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Biomedical subjects

Michael J LaMonte

Publications and source records attributed to Michael J LaMonte.

At least 19 recordsLinked to original sources
PubMed2026

Gut bacteria associated with an atherogenic TMAO-dietary pattern and choline-rich foods among aging women.

BACKGROUND AND AIMS: Choline can be metabolized by gut bacteria with a choline utilization gene, CutC, as identified through genome sequencing studies. This metabolism produces trimethylamine, the precursor to the atherosclerotic metabolite trimethylamine N-oxide (TMAO). Bacterial species involved in trimethylamine production in free-living humans have been under-investigated. We previously developed the TMAO dietary pattern (TMAO-DP), which is predictive of plasma TMAO and choline. We evaluated associations between the TMAO-DP, dietary choline, and choline-rich foods (fish, red meat, eggs) with the abundance of species with CutC. We also explored associations between the TMAO-DP and microbiome diversity. METHODS AND RESULTS: This cross-sectional analysis included 287 women (mean age = 79.6 years) from the Women's Health Initiative. Diet was assessed using a food frequency questionnaire. Stool samples were collected and the V3-V4 regions of the 16S ribosomal RNA were sequenced. Adjusted linear regression models evaluated associations between the TMAO-DP with the CLR-transformed abundance of species with CutC and with alpha-diversity indices. For beta-diversity, PERMANOVA examined measures of Aitchison distance within and between quartiles of the TMAO-DP. Associations between dietary choline and choline-rich foods with the abundance of species were evaluated using linear regression. The TMAO-DP was associated with Acidaminococcus intestini [Beta (SE): 0.23 (0.09), p-value = 0.035] and Desulfovibrio desulfuricans [Beta (SE): 0.16 (0.6), p = 0.035]. The TMAO-DP was not associated with alpha- or beta-diversity. CONCLUSION: This study provides evidence that Desulfovibrio desulfuricans and Acidaminococcus intestini, two species identified as having CutC by gene sequencing, may produce trimethylamine from diet in free-living women.

Humans↗
PubMed2006

Coronary artery calcium, exercise tolerance, and CHD events in asymptomatic men.

Coronary artery calcium (CAC) scores >/=100 are predictive of CHD events in asymptomatic men. Exercise tolerance of >/=10METs predicts lower event rates in CHD patients; however, its relationship with events in individuals with subclinical atherosclerosis is less known. Participants were 710 asymptomatic men from the Aerobics Center Longitudinal Study whose exercise tolerance (ET) was quantified (<10 or >/=10METs) and whose CAC score was >/=100 as measured by electron beam tomography. During 3.5 years of follow-up 59 CHD events occurred. The age-adjusted hazard ratio (HR) of CHD events was 0.26 (95% CI=0.15-0.45) in men whose ET was >/=10METs compared with men whose ET was <10METs. Adjustment for CHD risk factors and abnormal exercise ECG did not change the association between ET and CHD. The extent of underlying atherosclerosis did not influence the association between ET and CHD; for example, the HR for CHD events in the >/=10MET group among men with CAC scores <400 and >/=400 was 0.16 (95% CI=0.05-0.56) and 0.23 (95% CI=0.11-0.46), respectively. In asymptomatic men with subclinical coronary atherosclerosis, an ET of >/=10METs identifies patients at lower risk for manifest CHD.

Calcium↗
PubMed2006

Cardiorespiratory fitness, macronutrient intake, and the metabolic syndrome: the Aerobics Center Longitudinal Study.

OBJECTIVE: This study examines the cross-sectional associations between cardiorespiratory fitness and the metabolic syndrome with adjustment for macronutrient intake from 3-day dietary records. DESIGN: Cross-sectional study. SUBJECTS/SETTING: Women and men who had a comprehensive medical examination, including a symptom-limited maximal treadmill exercise test, and completed 3-day dietary records at the Cooper Clinic, Dallas, TX. MAIN OUTCOME MEASURES: Metabolic syndrome as defined by the National Cholesterol Education Program Adult Treatment Panel III criteria. STATISTICAL ANALYSES PERFORMED: Analysis of variance was used to examine differences in continuous data. General linear analysis was used to examine linear trends. Mantel-Haenszel chi(2) analyses were used to examine differences in categorical data. Logistic regression was used to estimate odds ratios and 95% confidence intervals. RESULTS: After adjusting for sex and age, cardiorespiratory fitness was inversely associated with the prevalence of metabolic syndrome (P<0.001). Adjustment for macronutrient intake and other potential confounding variables did not alter the association between cardiorespiratory fitness and prevalent metabolic syndrome. CONCLUSIONS: Cardiorespiratory fitness is inversely associated with the prevalence of metabolic syndrome. Patients should be encouraged to increase their physical activity to decrease their risk for metabolic syndrome and coronary heart disease.

