No abstract

Obesity is a major health problem in the USA, especially in minority populations over the age of 60 years, and the aging process can cause adverse effects on physical function. Previous research has shown that Tai Chi, resistance training (RT), and diet result in overall health improvements. However, the combination of these specific interventions has yet to be translated to obese older women in an urban setting. The purpose of this study was to examine a combined intervention on the primary outcomes of physical function and body composition. Using a nonrandomized design, 26 obese women (65.2 ± 8.1 years) completed a 12-week intervention; participants were assigned to an intervention (EXD) group or a control (CON) group. The EXD group (n = 17) participated in Tai Chi, RT, and a dietary session. The CON group (n = 9) was asked to continue their normal lifestyle. Timed up and go (TUG) time was reduced by 0.64 ± 2.1 seconds (P = 0.04) in the EXD group while the CON group saw a borderline significant increase of 0.71 sec (P = 0.051). The combined intervention helped improve performance on TUG time, but there were no significant increases in other body composition or function measures.

Background The Dietary Approaches to Stop Hypertension (DASH) diet is widely recommended to lower blood pressure, but its mechanisms of action are unclear. Lines of evidence suggest an interaction with the renin-angiotensin-aldosterone system (RAAS). Objective We conducted a randomized, controlled, cross-over feeding trial to test RAAS-related mechanisms underlying the DASH diet in patients with isolated systolic hypertension. Methods Participants entered a 1-wk run-in period on a control (CON) diet and then consumed the DASH or CON diets for 4 wk each in randomized sequence. Calorie content was controlled to maintain weight, and sodium intake was set at 3 g daily. After each diet, participants had hormonal and hemodynamic assessments obtained at baseline, in response to RAAS inhibition with captopril (CAP) 25 mg, and to graded angiotensin II (AngII) infusions (1 ng/kg and 3 ng/kg × 45 min). Primary outcomes were mean arterial pressure (MAP) and renal blood flow (RBF), and secondary outcomes were diastolic function, pulse wave velocity (PWV), plasma renin activity (PRA), and aldosterone (ALDO) responses by diet. Results In total, 44 (19 female) participants completed the study. DASH + CAP significantly lowered MAP compared with CON + CAP (83 ± 11 mmHg compared with 88 ± 14 mmHg, P <0.01). RBF was increased with DASH + CAP compared with CON + CAP (486 ± 149 cc/min compared with 451 ± 171 cc/min, P <0.001). Study diet did not change PWV but CAP reduced diastolic function on the DASH diet (P <0.05). DASH + CAP significantly increased PRA compared with CON + CAP (1.52 ± 1.78 ng/mL/min compared with 0.89 ± 1.17 ng/mL/min; P <0.001). ALDO sensitivity to AngII infusion was greater with DASH when compared to CON (17.4 ± 7.7 ng/mL compared with 13.8 ± 6.2 ng/dL, P <0.05) as was DASH + CAP compared with CON + CAP (15.1 ± 5.3 ng/dL compared with 13.1 ± 5.9 ng/mL, P <0.05). Conclusions The DASH diet interacts with the RAAS resulting in vascular and hormonal responses similar to a natriuretic effect, which appears to augment the hypotensive effect of angiotensin-converting enzyme (ACE) inhibition in individuals with isolated systolic hypertension. This trial was registered at clinicaltrials.gov as NCT00123006.

Inconsistencies have been reported on the effect of sex on aldosterone levels leading to clinical confusion. The reasons for these inconsistencies, are uncertain but include: estrogen and/or its receptor modulating target gene responses to mineralocorticoid receptor activation and aldosterone secretagogues’ levels. This study’s goal was to determine whether aldosterone’s biosynthesis also differed by sex. Two approaches were used. First, plasma renin activity (PRA) and aldosterone were measured in rats. Both were significantly higher in males. Secondly, using rat zona glomerulosa (ZG) cells, we assessed three ex-vivo areas:1) activity/levels of early steps in aldosterone’s biosynthesis (StAR and CYP11A1); 2) activity/levels of a late step (CYP11B2); and 3) the status of the MR mediated, ultrashort-feedback-loop. Females had higher expression of CYP11A1 and StAR; and increased CYP11A1 activity (increased pregnenolone/ corticosterone levels) but did not differ in CYP11B2 expression or activity (aldosterone/ levels). Activating the ZG’s MR (thereby activating the ultrashort-feedback-loop) reduced CYP11B2’s activity similarly in both sexes. Ex-vivo, these molecular effects were accompanied, in females, by lower aldosterone basally but higher aldosterone with angiotensin II stimulation. In conclusion, we documented that not only was there a sex-mediated difference in the activity of aldosterone’s biosynthesis, but also these differences at the molecular level, help explain the variable reports on aldosterone’s circulating levels. Basally, both in-vivo and ex-vivo, males had higher aldosterone levels, likely secondary to higher aldosterone secretagogue levels. However, in response to acute stimulation, aldosterone levels are higher in females because of the greater levels and/or activity of their StAR/CYP11A1.