Biomedical subjects

Linda R Peterson

Publications and source records attributed to Linda R Peterson.

17 recordsLinked to original sources

PubMed2006

Prospective comparison of ventilatory equivalent versus peak oxygen consumption in predicting outcomes of patients with heart failure.

In patients with heart failure (HF), peak exercise oxygen consumption (VO2) is an important prognostic tool on which critical clinical decisions are made. However, recent retrospective data have suggested that ventilatory equivalent (VE = ventilation [liters per minute]/VO2 [liters per minute]) may be a stronger predictor of outcomes than VO2 in patients with HF on modern medical therapies. We prospectively collected baseline demographics, cardiovascular history, hemodynamics, and exercise ventilatory data from 221 consecutive patients with HF who underwent treadmill exercise VO2 testing. The composite primary end point was death or heart transplantation. Mean follow-up was 508 days, during which 27 events occurred (13 deaths and 14 transplantations). One-year event-free survival was 88% (n = 104 with 1-year follow-up). Mean age was 49 years, 68% were men, 84% were taking beta blockers, 82% were taking angiotensin-converting enzyme inhibitors, and 21% had an implantable cardioverter-defibrillator. Mean VO2 was 16 +/- 5 ml/kg/min. Mean VE was 47.4 +/- 15.2. Univariate predictors of events included lower VO2 (p <0.0001), higher heart rate at rest (p = 0.05), and presence of an implantable cardioverter-defibrillator (p = 0.024). Higher VE (p = 0.10) and lower maximum systolic blood pressure (p = 0.09) were of borderline significance. Age, gender, HF etiology or severity, and other ventilatory parameters were not significant predictors. Multivariate models that incorporated VE, VO2, or their combination confirmed VO2 as an independent predictor of event-free survival (p < or =0.0002); VE did not independently predict outcomes. Other independent predictors were higher heart rate at rest (p < or =0.02) and presence of an implantable cardioverter-defibrillator (p < or =0.04). In conclusion, peak VO2, but not VE, predicts clinical outcomes of patients with HF who are treated with contemporary medical therapies.

Disease Progression↗

PubMed2006

Increased myocardial fatty acid metabolism in patients with type 1 diabetes mellitus.

OBJECTIVES: The purpose of this study was to determine if myocardial fatty acid utilization (MFAU) and myocardial fatty acid oxidation (MFAO) are increased in diabetic patients. BACKGROUND: Experimental models of diabetes mellitus demonstrate that MFAU and MFAO are increased, and that this dependence on myocardial fatty acid metabolism may be detrimental to cardiac function. Whether similar metabolic changes occur in humans with diabetes mellitus is unclear. METHODS: Eleven healthy non-diabetic control patients (5 women, ages 25 +/- 5 years) and 11 otherwise healthy patients with type 1 diabetes mellitus (T1DM) (8 women, ages 36 +/- 10 years, HbA1c 8.4 +/- 1.9%) underwent positron emission tomography for the determination of myocardial blood flow (MBF); myocardial oxygen consumption (MVO2); myocardial glucose utilization (MGU); and MFAU, MFAO, and %MFAO. RESULTS: Plasma lactate, insulin, and MBF levels were similar between the two groups. However, plasma glucose (5.71 +/- 0.98 mumol/ml vs. 5.28 +/- 0.65 mumol/ml, p = 0.04), free fatty acid levels (0.60 +/- 0.24 mumol/ml vs. 0.19 +/- 0.07 mumol/ml, p < 0.0001), and MVO2 (6.64 +/- 2.21 vs. 4.51 +/- 1.39 mumol/g/min, p = 0.007) levels were higher in the T1DM subjects. Furthermore, compared with control patients, T1DM subjects exhibited higher MFAU (213 +/- 135 nmol/g/min vs. 57 +/- 28 nmol/g/min, p = 0.0004), MFAO (206 +/- 131 nmol/g/min s. 50 +/- 26 nmol/g/min, p = 0.0002), and %MFAO (94 +/- 6% vs. 81 +/- 19%, respectively, p = 0.04). In contrast, MGU was lower in T1DM subjects than in controls (207 +/- 108 nmol/g/min vs. 403 +/- 191 nmol/g/min, p = 0.0008). CONCLUSIONS: Humans with diabetes mellitus exhibit increased MFAU and MFAO and reduced MGU consistent with observations obtained in experimental models of diabetes.