Adult↗
PubMed2006

Physical activity, cardiorespiratory fitness, and adiposity: contributions to disease risk.

PURPOSE OF REVIEW: To discuss assessing physical activity, cardiorespiratory fitness, and adiposity in the context of examining their prospective joint associations with mortality in cohort studies. RECENT FINDINGS: Accurate and comprehensive assessment of free-living physical activity patterns and related energy expenditure is difficult. Cardiorespiratory fitness is a reproducible measure associated with recent physical activity patterns; however, its assessment has been considered impractical in epidemiologic studies. Likewise, objective measures of adiposity and fat distribution often are not feasible in large studies. Thus, physical activity and adiposity exposures typically are quantified using self-reports of physical activity habits and of height and weight to compute body mass index. When considered jointly, adults with higher levels of fitness or reported physical activity tend to have lower mortality risk than their unfit and inactive peers within the same body mass index group. SUMMARY: Accumulating evidence suggests that higher physical activity or fitness attenuates the health risks of obesity. Available data largely are based on crude measures of physical activity and body habitus, which may obscure their association with disease risk. Accurate measures must be included in epidemiologic studies to improve estimation of the independent and joint associations of these exposures with health outcomes.

Adipose Tissue↗
PubMed2005

Cardiorespiratory fitness is an independent predictor of hypertension incidence among initially normotensive healthy women.

The authors examined the association between cardiorespiratory fitness and incident hypertension in women who were normotensive and free of cardiovascular disease at baseline in the Aerobics Center Longitudinal Study (Dallas, Texas), 1970-1998. A total of 4,884 women performed a maximal treadmill exercise test and completed a follow-up health survey. During an average follow-up of 5 years, 157 incident cases of self-reported, physician-diagnosed hypertension were identified from the health surveys. The cumulative incidence of hypertension was 3.2%. Compared with the rates of low-fit women, crude hypertension rates were 60% and 79% lower among women in the moderate and high fitness categories, respectively (p < 0.001). After adjustment for several potential confounders, the odds ratios for hypertension were 1.0, 0.61 (95% confidence interval (CI): 0.30, 1.21), and 0.35 (95% CI: 0.17, 0.73) in low-, moderately, and highly fit women, respectively (p(trend) < 0.01). Each 1-metabolic equivalent increment in treadmill performance was, on average, associated with a 19% (95% CI: 10, 27; p < 0.001) lower odds of incident hypertension. The pattern and strength of association between fitness and hypertension persisted in analyses stratified on body mass index, age, and the presence of prehypertension at baseline. An active lifestyle should be promoted for the primary prevention of hypertension in women.

Adult↗
PubMed2005

Cardiorespiratory fitness and body mass index as predictors of cardiovascular disease mortality among men with diabetes.

BACKGROUND: Questions remain as to whether higher levels of cardiorespiratory fitness, a measure of regular physical activity, are associated with lower risk of cardiovascular disease (CVD) mortality in overweight and obese individuals with diabetes. Our objective was to quantify the independent and joint relations of cardiorespiratory fitness (hereafter, fitness) and body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) with CVD mortality in men with diabetes. METHODS: This study was conducted using prospective observational data from the Aerobics Center Longitudinal Study. Study participants comprised 2316 men with no history of stroke or myocardial infarction and who were diagnosed as having diabetes (mean [SD] age, 50 [10] years); had a medical examination, including a maximal exercise test during 1970 to 1997 with mortality surveillance to December 31, 1998; and had a BMI of 18.5 or greater and less than 35.0. The main outcome measure was CVD mortality across levels of fitness with stratification by BMI. RESULTS: We identified 179 CVD deaths during a mean (SD) follow-up of 15.9 (7.9) years and 36,710 man-years of exposure. In a model containing age, examination year, fasting glucose level, systolic blood pressure, parental history of premature CVD, total cholesterol level, cigarette smoking, abnormal resting, and exercise electrocardiograms, a significantly higher adjusted risk of mortality was observed in men with a low fitness level who were normal weight (hazard ratio, 2.7 [95% confidence interval, 1.3-5.7]), overweight (hazard ratio, 2.7 [95% confidence interval, 1.4-5.1]), and class 1 obese (hazard ratio, 2.8 [95% confidence interval, 1.4-5.1]) compared with normal weight men with a high fitness level. CONCLUSION: In this cohort of men with diabetes, low fitness level was associated with increased risk of CVD mortality within normal weight, overweight, and class 1 obese weight categories.

Body Mass Index↗
PubMed2005

Coronary artery calcium score and coronary heart disease events in a large cohort of asymptomatic men and women.

