lesions {MPV}

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.

Source

Ranjana P. Bird, University of Northern British Columbia, Prince George, Canada.

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)