Adult↗

PubMed2006

Obesity and insulin resistance: effects on cardiac structure, function, and substrate metabolism.

It is widely recognized that obesity and insulin resistance can contribute to an increased risk of coronary disease, but it has also become increasingly apparent that they may contribute directly to cardiac dysfunction even in the absence of significant coronary disease. Recently, obesity, which is frequently accompanied by insulin resistance, has been independently related to clinically diagnosed heart failure. Thus, there is renewed interest in the pathophysiology of myocardial disease related to obesity and insulin resistance, as well as in the specific cellular mechanisms by which obesity may cause detrimental cardiac structural and functional changes. Alterations in hemodynamics, plasma volume, neurohormonal status, and myocardial substrate metabolism all appear to contribute to these changes. Improving our understanding of cardiac dysfunction related to obesity and insulin resistance may provide clues for new strategies to prevent and treat this alarmingly prevalent condition.

Animals↗

PubMed2006

Alterations in left ventricular structure and function in type-1 diabetics: a focus on left atrial contribution to function.

This study was designed to determine the effects of type 1 diabetes mellitus (T1DM) on left ventricular (LV) and particularly left atrial (LA) structure and function. We evaluated 88 non-obese subjects: 44 with T1DM, 44 age- and gender-matched normal controls (age 39 +/- 11 years). LV and LA structure and function were quantified using two-dimensional echocardiography, pulse-wave Doppler, and tissue Doppler imaging, including early and late diastolic myocardial velocities (Em global and Am global, respectively). The T1DM subjects averaged higher heart rate, relative wall thickness, and ejection fraction, and lower indexed end-systolic volume than normal controls (P < .001, P < .05, P = .01, and P < .05, respectively). T1DM was related to A wave velocity, Am global, A wave integral, LA ejection fraction, and LA systolic ejection fraction (P < .01, P < .05, P < .0005, P < .001, and P < .0005, respectively). In multivariate analyses, T1DM was an independent predictor of the A wave integral, LA ejection fraction, and LA systolic ejection fraction (P < .01, P < .01, and P < .005, respectively). Thus, despite increased relative wall thickness, LV systolic function is increased and early diastolic filling is normal in T1DM subjects; however, they possess changes in LA transport function suggesting increased reliance on LA contribution to LV filling.

Adolescent↗

PubMed2005

Aerobic power and insulin action improve in response to endurance exercise training in healthy 77-87 yr olds.

Previous studies have demonstrated that frail octogenarians have an attenuated capacity for cardiovascular adaptations to endurance exercise training. In the present study, we determined the magnitude of cardiovascular and metabolic adaptations to high-intensity endurance exercise training in healthy, nonfrail elderly subjects. Ten subjects [8 men, 2 women, 80.3 yr (SD2.5)] completed 10-12 mo (108 exercise sessions) of a supervised endurance exercise training program consisting of 2.5 sessions/wk (SD 0.2), 58 min/session (SD 6), at an intensity of 83% (SD 5) of peak heart rate. Primary outcomes were maximal attainable aerobic power [peak aerobic capacity (Vo(2peak))]; serum lipids, oral glucose tolerance, and insulin action during a hyperglycemic clamp; body composition by dual-energy X-ray absorptiometry, and energy expenditure using doubly labeled water and indirect calorimetry. The training program resulted in an increase in Vo(2peak) of 15% (SD 7) [22.9 (SD 3.3) to 26.2 ml.kg(-1).min(-1) (SD 4.0); P < 0.0001]. Favorable lipid changes included reductions in total cholesterol (-8%; P = 0.002) and LDL cholesterol (-10%; P = 0.003), with no significant change in HDL cholesterol or triglycerides. Insulin action improved, as evidenced by a 29% increase in glucose disposal rate relative to insulin concentration during the hyperglycemic clamp. Fat mass decreased by 1.8 kg (SD 1.4) (P = 0.003); lean mass did not change. Total energy expenditure increased by 400 kcal/day because of an increase in physical activity. No change occurred in resting metabolism. In summary, healthy nonfrail octogenarians can adapt to high-intensity endurance exercise training with improvements in aerobic power, insulin action, and serum lipid and lipoprotein risk factors for coronary heart disease; however, the adaptations in aerobic power and insulin action are attenuated compared with middle-aged individuals.

