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Biomedical subjects

Roberta K Oka

Publications and source records attributed to Roberta K Oka.

16 recordsLinked to original sources
PubMed2005

Effect of treadmill testing and exercise training on self-efficacy in patients with heart failure.

BACKGROUND: Self-efficacy is a person's confidence in being able to successfully perform a specific activity or behavior. Self-efficacy has been shown to influence exercise capacity in patients post myocardial infarction, but has not been fully explored in patients with heart failure (HF). This study examined the impact of performance of a single treadmill exercise test and participation in a 3-month program of walking and resistance exercise on self-efficacy in HF patients. METHODS: 24 patients were randomized to either a home-based walking and resistance exercise program or usual care for 3 months. Prior to enrollment into the exercise program all participants performed a single treadmill exercise test with respiratory gas analysis. Self-efficacy questionnaires were completed at 3 time points, 1) prior to performance of an exercise treadmill test; 2) immediately after completing an exercise test; and 3) at the end of a 3-month exercise program. RESULTS: Self-efficacy for walking (p=0.07), climbing (p=0.17), lifting (p=0.73) and general activity (p=0.15) did not improve after performance of a single treadmill exercise test and usual care. However, self-efficacy for walking increased after 3 months of a walking and resistance exercise program. (p=0.04). CONCLUSIONS: The findings from this study suggest that in patients with stable mild to moderate heart failure, self-efficacy is improved with participation in a home-based walking and endurance exercise program. Self-efficacy is not enhanced by performance of a single treadmill exercise test and usual care.

Adult↗
PubMed2005

The impact of type 2 diabetes and peripheral arterial disease on quality of life.

Peripheral arterial disease (PAD) is associated with impaired walking distance as the result of claudication and reduced quality of life (QOL). Diabetes mellitus (DM) is commonly associated with PAD. The combined effect of DM and PAD versus PAD alone on walking distance and QOL is not well understood. This prospective, descriptive study examined walking distance and QOL associated with DM and PAD compared with PAD alone. Walking distance was assessed by an exercise treadmill test to determine initial claudication distance and absolute claudication distance and by self-report using the Walking Impairment Questionnaire. QOL was measured using the Short Form-36. The overall sample consisted of 92 men and women with PAD and DM or PAD alone. Of the total sample, 74 participants had PAD with ABI less than 0.9 mm Hg and 18 subjects had PAD and uncontrolled DM with hemoglobin A1c 7.0 mg/dL or greater. The mean age was 72 years (standard deviation [SD] = 7) for the PAD only group and 75 years (SD = 8) (not significant) for the PAD and DM groups. Initial claudication distance was greater in subjects with PAD only (186.9 m, SD = 136.4) than in diabetic subjects with PAD (127.3 m, SD = 70.0, P = .01). Absolute claudication distance was higher in patients with PAD only (461.3 m, SD 308) than in diabetic subjects with PAD (279.1 m, SD = 100, P = .01). Self-reported walking speed was reduced in patients with DM and PAD compared with patients with PAD only (P = .05). Diabetic patients with PAD reported impaired role function (P = .007), general health (P = .03), and social function (P = .04) compared with patients with PAD only. We conclude that DM has a significant detrimental impact on walking distance and QOL in patients with PAD. These findings suggest that diabetic patients with PAD are at greater risk for experiencing social isolation, impaired role function, reduced overall perceptions of general health, and impaired functional capacity. Future studies with larger sample sizes are needed to identify factors that contribute to these perceptions in diabetic patients with PAD.

Aged↗
PubMed2005

Abnormal cardiovascular response to exercise in patients with peripheral arterial disease: Implications for management.

Exercise is beneficial in improving claudication and functional capacity in patients with peripheral arterial disease (PAD). However, the physiologic response during and after exercise testing in this patient population has not been fully described. This study examined the cardiovascular response to exercise and explored the potential contribution of vascular noncompliance to exercise-induced hypertension in 124 patients with PAD and claudication and 31 comparison (C) patients with PAD with no walking limitations. Maximal walking distance was determined by an exercise treadmill test. Heart rate and blood pressure were monitored before, during, and immediately after an exercise test. Vascular compliance of the small and large vessels was measured using pulse waveform analysis. Individuals with low supine resting heart rate had longer pain-free walking distance (r = -0.195, P = .019) and maximal walking versus the C group (62 beats/min, standard deviation [SD] = 10, P = .02). Systolic blood pressure during supine rest was significantly lower for the PAD group (mean = 141 mm Hg, +/- SD = 22) versus the C group (mean = 153 mm Hg, +/- SD = 20, P = .003). Vascular compliance of large vessels was higher in the C group (mean = 4.13 +/- 4.13 mL/mm Hg x 100) compared with the PAD group (mean = 2.95 +/- 1.6 mL/mm Hg x 100). This study describes the exaggerated exercise cardiovascular response and impaired vascular compliance in patients with PAD. These results provide further evidence supporting the importance of a monitored treadmill exercise test before initiation of an exercise program to ensure safe and accurate exercise recommendations, and to identify individuals that require more intensive pharmacotherapy to prevent exercise-induced hypertension and tachycardia.

