Table 1.

Semi-quantitative light microscopic analysis of heart sections from 13- or 26-week-old female CD-1 mice exposed transplacentally to 3TC, AZT, or AZT/3TC

Treatment group	Group sizes	Mean score ± SE at 13 weeks	Mean score ± SE at 26 weeks	Comparisons of values at 13- versus 26-weeks-of-age (P-value)
Control	n = 4	0.25 ± 0.39	0 ± 0	P > 0.05
3TC	n = 4	3.00 ± 0.39	1.25 ± 0.39	P < 0.01*
AZT	n = 8	2.38 ± 0.29	1.38 ± 0.28	P = 0.01*
AZT/3TC	n = 8	3.50 ± 0.28	2.25 ± 0.28	P < 0.01*
Comparisons of NRTI treatment groups versus controls (P-value)		3TC, P < 0.001*	3TC, P = 0.039*
		AZT, P < 0.001*	AZT, P = 0.01*
		AZT/3TC, P < 0.001*	AZT/3TC, P < 0.001*
Comparisons of individual NRTI treatment groups (P-value)		3TC vs AZT, P = 0.05	3TC vs AZT,
		3TC vs AZT/3TC, P > 0.05	P > 0.05 3TC vs AZT/3TC,
		AZT vs AZT/3TC, P = 0.011*	P = 0.013* AZT vs AZT/3TC,
			P = 0.017*

Ten-micrometer heart sections were stained with Masson's trichrome, a section from each mouse (number of mice listed in table, number of litters examined: vehicle = 4, 3TC = 3, AZT = 6, AZT/3TC = 5) was scored based upon the percentage of cardiomyocytes affected, and the values were averaged across the group to get an average ± standard error. The semi-quantitative scoring scheme was as follows: (0), within normal limits, ≤5% of cells affected; (1+) mild, 6–20% of cells affected, (2+) moderate, 21–50% of cells affected, (3+), marked, 51–80% of cells affected; (4+) severe, >80% of cells affected. P-values for comparison of differences among the exposure groups were obtained using a two-way ANOVA with a Holm-Sidak post hoc test. The treatment-related data from 13- and 26-week-old mice were significantly different (P = 0.05)

^*Significant P-values