The comparison of predicted RNA/RNA stabilities with those measured for 2 0 -O-methyl RNA/RNA duplexes suggests that the INN-HB model will also be applicable to 2 0 -O-methyl RNA/RNA duplexes (71) . The results in Tables 1 and 2 Table 4 ). Three nearest neighbors are only represented once or twice in the database, and these parameters are in parentheses. The parameters for 2 0 -O-methyl RNA/RNA and RNA/RNA duplexes are similar, especially if the RNA/RNA Watson-Crick nearest-neighbor parameters are each made less favorable by 0.12 kcal/mol, which largely accounts for the difference in salt concentration as suggested above. Evidently, the first term on the right hand side of Equation 1 can also be approximated by: Table 3 compares predictions from combining Equations 1 and  4 with measured values for duplexes with more than one LNA. The root-mean-square difference between measured and predicted DG 37 values is 0.6 kcal/mol with the largest difference being the 1.7 kcal/mol associated with the duplex containing a 5 0 G M U L /3 0 CA nearest neighbor. Undoubtedly, this model can be expanded and refined by more measurements, but it appears sufficient to aid sequence design for many applications.