Confirmation of associations between ion channel gene SNPs and QTc interval duration in healthy subjects.

Population-based association studies have identified several polymorphic variants in genes encoding ion channel subunits associated with the electrocardiographic heart-rate-corrected QT (QTc) length in healthy populations of Caucasian origin (KCNH2 rs1,805,123 (K897 T) and rs3,815,459, SCN5A rs1,805,126 (D1,819D), 1,141-3 C>A, rs1,805,124 (H558R), and IVS24+116 G>A, KCNQ1 rs757,092, KCNE1 IVS2-128 G>A and rs1,805,127 (G38S), and KCNE2 rs2,234,916 (T8A)). However, few of these results have been replicated in independent populations. We tested the association of SNPs KCNQ1 rs757,092, KCNH2 rs3,815,459, SCN5A IVS24+116 G>A, KCNE1 IVS2-128 G>A and KCNE2 rs2,234,916 with QTc length in two groups of 200 subjects presenting the shortest and the longest QTc from a cohort of 2,008 healthy subjects. All polymorphisms were in Hardy-Weinberg equilibrium in both groups. The minor allele SCN5A IVS24+116 A was more frequent in the group of subjects with the shortest QTc, whereas the minor alleles KCNQ1 rs757,092 G and KCNH2 rs3,815,459 A were more frequent in the group with the longest QTc. There was no significant difference for KCNE1 IVS2-128 G>A and KCNE2 rs2,234,916 between the two groups. Haplotype analysis showed a twofold increased risk of QTc lengthening for carriers of the haplotype, combining alleles C and A of the two common KCNE1 SNPs, IVS2-129 C>T (rs2,236,609) and rs1,805,127 (G38S), respectively. In conclusion, our study confirms the reported associations between QTc length and KCNQ1 rs757,092 and KCNH2 rs3,815,459.

Partial pressures and nature of products. Application to the photolysis of PH3 and NH3 in the atmosphere of Jupiter and Saturn.

The photolysis of mixtures of gases containing NH3 or PH3 presents important differences mainly due to the strength of the X-H bond. On some examples, these differences are evidenced and the consequences for mixtures of gases containing these two compounds are shown: the photolysis of ammonia and ethylene mainly gives ethyl-, butyl- and hexylamine whereas the photolysis of phosphine and ethylene leads to ethyl- and vinylphosphine. When gaseous mixtures of NH3, PH3 and ethylene are photolyzed together, the presence of phosphine dramatically decreases the formation of nitrogen derivatives. The relevance of such lab studies to the atmospheres of Jupiter and Saturn is discussed.

Acidity trends in alpha,beta-unsaturated alkanes, silanes, germanes, and stannanes.

The gas-phase acidity of ethyl-, vinyl-, ethynyl-, and phenyl-substituted silanes, germanes, and stannanes has been measured by means of FT-ICR techniques. The effect of unsaturation on the intrinsic acidity of these compounds and the corresponding hydrocarbons was analyzed through the use of G2 ab initio and DFT calculations. In this way, it was possible to get a general picture of the acidity trends within group 14. As expected, the acid strength increases down the group, although the acidity differences between germanium and tin derivatives are already rather small. As has been found before for amines, phosphines, and arsines, the carbon, silicon, germanium, and tin alpha,beta-unsaturated compounds are stronger acids( )than their saturated analogues. The acidifying effect of unsaturation is much larger for carbon than for Si-, Ge-, and Sn-containing compounds. The allyl anion is better stabilized by resonance than its Si, Ge, and Sn analogues, [CH(2)(-)(delta)--CH(+)(delta)(') --CH(2)(-)(delta)](-) vs [CH(2)(-)(delta)()II = CH(-)(delta)()III - XH(2)(-)(delta)()IV](-) (X = Si, Ge, Sn). The enhanced acid strength of unsaturated compounds is essentially due to a greater stabilization of the anion with respect to the neutral, because the electronegativity of the alpha,beta-unsaturated carbon group increases with its degree of unsaturation. The phenyl derivatives are systematically weaker acids than the corresponding ethynyl derivatives by 15-20 kJ mol(-)(1). Experimentally, toluene acidity is very close to that of propyne, because the deprotonation of propyne takes place preferentially at the =CH group rather than at the -CH(3) group.