Coronary artery calcium (CAC), a measure of subclinical coronary heart disease (CHD), may be useful in identifying asymptomatic persons at risk of CHD events. The current study included 10,746 adults who were 22-96 years of age, were free of known CHD, and had their CAC quantified by electron-beam tomography at baseline as part of a preventive medical examination at the Cooper Clinic (Dallas, Texas) during 1995-2000. During a mean follow-up of 3.5 years, 81 hard events (CHD death, nonfatal myocardial infarction) and 287 total events (hard events plus coronary revascularization) occurred. Age-adjusted rates (per 1,000 person-years) of hard events were computed according to four CAC categories: no detectable CAC and incremental sex-specific thirds of detectable CAC; these rates were, respectively, 0.4, 1.5, 4.8, and 8.7 (trend p<0.0001) for men and 0.7, 2.3, 3.1, and 6.3 (trend p=0.02) for women. CAC levels also were positively associated with rates of total CHD events for women and men (trend p<0.0001 each). The association between CAC and CHD events remained significant after adjustment for CHD risk factors. CAC was associated with CHD events in persons with no baseline CHD risk factors and in younger (aged <40 years) and older (aged >65 years) study participants. These findings show that CAC is associated with an increased risk of CHD events in asymptomatic women and men.

Adult↗
PubMed2005

Cardiorespiratory fitness is inversely associated with the incidence of metabolic syndrome: a prospective study of men and women.

BACKGROUND: Few studies have reported the relationship between cardiorespiratory fitness and metabolic syndrome incidence, particularly in women. METHODS AND RESULTS: We prospectively studied 9007 men (mean+/-SD age, 44+/-9 years; body mass index, 25+/-3 kg/m2) and 1491 women (age, 44+/-9 years; body mass index, 22+/-2 kg/m2) who were free of metabolic syndrome and for whom measures of waist girth, resting blood pressure, fasting lipids, and glucose were taken during baseline and follow-up examinations. Baseline cardiorespiratory fitness was quantified as duration of a maximal treadmill test. Metabolic syndrome was defined with NCEP ATP-III criteria. During a mean follow-up of 5.7 years, 1346 men and 56 women developed metabolic syndrome. Age-adjusted incidence rates were significantly lower (linear trend, P<0.001) across incremental thirds of fitness in men and women. After further adjustment for potential confounders, multivariable hazard ratios for incident metabolic syndrome among men in the low, middle, and upper thirds of fitness, were 1.0 (referent), 0.74 (95% CI, 0.65 to 0.84), and 0.47 (95% CI, 0.40 to 0.54) (linear trend P<0.001); in women, they were 1.0 (referent), 0.80 (95% CI, 0.44 to 1.46), and 0.37 (95% CI, 0.18 to 0.80) (linear trend P=0.01), respectively. Similar patterns of significant inverse associations between fitness and metabolic syndrome incidence were seen when men were stratified on categories of body mass index, age, and number of baseline metabolic risk factors, but patterns were variable in women. CONCLUSIONS: Low cardiorespiratory fitness is a strong and independent predictor of incident metabolic syndrome in women and men. Clinicians should consider the potential benefits of greater cardiorespiratory fitness in the primary prevention of metabolic syndrome, particularly among patients who have already begun to cluster metabolic syndrome components.

Adult↗
PubMed2005

Assessing cardiorespiratory fitness without performing exercise testing.

BACKGROUND: Low cardiorespiratory fitness (CRF) is associated with increased risk of chronic diseases and mortality; however, CRF assessment is usually not performed in many healthcare settings. The purpose of this study is to extend previous work on a non-exercise test model to predict CRF from health indicators that are easily obtained. METHODS: Participants were men and women aged 20 to 70 years whose CRF level was quantified with a maximal or submaximal exercise test as part of the National Aeronautics and Space Administration/Johnson Space Center (NASA, n = 1863), Aerobics Center Longitudinal Study (ACLS, n = 46,190), or Allied Dunbar National Fitness Survey (ADNFS, n = 1706). Other variables included gender, age, body mass index, resting heart rate, and self-reported physical activity levels. RESULTS: All variables used in the multiple linear regression models were independently related to the CRF in each of the study cohorts. The multiple correlation coefficients obtained within NASA, ACLS, and ADNFS participants, respectively, were 0.81, 0.77, and 0.76. The standard error of estimate (SEE) was 1.45, 1.50, and 1.97 metabolic equivalents (METs) (1 MET = 3.5 ml O(2) uptake.kilograms of body mass(-1).minutes(-1)), respectively, for the NASA, ACLS, and ADNFS regression models. All regression models demonstrated a high level of cross-validity (0.72 < R < 0.80). The highest cross-validation coefficients were seen when the NASA regression model was applied to the ACLS and ADNFS cohorts (R = 0.76 and R = 0.75, respectively). CONCLUSIONS: This study suggests that CRF may be accurately estimated in adults from a non-exercise test model including gender, age, body mass index, resting heart rate, and self-reported physical activity.