Adaptation, Physiological↗

PubMed2004

Effect of obesity and insulin resistance on myocardial substrate metabolism and efficiency in young women.

BACKGROUND: Obesity is a risk factor for impaired cardiac performance, particularly in women. Animal studies suggest that alterations in myocardial fatty acid metabolism and efficiency in obesity can cause decreased cardiac performance. In the present study, we tested the hypothesis that myocardial fatty acid metabolism and efficiency are abnormal in obese women. METHODS AND RESULTS: We studied 31 young women (body mass index [BMI] 19 to 52 kg/m2); 19 were obese (BMI >30 kg/m2). Myocardial oxygen consumption (MVO2) and fatty acid uptake (MFAUp), utilization (MFAU), and oxidation (MFAO) were quantified by positron emission tomography. Cardiac work was measured by echocardiography, and efficiency was calculated as work/MVO2. BMI correlated with MVO2 (r=0.58, P=0.0006), MFAUp (r=0.42, P<0.05), and efficiency (r=-0.40, P<0.05). Insulin resistance, quantified by the glucose area under the curve (AUC) during an oral glucose tolerance test, correlated with MFAUp (r=0.55, P<0.005), MFAU (r=0.62, P<0.001), and MFAO (r=0.58, P<0.005). A multivariate, stepwise regression analysis showed that BMI was the only independent predictor of MVO2 and efficiency (P=0.0005 and P<0.05, respectively). Glucose AUC was the only independent predictor of MFAUp, MFAU, and MFAO (P<0.05, <0.005, and <0.005, respectively). CONCLUSIONS: In young women, obesity is a significant predictor of increased MVO2 and decreased efficiency, and insulin resistance is a robust predictor of MFAUp, MFAU, and MFAO. This increase in fatty acid metabolism and decrease in efficiency is concordant with observations made in experimental models of obesity. These metabolic changes may play a role in the pathogenesis of decreased cardiac performance in obese women.

Adult↗

PubMed2004

Comparison of effects of exercise and diuretic on left ventricular geometry, mass, and insulin resistance in older hypertensive adults.

To compare the effects of exercise training and hydrochlorothiazide on left ventricular (LV) geometry and mass, blood pressure (BP), and hyperinsulinemia in older hypertensive adults, we studied 28 patients randomized either to a group (age 66.4 +/- 1.3 yr; n = 16) that exercised or to a group (age 65.3 +/- 1.2 yr; n = 12) that received hydrochlorothiazide for 6 mo. Endurance exercise training induced a 15% increase in peak aerobic power. The reduction in systolic BP was twofold greater with thiazide than with exercise (26.6 +/- 12.2 vs. 11.5 +/- 10.9 mmHg). Exercise and thiazide reduced LV wall thickness, LV mass index (14% in each group), and the LV wall thickness-to-radius ratio (h/r) similarly (exercise: before 0.48 +/- 0.2, after 0.42 +/- 0.01; thiazide: before 0.47 +/- 0.04, after 0.40 +/- 0.04; P = 0.017). The reductions in systolic BP and h/r were correlated in the exercise group (r = 0.70, P = 0.005) but not in the thiazide group. Exercise training reduced glucose-stimulated hyperinsulinemia (before: 13.65 +/- 2.6 vs. 9.84 +/- 1.5 mU.ml(-1).min; P = 0.04) and insulin resistance. Thiazide did not affect plasma insulin levels. The results suggest that although exercise is less effective in reducing systolic BP than thiazide, it can induce regression of LV hypertrophy similar in magnitude to thiazide. Unlike hydrochlorothiazide, exercise training can improve insulin resistance and aerobic capacity in older hypertensive people.

Aged↗

PubMed2004

Alterations in left ventricular structure and function in young healthy obese women: assessment by echocardiography and tissue Doppler imaging.

