Mohammed Alkatan

Impact of blood pressure perturbations on arterial stiffness

Although the associations between chronic levels of arterial stiffness and blood pressure (BP) have been fairly well studied, it is not clear whether and how much arterial stiffness is influenced by acute perturbations in BP. The primary aim of this study was to determine magnitudes of BP dependence of various measures of arterial stiffness during acute BP perturbation maneuvers. Fifty apparently healthy subjects, including 25 young (20-40 yr) and 25 older adults (60-80 yr), were studied. A variety of BP perturbations, including head-up tilt, head-down tilt, mental stress, isometric handgrip exercise, and cold pressor test, were used to encompass BP changes induced by physical, mental, and/or mechanical stimuli. When each index of arterial stiffness was plotted with mean BP, all arterial stiffness indices, including cardio-ankle vascular index or CAVI (r = 0.50), carotid-femoral pulse wave velocity or cfPWV (r = 0.51), brachial-ankle pulse wave velocity or baPWV (r = 0.61), arterial compliance (r = -0.42), elastic modulus (r = 0.52), arterial distensibility (r = -0.32), β-stiffness index (r = 0.19), and Youngs modulus (r = 0.35) were related to mean BP (all P < 0.01). Changes in CAVI, cfPWV, baPWV, and elastic modulus were significantly associated with changes in mean BP in the pooled conditions, while changes in arterial compliance, arterial distensibility, β-stiffness index, and Youngs modulus were not. In conclusion, this study demonstrated that BP changes in response to various forms of pressor stimuli were associated with the corresponding changes in arterial stiffness indices and that the strengths of associations with BP varied widely depending on what arterial stiffness indices were examined.

Hypotensive effects of solitary addition of conventional nonfat dairy products to the routine diet: a randomized controlled trial

BACKGROUND The high consumption of low-fat and nonfat dairy products is associated with reduced risk of high blood pressure. OBJECTIVE We aimed to investigate whether the solitary addition of nonfat dairy products to the normal routine diet was capable of lowering blood pressure in middle-aged and older adults with elevated blood pressure. DESIGN With the use of a randomized, crossover intervention-study design, 49 adults (56% women) with elevated blood pressure (mean ± SEM age: 53 ± 2 y; systolic blood pressure: 135 ± 1; diastolic blood pressure: 80 ± 1 mm Hg) underwent a high-dairy condition (+4 servings conventional nonfat dairy products/d) and isocaloric no-dairy condition (+4 servings fruit products/d) in which all dairy products were removed. Both dietary conditions lasted 4 wk with a 2-wk washout before crossing over into the alternate condition. RESULTS The high-dairy condition produced reductions in systolic blood pressure (135 ± 1 to 127 ± 1 mm Hg) and pulse pressure (54 ± 1 to 48 ± 1 mm Hg) (both P < 0.05). The hypotensive effects were observed within 3 wk after the initiation of the dietary intervention and in both casual seated and ambulatory (24-h) measurements (P < 0.05). Pulse pressure was increased after the removal of all dairy products in the no-dairy condition (54 ± 1 to 56 ± 1 mm Hg; P < 0.05). There were no changes in diastolic blood pressure after either dietary condition. CONCLUSION We concluded that the solitary manipulation of conventional dairy products in the normal routine diet would modulate blood pressure in middle-aged and older adults with prehypertension and hypertension. This trial was registered at clinicaltrials.gov as NCT01577030.

Effects of Swimming and Cycling Exercise Intervention on Vascular Function in Patients With Osteoarthritis.

Swimming exercise is an ideal and excellent form of exercise for patients with osteoarthritis (OA). However, there is no scientific evidence that regular swimming reduces vascular dysfunction and inflammation and elicits similar benefits compared with land-based exercises such as cycling in terms of reducing vascular dysfunction and inflammation in patients with OA. Forty-eight middle-aged and older patients with OA were randomly assigned to swimming or cycling training groups. Cycling training was included as a non-weight-bearing land-based comparison group. After 12 weeks of supervised exercise training, central arterial stiffness, as determined by carotid-femoral pulse wave velocity, and carotid artery stiffness, through simultaneous ultrasound and applanation tonometry, decreased significantly after both swimming and cycling training. Vascular endothelial function, as determined by brachial flow-mediated dilation, increased significantly after swimming but not after cycling training. Both swimming and cycling interventions reduced interleukin-6 levels, whereas no changes were observed in other inflammatory markers. In conclusion, these results indicate that regular swimming exercise can exert similar or even superior effects on vascular function and inflammatory markers compared with land-based cycling exercise in patients with OA who often has an increased risk of developing cardiovascular disease.