Aged↗
PubMed2005

Statin therapy in heart failure.

PURPOSE OF REVIEW: The 3-hydroxy-3-methylglutaryl-coenzyme-A reductase inhibitors, or statins, have been shown to reduce cardiovascular morbidity and mortality among a wide spectrum of patients with established atherosclerotic vascular disease. Mounting experimental and clinical evidence also suggest a potential benefit as well as theoretical harm of statin therapy in patients with heart failure. RECENT FINDINGS: This article briefly summarizes the therapeutic properties of statins that may be of benefit to patients with heart failure and the theoretical adverse effects of cholesterol reduction in this group of patients. A number of nonrandomized clinical studies over the past several years have shown an association between statin use and reduced overall mortality. Several large-scale randomized studies designed to confirm these findings are currently under way. SUMMARY: Statin therapy appears to improve clinical outcomes in patients with both ischemic and nonischemic cardiomyopathy independently of their cholesterol-lowering properties. The theoretical adverse properties of statins in heart failure patients have not been substantiated in small to medium-sized clinical trials. Although the encouraging results of these preliminary studies suggest a role for statin therapy in heart failure, larger studies are needed to validate these findings. Several ongoing randomized trials are currently under way to evaluate the effect of statin therapy on cardiovascular outcomes in heart failure patients. The results of these studies, expected in the next several years, should provide scientific evidence for the role of statins in the treatment of failure.

Cardiac Output, Low↗
PubMed2005

The impact of exercise on body composition and nutritional intake in patients with heart failure.

Little is known about the nutritional status of heart failure patients and the potential synergistic effects between nutritional intake and exercise. This small, randomized trial examined the effects of a 3-month exercise program on body composition and nutritional intake in 31 men (17 exercisers; 14 controls), aged 30-76 years (mean, 56 years) with stable class II-III heart failure. Baseline and 3-month evaluations included body mass index, body fat mass by triceps skinfold thickness, dietary intake by food frequency questionnaire, and the 6-minute walk test. Exercise consisted of walking 3 d/wk and resistance exercises 2 d/wk for 40-60 minutes. Dietary recommendations were consistent with the American Heart Association/American College of Cardiology heart failure guidelines. Exercisers decreased body weight (p=0.001), body mass index (p=0.0001), and triceps skinfold thickness (p=0.03) and improved 6-minute walk test (p=0.01) compared with controls. Exercisers also demonstrated trends toward decreased total caloric and cholesterol intake and a three-fold higher carbohydrate, fiber, and beta carotene intake vs. controls. In this study population, protein, fiber, and magnesium intake were below recommended daily allowance. After exercise, body mass index was reduced, accompanied by dietary modifications including greater intake of foods with higher moisture content. Further study is needed to investigate the interaction among diet, exercise, and weight.

Adult↗
PubMed2005

Suboptimal intensity of risk factor modification in PAD.

This study extends earlier trials indicating that atherosclerosis risk factors are underdetected and undertreated in peripheral arterial disease (PAD) patients. Recognition and treatment of hyperlipidemia and hypertension in PAD patients is suboptimal. Diabetes appears to be detected more frequently although glycemic control is still suboptimal. The use of antiplatelet therapy is particularly underutilized. Additionally, despite the demonstrated efficacy of regular exercise in PAD patients, almost half of the study sample was sedentary. Approximately one third of the current study sample was overweight and nearly one third was obese by ATP-III guidelines. Only 31% of subjects were taking dietary measures to improve their cardiovascular health, and even fewer were physically active. To rectify suboptimal management of risk factors, there is a need for increased public awareness of PAD, reimbursement and implementation of screening programs and more aggressive treatment. Future studies are needed to examine innovative interventions for identification and management of cardiovascular risk factors in patients with PAD.

Age Distribution↗
PubMed2005

Vascular compliance versus flow-mediated vasodilation: correlation with cardiovascular risk factors.