OBJECTIVES: This study was designed to determine the effects of obesity on left ventricular (LV) structure and function in young obese women. BACKGROUND: Severe prolonged obesity in older adults results in increased plasma volume, eccentric LV hypertrophy, and systolic and diastolic dysfunction. Obese women are at increased risk for the development of heart failure. However, the effects of the obesity on cardiac structure and function in young, otherwise-healthy women are controversial. METHODS: Fifty-one women were evaluated: 20 were obese (body mass index [BMI] > or =30 kg/m(2)) and 31 were non-obese (BMI <30 kg/m(2)). Left ventricular structure and systolic and diastolic function were assessed by two-dimensional echocardiography and tissue Doppler imaging, including the load-independent systolic myocardial velocity (Sm global) and early diastolic myocardial velocity (Em global), respectively. The effects of BMI on LV structure and function were assessed using multivariate regression analyses. RESULTS: Obese women had higher end-diastolic septal and posterior wall thickness, LV mass, and relative wall thickness than non-obese women; BMI values showed significant correlations with these variables (r = 0.58, p < 0.0001; r = 0.50, p < 0.0002; r = 0.52, p < 0.0001, and r = 0.40, p < 0.005, respectively). The Sm global and Em global were lower in obese women, suggesting systolic and diastolic function are decreased; both were negatively correlated with BMI (r = -0.43, p <. 002 and r = -0.61, p < 0.0001, respectively). Multivariate analysis showed BMI was the only independent predictor of relative wall thickness, Sm global, and Em global. CONCLUSIONS: Obesity in young otherwise-healthy women is associated with concentric LV remodeling and decreased systolic and diastolic function. These early abnormalities in LV structure and function may have important implications for explaining the myocardial dysfunction that is associated with increased cardiovascular morbidity and mortality caused by obesity.

Adult↗

PubMed2004

Absence of left ventricular and arterial adaptations to exercise in octogenarians.

Recent evidence suggests that octogenarians exhibit attenuated adaptations to training with a small increase in peak O2 consumption (VO2) that is mediated by a modest improvement in cardiac output without an increase in arteriovenous O2 content difference. This study was designed to determine whether diminished increases in peak VO2 and cardiac output in the octogenarians are associated with absence of left ventricular and arterial adaptations to exercise training. We studied 22 octogenarians (81.9 +/- 3.7 yr, mean +/- SD) randomly assigned a group that exercised at an intensity of 82.5 +/- 5% of peak heart rate for 9 mo and 14 (age 83.1 +/- 4.1) assigned to a control group. Peak VO2 increased 12% in the exercise group but decreased slightly (-7%) in the controls. The exercise group demonstrated significant but small decreases in the heart rate (6%, P = 0.002) and the rate-pressure product (9%, P = 0.004) during submaximal exercise at an absolute work rate. Training induced no significant changes in the left ventricular size, geometry (wall thickness-to-radius ratio), mass, and function assessed with two-dimensional echocardiography or in arterial stiffness evaluated with applanation tonometry. Data suggest that the absence of cardiac and arterial adaptations may in part account for the limited gain in aerobic capacity in response to training in the octogenarians.

Adaptation, Physiological↗

PubMed2003

Attenuation of cardiovascular adaptations to exercise in frail octogenarians.

To determine the mechanisms underlying increased aerobic power in response to exercise training in octogenarians, we studied mildly frail elderly men and women randomly assigned to an exercise group (n = 22) who participated in a training program of 6 mo of physical therapy, strength training, and walking followed by 3 mo of more intense endurance exercise at 78% of peak heart rate or a control sedentary group (n = 24). Peak O2 consumption (V(O2 peak)) increased 14% in the exercise group (P < 0.0001) but decreased slightly in controls. Training induced 14% increase (P = 0.027) in peak exercise cardiac output (Q), determined via acetylene re-breathing, and no change in arteriovenous O2 content difference. The increase in Q was mediated by increases in heart rate (P = 0.009) and probably stroke volume (P = 0.096). Left ventricular stroke work also increased significantly. In the men, the increase in V(O2 peak) was exclusively due to a large increase in peak Q (22%). In the women, the gain in V(O2 peak) was due to small increases in Q and O2 extraction from skeletal muscles. Pulse pressure normalized for stroke volume and arterial elastance during peak effort did not change with training. Controls showed no changes. The results suggest that, although frail octogenarians have a diminished capacity for improvement in aerobic power in response to exercise training, this adaptation is mediated mostly by an increase in Q during peak effort. Furthermore, Q likely plays a greater role in the adaptive increase in V(O2 peak) in old men than old women.