Improved Function and Reduced Pain after Swimming and Cycling Training in Patients with Osteoarthritis

Objective. Arthritis and its associated joint pain act as significant barriers for adults attempting to perform land-based physical activity. Swimming can be an ideal form of exercise for patients with arthritis. Yet there is no information on the efficacy of regular swimming exercise involving patients with arthritis. The effect of a swimming exercise intervention on joint pain, stiffness, and physical function was evaluated in patients with osteoarthritis (OA). Methods. Using a randomized study design, 48 sedentary middle-aged and older adults with OA underwent 3 months of either swimming or cycling exercise training. Supervised exercise training was performed for 45 min/day, 3 days/week at 60–70% heart rate reserve for 12 weeks. The Western Ontario and McMaster Universities Arthritis Index was used to measure joint pain, stiffness, and physical limitation. Results. After the exercise interventions, there were significant reductions in joint pain, stiffness, and physical limitation accompanied by increases in quality of life in both groups (all p < 0.05). Functional capacity as assessed by maximal handgrip strength, isokinetic knee extension and flexion power (15–30% increases), and the distance covered in the 6-min walk test increased (all p < 0.05) in both exercise groups. No differences were observed in the magnitude of improvements between swimming and cycling training. Conclusion. Regular swimming exercise reduced joint pain and stiffness associated with OA and improved muscle strength and functional capacity in middle-aged and older adults with OA. Additionally, the benefits of swimming exercise were similar to the more frequently prescribed land-based cycling training. Trial registration: clinicaltrials.gov NCT01836380.

Effects of non-fat dairy products added to the routine diet on vascular function: A randomized controlled crossover trial

BACKGROUND AND AIMS High consumption of low- and non-fat dairy products is associated with reduced risk of high blood pressure (BP) and central arterial stiffness. However, interventional studies to determine if the addition of non-fat dairy products to the diet is capable of reducing central BP and improving vascular function are lacking. The aim of this study was to determine if the solitary addition of non-fat dairy products to the normal routine diet would reduce central BP and improve vascular function in middle-aged and older adults with elevated BP. METHODS AND RESULTS Using a randomized, crossover intervention study design, forty-nine adults (44% men, 53 ± 2 years, 170 ± 2 cm, 88 ± 3 kg; mean ± SEM) with elevated BP (134 ± 1/81 ± 1 mm Hg) underwent a High Dairy condition (+4 servings/day of conventional non-fat dairy products) and No Dairy condition (+4 servings/day fruit products) in which all dairy products were removed. Both dietary conditions lasted 4 weeks with a 2-week washout before crossing over into the alternate condition. The High Dairy condition produced reductions in central systolic BP (-3 ± 1 mm Hg) and carotid-femoral pulse wave velocity (-0.5 ± 0.1 m/sec), with a concomitant increase in brachial flow-mediated dilation (+1.1 ± 0.4%) and cardiovagal baroreflex sensitivity (+5 ± 1 ms/mm Hg) (P < 0.05 for all vs. baseline). In the No Dairy condition, brachial flow-mediated dilation was reduced (-1.0 ± 0.1%, P < 0.05 vs. baseline). CONCLUSIONS The solitary manipulation of conventional dairy products in the normal routine diet modulates levels of central BP and vascular function in middle-aged and older adults with elevated BP. CLINICAL TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01577030.

Interrelationships Among Various Measures of Central Artery Stiffness

BACKGROUND A number of different techniques and methodologies have been applied to quantify stiffness of arteries. Because measures of arterial stiffness differ in regards to measurement locations as well as properties, it is not clear how well these measures that are supposed to reflect the same arterial wall properties are related. METHODS Interrelationships between different measures of arterial stiffness were evaluated in 50 apparently healthy subjects varying in age. RESULTS Significant relations ranging from mild to strong were observed among measures of arterial stiffness while some measures were not significantly associated. Cardio-ankle vascular index (CAVI) was significantly associated with carotid-femoral pulse wave velocity (cfPWV) and brachial-ankle pulse wave velocity (baPWV). Ultrasound-derived measures of arterial stiffness (e.g., compliance, distensibility) were weakly or not significantly related to pulse wave velocity (PWV) measures. The limits of agreement between each of arterial stiffness measures based on the Bland-Altman analyses indicate that there were close agreements (CI = 1.12-1.52) between CAVI, cfPWV, and baPWV. However, agreements between PWV measures and ultrasound-derived measures were mild to moderate. β-stiffness index demonstrated large 95% CIs with other measures. When associations between relative changes in various measures of arterial stiffness in response to isometric handgrip exercise were evaluated, the general trend of associations was similar to the relations observed at rest. β-stiffness index was not related to most measures of arterial stiffness. CONCLUSION These results suggest that the techniques used to assess arterial stiffness may not be interchangeable in clinical and research settings and that comparisons of findings obtained with different arterial stiffness measures should be conducted with caution.

