Left ventricular growth response to exercise and cigarette smoking: data from LARGE Heart.

BACKGROUND: Increasing left ventricular mass is a risk factor for cardiovascular morbidity and mortality. OBJECTIVE: To examine the possible association of smoking with the left ventricular growth response in men. METHODS: Left ventricular mass was measured in 309 army recruits before and after an identical 12-week physical training programme. Left ventricular mass was determined using cardiovascular magnetic resonance. RESULTS: Left ventricular mass increased with training (mean (standard deviation (SD)) 3.83 (10.81) g, p<0.001). By univariate analysis, exercise-induced change in left ventricular mass was positively associated with cigarette smoking (mean (SD) 1.69 (11.10) g v 4.76 (10.23) g for non-smokers v ex- and current smokers, respectively; p = 0.026), whereas age, height, diastolic and systolic blood pressure (SBP), alcohol consumption or indices of physical activity were not significantly associated with change in left ventricular mass. Multivariate analysis showed body weight, smoking status and SBP to be independent predictors of left ventricular mass (incremental R(2) = 3.4%, p = 0.004; R(2) = 4.9%, p = 0.024; and R(2) = 1.7%, p = 0.041, respectively). CONCLUSIONS: Cigarette smoking and SBP are associated with exercise-induced left ventricular growth in young men. The positive association of smoking with changes in left ventricular mass is surprising, given the limited exposure of these subjects to smoking, and although these data do not prove causation, they are of great interest to those trying to uncover the drivers of left ventricular hypertrophy, as well as to those examining the possible ill-effects of smoking in the young.

Post-insemination milk progesterone concentration and embryo survival in dairy cows.

Logistic regression analysis was used to evaluate the relationship between post-insemination milk progesterone concentration and embryo survival, and between milk yield and milk progesterone concentration. Milk samples were collected on Days 1, 4, 5, 6, and 7 (insemination=Day 0) following 871 inseminations in spring-calving dairy cows. Milk progesterone concentrations were measured by enzyme-immunoassay and pregnancy diagnosis was conducted with transrectal ultrasonography at approximately Day 30. There was a negative linear relationship (P<0.01) between milk progesterone concentration on Day 4 and embryo survival while, in contrast, there was a positive linear and quadratic relationship between milk progesterone concentration on Days 5, 6 and 7 (P<0.05) and also between the rate of change in progesterone concentrations between Days 4 and 7 inclusive and embryo survival (P<0.05). There was a weak negative linear relationship between average daily milk yield at the time of insemination and milk progesterone concentrations (P<0.001). There was no association between many production parameters, including liveweight and body condition score measured at various stages between calving and insemination, and milk progesterone concentration between Days 4 and 7 inclusive (P>0.05). In conclusion, low progesterone during Days 5-7 (after insemination) was associated with low fertility in dairy cows and there were indications of a range of progesterone concentrations within which embryo survival was maximal.