Adaptation, Physiological↗

PubMed2003

The effect of beta-adrenergic blockers on the prognostic value of peak exercise oxygen uptake in patients with heart failure.

OBJECTIVES: Our aim was to determine the effect of beta-adrenergic blockade on the prognostic value of peak oxygen consumption testing in patients with heart failure. BACKGROUND: Peak oxygen consumption has been shown to be a useful prognostic tool in patients with heart failure. However, studies demonstrating the utility of peak oxygen consumption were conducted before beta-blocker therapy became widespread. Thus, our objective was to determine the effect of beta-blockers on the prognostic value of peak oxygen consumption in patients with heart failure. METHODS: Actuarial, anthropomorphic, hemodynamic and exercise ventilatory data were collected from 369 patients with heart failure. Death and orthotopic heart transplants were the events tracked. Patients were divided into those taking beta-blockers and those not taking them. Event-free survival days were calculated. RESULTS: One hundred ninety-nine patients on beta-blockers and 170 not on beta-blockers were studied. There were 40 orthotopic heart transplants and 82 deaths during follow-up. Peak oxygen consumption (milliliters per kilogram per minute) trended toward being an independent predictor of event-free survival (p = 0.055). In patients on and not on beta-blockers, a peak oxygen consumption of >14 ml/kg.min was associated with a 1-year event rate of approximately half of that associated with a peak oxygen consumption </=14 ml/kg x min. However, for every level of peak oxygen consumption, the event rate was lower in the group taking beta-blockers. CONCLUSIONS: Beta-blocker status does not change the predictive power of peak oxygen consumption in patients with heart failure, but beta-blocker status is important to consider when using peak oxygen consumption to predict event-free survival in patients with heart failure.

Adrenergic beta-Antagonists↗

PubMed2003

Timing of cardiac transplantation in patients with heart failure receiving beta-adrenergic blockers.

BACKGROUND: Previous work shows that patients with heart failure patients who have peak oxygen consumption (VO2 peak) >14 ml/kg/min do not derive a survival benefit from cardiac transplantation. However, this was shown before beta-blocker therapy for patients with systolic heart failure became common, and beta-blockers improve survival in patients with heart failure without changing VO(2) peak. Our purpose was to re-evaluate the utility of VO(2) peak >14 ml/kg/min as an indicator of the need for cardiac transplantation in patients with heart failure who are taking beta-blockers. METHODS: Actuarial, hemodynamic, and exercise ventilatory data were collected from 540 patients with heart failure, 256 of whom were taking beta-blockers. We tracked death and cardiac transplantation. We stratified the percentage of patients event-free 1 and 3 years after VO(2) peak study by their VO(2) peak and beta-blocker status, and compared 1- and 3-year post-transplant survival (United Network of Organ Sharing [UNOS] data). We also compared total mortality for the patients with heart failure as stratified by beta-blocker stats and VO(2) peak (excluding the 42 who underwent transplantation) with UNOS post-transplant survival. RESULTS: Patients with heart failure who were receiving beta-blockers and whose VO(2) peak was > or =12 ml/kg/min had greater 1- and 3-year event-free survival rates (95% confidence intervals, 92.6%-96.6% and 85.8%-96.0%) than did post-transplant patients (83.9%-86.3% and 75.4%-76.6%). However, in patients with heart failure not taking beta-blockers, VO(2) peak <14 ml/kg/min was associated with worse 3-year survival (38.9 - 62.1%) than that for post-transplant patients. Excluding the 42 patients with heart failure in our study who underwent transplantation and then evaluating survival of the remaining patients with heart failure (not event-free survival) did not substantially change these results. CONCLUSIONS: Patients with heart failure who are receiving beta-blockers do not derive a survival advantage at 1 and 3 years after cardiac transplantation if VO(2) peak is > or =12 ml/kg/min. Patients not taking beta-blockers whose VO(2) peak is <14 ml/kg/min have superior survival with cardiac transplantation.

Adrenergic beta-Antagonists↗

PubMed2003

Myocardial fatty acid metabolism: independent predictor of left ventricular mass in hypertensive heart disease.