Serum brain-derived neurotrophic factor mediates the relationship between abdominal adiposity and executive function in middle age

OBJECTIVES Excessive adipose tissue, especially in the abdominal area, is associated with increased risk of dementia in older adults. However, the mechanisms underlying this relationship are poorly understood. As increased adiposity is also associated with lower circulating levels of brain-derived neurotrophic factor (BDNF), a key molecule modulating brain plasticity and neuronal regeneration, we hypothesized that the changes in cognition that occur as a result of excessive abdominal adiposity would be driven by lower levels of circulating BDNF. METHODS Fasting blood samples were obtained from 60 participants aged 40-60 years (mean±SD=52.3±5.6) and BDNF levels were assessed with an enzyme linked immunosorbent assay. Abdominal adiposity was measured using a ratio of waist circumference to hip circumference (WHR). Participants also completed a neuropsychological assessment battery to assess executive function. Statistical mediation was assessed using traditional causal steps and nonparametric bootstrapping. RESULTS Higher WHR was significantly associated with poorer performance on the Controlled Oral Word Association (COWA) letter fluency test (β=-0.489; p=.003) and lower levels of circulating BDNF (β=-0.345; p=.006). Linear regression and bootstrapping methods indicated that BDNF fully mediated the relationship between WHR and performance on the COWA (β=0.60; 95% confidence interval [-3.79, -0.26]). CONCLUSIONS The relationship between higher WHR and verbal fluency was fully statistically mediated by circulating BDNF levels. The BDNF pathway is thus a useful probable mechanism through which executive function decline occurs in individuals with high abdominal adiposity. BDNF enhancing interventions (physical exercise and dietary restriction) could thus be used to improve executive function in these individuals.

Impact of Hot Yoga on Arterial Stiffness and Quality of Life in Normal and Overweight/Obese Adults.

BACKGROUND Obesity is associated with arterial stiffening and diminished quality of life. Bikram yoga may be a feasible alternative to traditional exercise among obese individuals. Accordingly, the purpose of this study was to investigate the impact of Bikram yoga, a heated style of hatha yoga, on arterial stiffness in normal and overweight/obese adults. METHODS Forty-three (23 normal body mass index or BMI; 20 overweight/obese) apparently healthy participants completed an 8-week Bikram yoga intervention. Body composition was estimated via dual energy x-ray absorptiometry, arterial stiffness was measured via brachialankle pulse wave velocity, and health-related quality of life was assessed via RAND 36-Item Short Form survey at baseline and at the end of the 8-week intervention. RESULTS After the intervention, brachial-ankle pulse wave velocity decreased (P < .05) in overweight/obese participants while no such changes were observed in normal BMI participants. In the quality of life measures, emotional well-being improved (P < .05) in both groups, and general health improved (P < .05) only in the normal weight BMI group. CONCLUSION Bikram yoga ameliorates arterial stiffness in overweight/obese adults and can positively impact quality of life regardless of BMI.

Midlife Arterial Stiffness and Brain Activation During Working Memory Task

Objective: Arterial stiffness is associated with cognitive decline and may serve as an early marker of brain vul- nerability. In search of potential early intervention targets, the present study examined the neural correlates of working memory in relation to arterial stiffness in middle-aged, cognitively healthy adults. Methods: Twenty-eight adults, ages 40- 60 years, completed a 2-Back verbal working memory task during fMRI. Arterial stiffness was measured using the � - stiffness index via simultaneous ultrasound and applanation tonometry on the carotid artery. Mean task-related activation intensity was determined for 12 a priori regions of interest (ROI). Statistical analyses included partial correlations, con- trolling for hypertension status and antihypertensive medication. Results: Arterial stiffness was correlated negatively with task-related activation in 3 ROIs: left precentral gyrus/BA 6 (r=-0.64, p<0.001), left precentral/middle frontal gyrus (r=-0.62, p=0.001) and left superior parietal lobule/BA 7 (r=-0.48, p=0.013). There was also a negative association be- tween arterial stiffness and task-related activation in the right superior frontal gyrus/BA 6 (r=-0.45, p=0.023). Conclu- sions: Greater arterial stiffness was significantly associated with decreased task-related brain activation during a verbal working memory task, possibly reflecting increased vulnerability for cognitive impairment. Arterial stiffness should be investigated further as an early marker of cognitive risk and a potential target for early intervention.