Cardiovascular risk factors are associated with impaired endothelium dependent vasodilation and reduced vascular compliance. In this study, the correlation with cardiovascular risk factor score of two common techniques for assessing vascular function was compared. Risk factors and vascular function were evaluated in a study population of 122 people with peripheral arterial disease (PAD) or with risk factors for PAD (73 men and 49 women; mean age 69 years). A risk factor score was determined using Framingham criteria. Vascular compliance was assessed by pulse waveform analysis and simultaneous blood pressure measurement. Flow-mediated vasodilation of the brachial artery was measured using duplex ultrasonography. Participants with a high risk factor score had significantly reduced vascular compliance of large and small vessels. By contrast, the difference in flow-mediated vasodilation between those with a high or low risk factor score did not reach statistical significance. There was a significant negative correlation between vascular compliance and risk factor score. There was a similar trend between flow-mediated vasodilation and risk factor score, but this did not reach statistical significance. A measure of vascular compliance was more significantly correlated with cardiovascular risk factor score than was a measure of flow-mediated vasodilation in the study population. Neither technique provided values that were highly correlated with risk factor burden. Although flow-mediated vasodilation is a preferred research tool for assessing vascular function, technical limitations and biological variability may reduce its clinical application in assessing individual cardiovascular risk.

Aged↗
PubMed2005

A pilot study of L-arginine supplementation on functional capacity in peripheral arterial disease.

Peripheral arterial disease (PAD) impairs walking capacity and is often associated with a profound endothelial vasodilator dysfunction, characterized by reduced bioactivity and/or synthesis of endothelium-derived nitric oxide (NO). Previous studies have suggested that dietary supplementation of L-arginine, the precursor of NO, improves endothelium-dependent vasodilation, limb blood flow and walking distance. However, these studies have been small, and have used large intravenous doses of L-arginine. The optimal dose of L-arginine has not been determined. Accordingly, this pilot study was conducted to establish the lowest effective oral dose of L-arginine to improve walking distance in preparation for the definitive study. Patients with PAD and intermittent claudication (n = 80) participated in this study. Eligibility criteria included: (1) ankle-brachial index (ABI) at rest < or = 0.90; (2) post-exercise reduction in ABI > or = 25%; and (3) difference in absolute claudication distance of < or = 25% between two consecutive treadmill tests. Treadmill testing was performed using the Skinner-Gardner protocol and community-based walking was assessed using the walking impairment questionnaire. Patients were randomly assigned to oral doses of 0, 3, 6 or 9 g of L-arginine daily in three divided doses for 12 weeks. Treadmill testing was performed prior to administration of the study drug and again after 12 weeks of treatment. The study drug was well tolerated, with no significant adverse effects of L-arginine therapy. The safety laboratory studies were unremarkable, except for a statistically significant reduction in hematocrit in the L-arginine-treated groups. There was no significant difference observed in absolute claudication distance between the groups. However, a trend was observed for a greater increase in walking distance in the group treated with 3 g L-arginine daily, and there was a trend for an improvement in walking speed in patients treated with L-arginine. This pilot study provided data for safety, for power calculation and for dosing for the larger definitive trial that is now underway.

Administration, Oral↗
PubMed2004

Exercise patterns and cardiovascular fitness of patients with peripheral arterial disease.

Peripheral arterial disease (PAD) is characterized by walking impairment as the result of claudication, which is improved by exercise. Few studies have examined the impact of existing exercise patterns in community-dwelling patients with PAD on cardiovascular fitness and absolute claudication distance (ACD). This descriptive study examines exercise patterns, walking distance, and cardiovascular fitness in a sample of community-dwelling older adults with PAD. Approximately 50% of subjects reported walking 4 (+/-2) days per week for 38 +/- 24 minutes. ACD (exercisers = 459.9 +/- 272; non-exercisers = 351.2 +/- 266.3, P = .06) and initial claudication distance (exercisers = 198.5 +/- 139.7; non-exercisers = 138.7 +/- 95.8 P = .02) were similar between groups. The workload accomplished was approximately 4.1-4.7 metabolic equivalents. Resting heart rate (HR) was associated with initial claudication distance ( r = -.37, P = .001) and ACD ( r = -.46, P < .01) and was lower in the group of exercisers versus the non-exercisers ( P = .05). Mean resting SBP was elevated and continued to increase at peak exercise with no difference between groups ( P = .75). Quality of life was poor for both groups. Simultaneous multiple regression analysis was performed to determine predictors of peak exercise HR. The model included gender, age, current exercise, ankle-brachial index, coronary artery disease, beta blockers, ACD, and atrial fibrillation (R = 44%, P = .01). Higher peak exercise HR was associated with older age, female gender, no beta blockers, and greater ACD ( P < .01). The findings from this descriptive study demonstrate the need for larger long-term studies to address issues of exercise adherence and the psychologic and functional benefits of exercise.

