Table 1

Total and human DNA yields (μg/two cytobrushes or μg/one 10-ml mouthwash sample) from phase 1 of the study by method of collection and DNA extraction

Method of collection DNA extractionNSpectrophotometryHybridization
Total DNA yieldA260 nm:A280 nmHuman DNA yield
Median(range)Median(range)Median(range)
Cytobrushesa
 Phenol-chloroform4013.6bc(2.2–43.5)1.9(1.6–2.1)1.0def(0.006–13.5)
 QIAamp kit408.8c(1.5–28.6)1.7(1.4–1.9)0.4e(0.006–19.0)
 NaOH40126.0(7.6–396.7)1.3(1.2–2.2)1.3f(0.006–20.5)
Mouthwashg
 Phenol-chloroform3557.3bhi(10.8–286.9)1.9(1.7–2.0)27.5dik(3.1–293.5)
 QIAamp kit3035.2h(10.5–90.6)1.8(1.7–2.1)10.6j(1.5–79.9)
 Puregene kit2052.5i(10.6–199.2)1.9(1.7–1.9)28.5k(6.2–243.3)
  • a Each DNA extraction arm includes 40 cytobrush samples from a total of 120 women participating in the WHS (i.e., independent observations in each arm).

  • b P < 0.001, cytobrush phenol-chloroform versus mouthwash phenol-chloroform, Wilcoxon’s rank-sum test.

  • c P = 0.008, cytobrush phenol-chloroform versus cytobrush QIAamp kit, Wilcoxon’s rank-sum test.

  • d P < 0.001, cytobrush phenol-chloroform versus mouthwash phenol-chloroform, Wilcoxon’s rank-sum test.

  • e P = 0.005, cytobrush phenol-chloroform versus cytobrush QIAamp kit, Wilcoxon’s rank-sum test.

  • f P = 0.97, cytobrush phenol-chloroform versus cytobrush NaOH, Wilcoxon’s rank-sum test.

  • g Each DNA extraction arm includes one of three aliquots of equal volume made from single mouthwash samples collected from a total of 40 men participating in the AHS (i.e., paired observations in each arm).

  • h P < 0.001, mouthwash phenol-chloroform versus mouthwash QIAamp kit (N = 25 pairs), Wilcoxon’s sign-rank tests for matched pairs.

  • i P = 0.22, mouthwash phenol-chloroform versus mouthwash Puregene kit (N = 20 pairs), Wilcoxon’s sign-rank tests for matched pairs.

  • j P < 0.001, mouthwash phenol-chloroform versus mouthwash QIAamp kit (N = 25 pairs), Wilcoxon’s sign-rank tests for matched pairs.

  • k P = 0.83, mouthwash phenol-chloroform versus mouthwash Puregene kit (N = 20 pairs), Wilcoxon’s sign-rank tests for matched pairs.