Biomaterial Database

Testing the mutagenic potency of chemical substances in a linear host-mediated assay (LIHMA). 1977

R J Lorenz, and J Vollmar, and A Grafe

Instead of comparing "mutation frequencies" as used in the conventional host-mediated assay (HMA), a modified concept of measuring mutagenic potency is introduced by using a number of time intervals for taking samples. Regression analysis methods can then be applied to the numbers of mutant bacteria (reversions). Not only the mutagenic but also an additional antibacterial potency of a compound can be detected and estimated in the sam assay. It is demonstrated that interference of (undetected) antibacterial activity with the mutagenic activity may lead to misclassification of a substance concening its mutagenicity in the conventional HMA. This kind of erroneous assessment will be avoided by the LIHMA. Another advantage of the LIHMA over the conventiona HMA is that regression analysis also allows estimation of the sensitivity and reliability of the assay. The calculative procedure may be programmed on desk computers and is then most suitable for laboratories where large numbers of substances have to be examined routinely. A numerical is given using results obtained with nitrosoguanidine.

UI	MeSH Term	Description	Entries
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009153	Mutagens	Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.	Clastogen,Clastogens,Genotoxin,Genotoxins,Mutagen
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D012044	Regression Analysis	Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.	Regression Diagnostics,Statistical Regression,Analysis, Regression,Analyses, Regression,Diagnostics, Regression,Regression Analyses,Regression, Statistical,Regressions, Statistical,Statistical Regressions
D005787	Gene Frequency	The proportion of one particular in the total of all ALLELES for one genetic locus in a breeding POPULATION.	Allele Frequency,Genetic Equilibrium,Equilibrium, Genetic,Allele Frequencies,Frequencies, Allele,Frequencies, Gene,Frequency, Allele,Frequency, Gene,Gene Frequencies
D005821	Genetic Techniques	Chromosomal, biochemical, intracellular, and other methods used in the study of genetics.	Genetic Technic,Genetic Technics,Genetic Technique,Technic, Genetic,Technics, Genetic,Technique, Genetic,Techniques, Genetic
D001431	Bacteriological Techniques	Techniques used in studying bacteria.	Bacteriologic Technic,Bacteriologic Technics,Bacteriologic Techniques,Bacteriological Technique,Technic, Bacteriological,Technics, Bacteriological,Technique, Bacteriological,Techniques, Bacteriological,Bacteriologic Technique,Bacteriological Technic,Bacteriological Technics,Technic, Bacteriologic,Technics, Bacteriologic,Technique, Bacteriologic,Techniques, Bacteriologic
D013223	Statistics as Topic	Works about the science and art of collecting, summarizing, and analyzing data that are subject to random variation.	Area Analysis,Estimation Technics,Estimation Techniques,Indirect Estimation Technics,Indirect Estimation Techniques,Multiple Classification Analysis,Service Statistics,Statistical Study,Statistics, Service,Tables and Charts as Topic,Analyses, Area,Analyses, Multiple Classification,Area Analyses,Classification Analyses, Multiple,Classification Analysis, Multiple,Estimation Technic, Indirect,Estimation Technics, Indirect,Estimation Technique,Estimation Technique, Indirect,Estimation Techniques, Indirect,Indirect Estimation Technic,Indirect Estimation Technique,Multiple Classification Analyses,Statistical Studies,Studies, Statistical,Study, Statistical,Technic, Indirect Estimation,Technics, Estimation,Technics, Indirect Estimation,Technique, Estimation,Technique, Indirect Estimation,Techniques, Estimation,Techniques, Indirect Estimation
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor