on least squares estimation under the assumptions of normal, homoscedastic, and independent errors. Advances in computational abilities and available software, however, have given researchers more flexibility and choices for data analysis when these assumptions are not appropriate. This article will explore these techniques and demonstrate their use to provide researchers with an up-to-date set of tools necessary for analysis of dose–response problems. Demonstrations of the techniques are provided using a variety of data examples from weed science.

A Dose-Response Analysis of Nicotine Sensitization in Adolescent Rats D2-Primed as Neonates

2010 ◽  
Author(s):  
Elizabeth A. Hanchak ◽  
Meredith L. Smith ◽  
Jessie J. Smith ◽  
Marla K. Perna ◽  
Russell W. Brown
Keyword(s):  
Dose Response ◽  
Response Analysis ◽  
Adolescent Rats

ENCORE: A weight-based exacerbation dose response analysis of mepolizumab in severe asthma with eosinophilic phenotype

Pneumologie ◽  
2017 ◽  
Vol 71 (S 01) ◽  
pp. S1-S125
Author(s):  
I Pouliquen ◽  
D Austin ◽  
N Gunsoy ◽  
SW Yancey
Keyword(s):  
Severe Asthma ◽  
Dose Response ◽  
Response Analysis

Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

1974 ◽  
Vol 32 (02/03) ◽  
pp. 356-365 ◽  
Author(s):  
F Haverkate ◽  
D. W Traas
Keyword(s):  
Dose Response ◽  
Fibrinolytic Activity ◽  
Enzyme Concentration ◽  
Response Curves ◽  
Agar Gel ◽  
Porcine Tissue ◽  
Plate Assay ◽  
Fibrin Plate ◽  
Different Types ◽  
Dose Response Curves

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

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