Chronic enalapril treatment of dogs with naturally occurring, moderate to severe MR significantly delayed onset of CHF, compared with placebo, on the basis of number of CHF-free days, number of dogs free of CHF at days 500 and study end, and increased time to a combined secondary endpoint of CHF-all-cause death. Improvement in the primary endpoint, CHF-free survival, was not significant. Results suggest that enalapril modestly delays the onset of CHF in dogs with moderate to severe MR.

The reaction of HO 2 with CH 3 C(O)O 2 is examined using flash photolysis and FTIR smog chamber techniques. Time-resolved UV spectroscopy is used to follow the transient peroxy species. It yields reasonable concentration versus time profiles for CH 3 C(O)O 2 and HO 2 , but indicates anomalously high levels of secondary CH 3 O 2 radicals. Transient IR diode laser absorption confirms the HO 2 decay rates; however, the anticipated reaction model substantially underestimates the observed decay. The model is augmented by assuming that, in analogy with formaldehyde, there exists a reaction between HO 2 and acetaldehyde (the precursor for CH 3 C(O)O 2 ). Consistent with this, the fitted rate for the hypothesized reaction increases with increasing initial acetaldehyde level. Relative rate measurements reveal that chlorine atoms remove more CH 3 CHO relative to CH 3 OH in air as compared to nitrogen diluent. This supports the hypothesis since, in the presence of oxygen, HO 2 is formed and presents an additional acetaldehyde removal pathway. Employing the augmented model, analyses of HO 2 decay traces yield a CH 3 C(O)O 2 + HO 2 rate constant of k 1 ) (3.9 -2.3 +5.0) × 10 -13 e (1350(250)/T cm 3 s -1 . Reasons are discussed for why the present rate constants are 2-3 times larger than previously reported. FTIR-smog chamber studies reveal the reaction to proceed via two channels to (a) peracetic acid and O 2 and to (b) acetic acid and O 3 , with a branching fraction at 295 K that is less than half of the literature value. Time-resolved UV absorption measurements support this smaller fraction; averaged together the two methods give k 1b /k 1 ) 0.12 ( 0.04. As part of this work, relative rate techniques are used to measure k(Cl+CH 3 C-(O)OH) ) (2.5 ( 0.3) × 10 -14 cm 3 s -1 and k(Cl+CH 3 C(O)OOH) ) (4.5 ( 1.0) × 10 -15 cm 3 s -1 at 295 K.

And Clinical Relevance: Results suggest that administration of enalapril for up to 2 years did not have any demonstrable adverse effects on renal function in dogs with severe, compensated mitral regurgitation.

Few laboratory procedures describe the use of circular dichroism (CD) at the undergraduate level. To increase the number of laboratory exercises using CD, a thermal denaturation study of myoglobin using CD is described to assess protein stability. Values obtained from a more classic linear data analysis approach are consistent with data analyzed with a modern software program that "fits" the data set to a model using a non-linear approach. Both methods gave quantities consistent with reported literature values.

The techniques of time-resolved UV spectroscopy and transient IR absorption are used to examine the kinetics of the c-C5H9O2 + HO2 reaction over the temperature range 214−359 K. Deconvolution of the UV spectra yield time-dependent concentrations of both the cyclopentylperoxy and HO2 reactants; the transient IR experiments separately monitor HO2. Fits of these data to the appropriate reaction model yield a rate constant of k ro2+ho2 = (3. ) × 10-13e(1150±200)/ T cm3 s-1 for the title reaction. This result is compared to the single previous study of c-C5H9O2 + HO2 kinetics, and the implications for the atmospheric chemistry of peroxy radicals are discussed. As part of the present study, a relative rate of k cl+c5h10/k cl+ch3oh = (2.3 ± 0.3)e(300±200)/ T has been measured for the reaction Cl + c-C5H10 → c-C5H9 + HCl relative to Cl + CH3OH → CH2OH + HCl.