Duk-Chul Lee, et al. Statistical analysis Data are expressed as means ± SD. Clinical characteristics were compared between the HT and the non-HT groups using t-tests for the continuous variables and Pearson chi-squares ( 2) for the categorical variables. CT value differences were compared between the HT and the non-HT groups using t-tests. Relative T/S ratios were compared between the two groups using the Wilcoxon rank sum test because the distributions were skewed. Multivariate linear regression an- alyses were performed to determine the associa- tion of HT and log2 values of relative T/S ratios (ΔΔCT) after adjusting for potential confounding factors. All data were analyzed using the statis- tical program SAS 8.01 (SAS Institute, Cary, NC, USA). RESULTS Clinical characteristics of study subjects Clinical characteristics are shown in Table 1. Mean ages of the study subjects were 60.1 ± 3.5 years for the HT group and 60.3 ± 4.4 years for the non-HT group with no statistical difference. No statistical differences were found between the two groups with regards to age, age at meno- pause, blood pressure, cholesterol, triglyceride, LDL-cholesterol, TAS, and hs-CRP levels. Serum fasting glucose levels were significantly higher in the non-HT group than in the HT group (p < 0.0001), but HDL-cholesterol levels were notably higher in the HT group than in the non-HT group Yonsei Med J Vol. 46, No. 4, 2005 Fig. 1. Agarose gel electrophoresis following telo- mere PCR. Each 20μl aliquot of the PCR product was loaded onto prepared 4% metaphor agarose gels in 45 mM tris borate and 1 mM EDTA with ethidium bromide. The gel was run at 50 V for one hr and visualized and photographed under UV illumination. Lanes 1 and 6, size marker; lane 2, DNA without telomere primers; lane 3, telomere primers without DNA; lanes 4 and 5, human DNA with telomere primers. The bottom of the smear in lanes 4 and 5 was estimated to contain a 78 bp telomere product. (p < 0.001). Mean (± SD) serum estradiol levels of the HT group were 35.6 (± 35.5) pg/L, which were significantly higher than those in the non- HT group (p < 0.0001). Women who participated in regular exercise or took daily vitamins were better represented in the HT group (p < 0.01 and p < 0.01, respectively) than in the non-HT group. Comparison of relative T/ S ratios CT values of telomere PCR in the HT group were significantly lower than those in the non-HT group (p < 0.05). That is, the HT group had a greater amount of telomeres than the non-HT group because the total amount of telomeres in a DNA sample was approximately 2-CT (telomere). ΔCT values. were calculated by subtracting the β globulin (single copy gene) CT value from the telomere CT value, which was also significantly lower in the HT group than in the non-HT group (p<0.01)(Table 2). The HT group had greater T/S ratios than the non-HT group of postmenopausal women because the T/S ratio in a DNA sample was approximately {2CT (telomere)/2CT (β-globin)}-1= 2-Δ CT. Relative T/S ratios of study subjects to a reference (a healthy young female) were greater in the HT group than in the non-HT group (p < 0.01) (Table 3). In other words, telomere lengths were longer in the HT group than in the non-HT group of postmenopausal women. Because serum fasting glucose levels, HDL cholesterol levels, and the prevalence of regular exercise and daily vitamin use statistically differed between the two groups, and also because several potential confounding factors known to be related to telomere length existed in this study, a multiple