Activities of Daily Living↗
PubMed2004

Age, body mass index, and serum prostate-specific antigen correlate with bone loss in men with prostate cancer not receiving androgen deprivation therapy.

OBJECTIVES: Preexisting osteopenia and osteoporosis in men with prostate cancer are of concern due to accelerated bone loss during androgen deprivation therapy (ADT). We sought to identify risk factors for osteoporosis in men with prostate cancer who have not received ADT to help determine which patients may need bone mineral density (BMD) testing prior to ADT. METHODS: Lumbar spine and hip BMD testing were performed using dual-energy x-ray absorptiometry in 34 men with nonmetastatic prostate cancer who were not receiving ADT. The demographic, health status, lifestyle, and disease variables (Gleason score, clinical stage, and prostate-specific antigen level) were obtained and analyzed using univariate and multivariate methods for their role in spine and hip BMD levels. RESULTS: Of the 34 men, 73.5% had osteopenia (55.9%) or osteoporosis (17.6%) of the spine and/or hip. On univariate analysis, aging, lower body mass index, and elevated prostate-specific antigen level correlated significantly with bone loss in the spine and hip. Regression models showed age independently predicted bone loss in the spine (R2 = 0.14). Prostate-specific antigen was an independent predictor of low BMD in the trochanter (R2 = 0.18), and body mass index independently predicted low BMD in the femoral neck (R2 = 0.19). Compared with men younger than 70 years old, men 70 years old or older had less BMD in the spine (P = 0.017), femoral neck (P = 0.047), and trochanter (P = 0.030). CONCLUSIONS: A high prevalence of osteopenia or osteoporosis was found in men with prostate cancer not receiving ADT. Consideration should be given to performing BMD studies in men older than 70 years and with slender stature before initiating ADT.

Absorptiometry, Photon↗
PubMed2004

Predictors of physical function in patients with peripherial arterial disease and claudication.

Limitation of walking due to claudication is the hallmark of peripheral arterial disease. The purpose of this secondary analysis was to identify biobehavioral predictors of physical function in peripheral arterial disease patients that included walking ability, gender, age, disease severity, environmental factors (social support), and medical comorbidity (arthritis). All subjects performed an exercise treadmill test to determine initial and absolute claudication distance. The sample consisted of 97 peripheral arterial disease patients, 71 (73%) men and 26 (27%) women, with a mean age of 73+/-8 years (range 52-90 years). Initial claudication distance occurred at 171.88+/-136.35 m. Absolute claudication distance was 421.03+/-286.37 m. A simultaneous multiple regression analysis was performed to determine predictors of physical function. The model accounted for 35% of the variance (p<0.001) and included personal characteristics (age, gender, years of education), severity of disease by ankle-brachial index, environmental factors of social support (marital status), absolute claudication distance, and arthritis. Education (p=0.011), absolute claudication distance (p=0.014), social support (p=0.026), arthritis (p=0.028), and age (p=0.033) were the strongest predictors of physical function. This study identifies biobehavioral factors that place peripheral arterial disease patients at greater risk for reduced physical function and provides a rationale for interventions that improve walking ability.

Activities of Daily Living↗
PubMed2003

Endothelial dysfunction induced by hyperhomocyst(e)inemia: role of asymmetric dimethylarginine.

