(A and B) One group of HO mice was maintained on 2% betaine water for 18 days (Betaine, n = 5); the second group (Betaine + PEGC15S, n = 5) received the same treatment, but they received 2 injections of 7.5 mg/kg PEGC15S on days 14 and 15. The third group of mice (PEGC15S, n = 5) was maintained on normal water and received 2 injections of 7.5 mg/kg htCBS C15S on days 14 and 15. tHcy and cystathionine levels in these groups were determined on day 0 and on days 14–18. Data are presented as the mean ± SEM and were analyzed using ANOVA, followed by Tukey’s post-hoc test. *P ≤ 0.05, **P ≤ 0.01, and ***P ≤ 0.001.