MPV (version 1.64)

lesions: Lesions in Rat Colons

Description

Numbers of aberrant crypt foci (ACF) in each of six cross-sectional regions of the colons of 66 rats subjected to varying doses of the carcinogen azoxymethane (AOM), sacrificed at 3 different times.

Usage

lesions

Format

This data frame contains the following columns:

T

Incubation time factor, levels: 6, 12 and 18 weeks

INJ

Number of injections

SECT

Section of colon, a factor with levels 1 through 6, where 1 denotes the proximal end of the colon and 6 denotes the distal end

RAT

Label for animal within a particular T-INJ factor level combination

ACF.Total

Total number of ACF lesions in a section of a rat's colon

ACF.total.mult

Sum of ACF multiplicities for a section of a rat's colon

id

Identifier for each of the 66 rats.

References

E.A. McLellan, A. Medline and R.P. Bird. Dose response and proliferative characteristics of aberrant crypt foci: putative preneoplastic lesions in rat colon. Carcinogenesis, 12(11): 2093-2098, 1991.

Examples

summary(lesions)
ACF.All <- aggregate(ACF.Total ~  id + INJ + T, FUN=sum, data = lesions)
lesions.glm <- glm(ACF.Total ~ INJ * T, data = ACF.All, family=poisson)
summary(lesions.glm)
lesions.qp <- glm(ACF.Total ~ INJ * T, data = ACF.All, family=quasipoisson)
summary(lesions.qp)
lesions.noInt <- glm(ACF.Total ~ INJ + T, data = ACF.All, family=quasipoisson)
summary(lesions.noInt)