BACKGROUND: Endothelial function is impaired by hyperhomocyst(e)inemia. We have previously shown that homocyst(e)ine (Hcy) inhibits NO production by cultured endothelial cells by causing the accumulation of asymmetric dimethylarginine (ADMA). The present study was designed to determine if the same mechanism is operative in humans. METHODS AND RESULTS: We studied 9 patients with documented peripheral arterial disease (6 men; 3 women; age, 64+/-3 years), 9 age-matched individuals at risk for atherosclerosis (older adults; 9 men; age, 65+/-1 years), and 5 young control subjects (younger adults; 5 men; age, 31+/-1 years) without evidence of or risk factors for atherosclerosis. Endothelial function was measured by flow-mediated vasodilatation of the brachial artery before and 4 hours after a methionine-loading test (100 mg/kg body weight, administered orally). In addition, blood was drawn at both time points for measurements of Hcy and ADMA concentrations. Plasma Hcy increased after the methionine-loading test in each group (all, P<0.001). Plasma ADMA levels rose in all subjects, from 0.9+/-0.2 to 1.6+/-0.2 micromol/L in younger adults, from 1.5+/-0.2 to 3.0+/-0.4 micromol/L in older adults, and from 1.8+/-0.1 to 3.9+/-0.3 micromol/L in peripheral arterial disease patients (all, P<0.001). Flow-mediated vasodilatation was reduced from 13+/-2% to 10+/-1% in younger adults, from 6+/-1% to 5+/-1% in older adults, and from 7+/-1% to 3+/-1% in peripheral arterial disease patients (all, P<0.001). Furthermore, we found positive correlations between plasma Hcy and ADMA concentrations (P=0.03, r=0.450), as well as ADMA and flow-mediated vasodilatation (P=0.002, r=0.623). CONCLUSIONS: Our results suggest that experimental hyperhomocyst(e)inemia leads to accumulation of the endogenous NO synthase inhibitor ADMA, accompanied by varying degrees of endothelial dysfunction according to the preexisting state of cardiovascular health.

Adult↗
PubMed2003

Gender differences in perception of PAD: a pilot study.

Patients with peripheral arterial disease (PAD) report profound limitations in all domains of quality of life that are worse than those for patients with chronic pulmonary disease and moderate to severe heart failure. While claudication has detrimental effects on quality of life, little is understood about the factors that influence quality of life and whether these determinants are similar for men and women with PAD and claudication. The purpose of the present investigation was to evaluate the effect of claudication on quality of life in 71 men and 26 women (mean age 72 and 73 years respectively) with PAD. Disease severity as assessed by ankle brachial index (ABI) and community-based walking was similar for men and women, although men reported greater comorbid conditions than women. Despite the similarity in disease severity, women reported decreased physical functioning (p = 0.01), more bodily pain (p = 0.04) and greater mood disturbance (p = 0.012) than men. Claudication and PAD had a greater impact on women than on men and may result from the higher prevalence of mood disturbance and bodily pain reported by women.

Aged↗
PubMedDate not supplied

Peripheral arterial disease in older adults: management of cardiovascular disease risk factors.

Patients with peripheral arterial disease experience significant functional limitations due to ischemic symptoms (claudication) and are at high risk for cardiovascular disease morbidity and mortality resulting from untreated cardiovascular disease risk factors and aggressive atherosclerosis. Peripheral arterial disease is commonly undiagnosed and cardiovascular disease risk factors are frequently untreated in this population. The increased risk associated with peripheral arterial disease necessitates greater emphasis on detection and management, not only to improve survival but to improve functional capacity and quality of life. This article briefly describes the detection and medical management with emphasis on lifestyle modification for elders with peripheral arterial disease.

Aged↗
PubMedDate not supplied

Quantifying smoking cessation outcomes: from The Women's Initiative for Nonsmoking Study (X): methodological implications.

BACKGROUND: Classification of smoking status has a major impact on the conclusions drawn from smoking cessation intervention research, yet few studies have addressed this critical issue. OBJECTIVES: The aim of this study was to compare three classifications (naïve, optimistic, and pessimistic) of smoking cessation outcomes or smoking status from the Women's Initiative for Nonsmoking Study (WINS). METHODS: This is a longitudinal prospective study nested within a randomized clinical trial (RCT) design of WINS, an RCT of 277 women over the age of 18 years who reported smoking cigarettes continuously for 1 month prior to a cardiovascular event requiring hospital admission. Women were randomized to either the usual care group (UC) or the intervention group (IG). Recruitment for WINS occurred between October 1996 and December 1998 in 10 hospitals in the San Francisco Bay area. Follow-up data on smoking status was obtained from the UC and the IG using a structured telephone interview at 6 and 12 months from baseline and was confirmed by family members and salivary cotinine levels. RESULTS: Seven-day point prevalence(self-report of not smoking in the past 7 days; "not even a puff") using the naïve (the most liberal) classification yields a greater number of nonsmokers than the pessimistic or most conservative classification (cotinine level verification of smoking status). The classification of smoking status also affects time to continuous smoking. The pessimistic classification results in the shortest time to continuous smoking, whereas the opposite is observed with the naïve classification. DISCUSSION: It is important to critically evaluate the underlying assumptions made by study investigators when measuring and reporting smoking status. The classification of smoking status and the selection of analysis, meaning point prevalence versus survival analysis, affect study results and contribute to the variability observed in the research findings of smoking cessation intervention trials and the challenges faced in making appropriate comparisons across studies.

Adult↗