The expression of myocardial fatty acid beta-oxidation enzymes is downregulated at the gene transcriptional level in animal models of left ventricular hypertrophy and of heart failure. Humans with idiopathic dilated cardiomyopathy have decreased myocardial fatty acid oxidation. The extent to which molecular mechanisms, such as a reduction in myocardial fatty acid oxidation, regulate the cardiac hypertrophic response in humans in vivo is unknown. Positron emission tomography was used to measure myocardial blood flow, oxygen consumption, fatty acid utilization, and oxidation in two groups of patients: (1) hypertensive left ventricular hypertrophy (n=19; left ventricular mass, 211+/-39 g; left ventricular ejection fraction, 67+/-4%) and (2) left ventricular dysfunction (n=9; left ventricular mass, 210+/-36 g; left ventricular ejection fraction, 31+/-10%); these were compared with a normal control group (n=36; left ventricular mass, 139+/-25 g; left ventricular ejection fraction, 66+/-6%). Left ventricular mass showed significant correlation with gender, diastolic and systolic blood pressure, myocardial fatty acid uptake, utilization and oxidation, myocardial blood flow, body mass index, and left ventricular ejection fraction (all P<0.02). Independent predictors of increased left ventricular mass were male gender (r=0.38, P<0.001), myocardial fatty acid oxidation (r=-0.24, P<0.018), systolic blood pressure (r=0.41, P<0.001), and left ventricular ejection fraction (r=-0.29, P=0.005). Thus, myocardial fatty acid metabolism is an independent predictor of left ventricular mass in hypertension and in left ventricular dysfunction. The extent to which reduced myocardial fatty acid metabolism affects cardiovascular morbidity and mortality and whether pharmacologic modulation results in improved outcomes remains to be determined.

Adult↗

PubMed2002

Peak exercise stroke volume: associations with cardiac structure and diastolic function.

One of the most debilitating effects of primary aging is the decline in aerobic exercise capacity. One of its causes is an age-related decline in peak exercise stroke volume. This study's main purpose was to determine the cardiovascular adaptations to aging that most influence peak exercise stroke volume in the elderly. We hypothesized that increased left ventricular (LV) filling and mild concentric LV remodeling would be associated with an increase in peak exercise stroke volume corrected for lean body mass (LBM) and that an increased augmentation index (AI), which is a marker of arterial stiffness, would be associated with a decrease. A second aim was to determine the adaptations to aging that most influence LV concentric remodeling in the elderly. We hypothesized that AI would be a predictor of LV mass/LBM and the LV posterior wall thickness-to-LV radius ratio (h/r). We performed a cross-sectional study of cardiac and vascular adaptations to aging in 52 sedentary, elderly subjects. LV filling [as measured by the early-to-late transmitral flow velocity ratio (E/A)] was inversely correlated with and was an independent predictor of peak exercise stroke volume/LBM and was also a predictor of LV remodeling. AI was a predictor of LV remodeling (LV mass/LBM) but not of peak exercise stroke volume/LBM. We conclude that 1) maintenance of LV filling (E/A <1) is associated with a higher peak exercise stroke volume/LBM in very elderly subjects and thus may be a useful adaptation that enhances stroke volume during peak exercise, 2) LV remodeling and AI are less influential on peak exercise stroke volume/LBM, and 3) AI was the most important predictor of LV remodeling.

Adaptation, Physiological↗

PubMedDate not supplied

Impact of hormone replacement on myocardial fatty acid metabolism: potential role of estrogen.

BACKGROUND: Estrogen increases fatty acid utilization and oxidation and may decrease glucose use in human skeletal muscle, whereas these effects are attenuated by progesterone. Whether these ovarian hormones exhibit similar effects on myocardial metabolism is unknown. METHODS AND RESULTS: Myocardial blood flow and oxygen consumption, as well as glucose and fatty acid metabolism, were examined retrospectively by use of positron emission tomography in 24 postmenopausal women receiving estrogen (n = 7), estrogen plus progesterone (n = 8), or no hormone replacement (n = 9) and in 22 age-matched men. Myocardial blood flow was higher in women regardless of hormone replacement status. Myocardial oxygen consumption was higher in women taking estrogen only when compared with men (7.3 +/- 1.6 micromol.g(-1).min(-1) vs 4.6 +/- 1.2 micromol.g(-1).min(-1), P < .001). Glucose utilization was not affected by gender or hormone replacement. Whereas fatty acid levels and the degree of myocardial fatty acid uptake were not distinguished by gender or hormone use, myocardial fatty acid utilization was higher in women taking estrogen when compared with men (259 +/- 68 nmol.g(-1).min(-1) vs 176 +/- 50 nmol.g(-1).min(-1), P = .01) and trended higher when compared with women not receiving hormonal therapy (185 +/- 46 nmol.g(-1).min(-1), P = .07) but was not different from that of women taking estrogen plus progesterone (205 +/- 58 nmol.g(-1).min(-1), P = not significant). CONCLUSIONS: In postmenopausal women, estrogen use is associated with increased myocardial fatty acid utilization. Thus, when the cardiac effects of hormone replacement therapy are being assessed, alterations in myocardial substrate metabolism should be considered.

Aged↗

PubMedDate not supplied

Effects of soy protein isolate and moderate exercise on bone turnover and bone mineral density in postmenopausal women.

OBJECTIVE: The aim of this study was to assess the independent and additive effects of soy protein isolate (SPI) and moderate-intensity exercise (EX) on bone turnover and bone mineral density (BMD). DESIGN: This study used a placebo-controlled, double-blind (soy), randomized 2 (SPI vs milk protein isolate [MPI]) x 2 (EX vs no EX) design. Sixty-one postmenopausal women were randomized, and 43 (62 +/- 5 y) completed the 9-month intervention (SPI, n = 10; MPI, n = 12; SPI + EX, n = 11; MPI + EX, n = 10). Serum C-terminal cross-linked telopeptides of type I collagen and serum bone-specific alkaline phosphatase were measured as markers of bone resorption and formation, respectively. BMD was measured by dual-energy x-ray absorptiometry. RESULTS: At 9 months, SPI reduced serum C-terminal cross-linked telopeptides (-13.3% +/- 15.3% vs -1.5% +/- 21.0%; P = 0.02) and serum bone-specific alkaline phosphatase (-4.7% +/- 14.7% vs 6.5% +/- 17.7%; P = 0.02) compared to milk protein isolate. EX attenuated the reduction in serum C-terminal cross-linked telopeptides (-1.9% +/- 21.6% vs -12.4% +/- 15.3%; P = 0.04); however, no EX effects were apparent in serum bone-specific alkaline phosphatase at 9 months (2.8% +/- 16.1% vs -1.0% +/- 18.3%; P = 0.28). Neither SPI nor EX affected BMD at any site; however, change in BMD was related to change in fat mass (r = 0.40, P < 0.05). CONCLUSIONS: In postmenopausal women (1) SPI reduces bone turnover with no impact on BMD over 9 months; (2) moderate-intensity endurance exercise training did not favorably alter bone turnover and had no impact on BMD; and (3) there were no additive effects of soy and exercise on bone turnover or BMD.

Absorptiometry, Photon↗

PubMedDate not supplied

The safety of performing diagnostic cardiac catheterizations in a mobile catheterization laboratory at primary care hospitals.

The benefits of mobile cardiac catheterization laboratories include keeping patients closer to their families, communities, local hospitals, and primary care physicians while receiving services comparable to those available at tertiary centers. However, there are very few studies regarding the safety of performing cardiac catheterization in mobile laboratories at remote locations. Thus, the authors performed an observational study of 1,775 consecutive patients undergoing a diagnostic cardiac catheterization in a mobile catheterization laboratory at primary care hospitals served by the Appleton Heart Institute (AHI) from August 1, 1991, to December 31, 1998. Twenty-three percent (1,775/7,637) of all AHI diagnostic cases in this time period were performed in the mobile catheterization laboratory. Urgent transfer to the tertiary care facility via ambulance or helicopter was used for 2.3% of patients (n = 41). The overall complication rate was 1.2% (n = 21). Of the patients who underwent cardiac catheterization in the mobile laboratory, 32.6% (n = 579) were subsequently referred for interventional or surgical revascularization. There were no deaths. Cardiac catheterizations can be performed safely in a mobile laboratory at primary care hospitals, provided that immediate transfer is available for those in need of urgent intervention or revascularization and that unstable patients are not studied in the mobile laboratory.

Adult↗