Adult↗
PubMed2005

An accurate VO2max nonexercise regression model for 18-65-year-old adults.

The purpose of this study was to develop a regression equation to predict maximal oxygen uptake (VO2max) based on nonexercise (N-EX) data. All participants (N = 100), ages 18-65 years, successfully completed a maximal graded exercise test (GXT) to assess VO2max (M = 39.96 mL x kg(-1) x min(-1), SD = 9.54). The N-EX data collected just before the maximal GXT included the participant's age; gender; body mass index (BMI); perceived functional ability (PFA) to walk, jog, or run given distances; and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL x kg(-1) x min(-1), % SEE = 8.62): VO2max (mL x kg(-1) x min(-1)) = 48.0730 + (6.1779 x gender; women = 0, men = 1) - (0. 2463 x age) - (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (R(p) = .91 and SEE(p) = 3.63 mL x kg(-1) x min(-1)); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (ages 18-65 years) with a similar cardiorespiratory fitness level. Based on standardized beta-weights, the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women.

Adolescent↗
PubMed2005

Influence of cardiorespiratory fitness on the association between C-reactive protein and metabolic syndrome prevalence in racially diverse women.

BACKGROUND: Metabolic syndrome and C-reactive protein (CRP) are independent predictors of cardiovascular disease (CVD) among women. The extent to which cardiorespiratory fitness influences the relationship between CRP and metabolic syndrome is unknown. METHODS AND RESULTS: Cross-sectional associations among fitness, CRP, and metabolic syndrome were examined in 135 African American, Native American, and Caucasian women (55 +/- 11 years, 28 +/- 6 kg/m2). Fitness was quantified with a symptom-limited maximal treadmill exercise test. Plasma CRP concentrations were determined with the Dade-Behring high-sensitivity immunoassay. Metabolic syndrome was defined according to NCEP-ATP III. Metabolic syndrome, CRP, and fitness varied (p < 0.05) by race. Race-adjusted CRP values were directly associated (p < 0.05) with each metabolic syndrome component. After adjusting for age and race, the relative odds of metabolic syndrome was 3.6 (95% CI = 1.5 - 8.4) in women with elevated (> 2.0 mg/L) vs. low CRP. Adjustment for smoking, hormone therapy, body mass index (BMI), and HOMA insulin resistance did not eliminate this association (p < 0.05). The association between CRP and the metabolic syndrome was no longer significant (OR = 1.3, 95% CI = 0.9 - 5.9, p = 0.59) after adjustment for fitness. CONCLUSIONS: Higher cardiorespiratory fitness may be an important consideration in the milieu of vascular inflammation and metabolic syndrome.

Adult↗
PubMed2005

Physical activity and diabetes prevention.

Diabetes has reached epidemic proportions worldwide and is associated with a large economic burden, increased risk of cardiovascular disease, and premature mortality. Hyperglycemia is the hallmark clinical manifestation of diabetes and evolves through a multifactorial etiology of genetic, environmental, and behavioral enablers. Approximately 90% of diabetes cases are the non-insulin-dependent phenotype, which is characterized by a progressive deterioration in insulin-mediated glucose disposal, particularly by peripheral tissues. Our hypothesis is that the most proximal behavioral cause of insulin resistance is physical inactivity. Indeed, several streams of scientific research have demonstrated a role for physical activity in the etiology and prevention of diabetes and its related morbidity. In this review we will discuss some of the key observational and experimental studies that have examined associations among physical activity, cardiorespiratory fitness, and non-insulin-dependent diabetes.

Clinical Trials as Topic↗
PubMed2005

The diabetes prevention program: a worksite experience.

The purpose of this study was to determine if the U.S. National Institutes of Health Diabetes Prevention Program (DPP) could be successfully implemented in a worksite setting. Thirty-seven adult employees of BD Medical Systems of Sandy, Utah were enrolled in a single-group time-series study using the DPP. Two-hour oral glucose tolerance tests (OGTT) and other outcomes were measured at baseline, 6 months, and 12 months. Weight, body mass index, waist circumference, 2-hour OGTT, very low density lipoproteins, triglycerides, and aerobic fitness were significantly improved at 6 and 12 months and showed overall significant improvement across time. Fasting blood insulin, total cholesterol, low density lipoproteins, and total cholesterol/high density lipoproteins ratio were significantly improved at 6 months, but not at 12 months. Eighteen of the program participants (51%) were no longer in the pre-diabetes and diabetes categories after 1 year. Existing worksite health promotion and occupational health professionals can successfully offer the DPP and help employees improve glucose tolerance.

Analysis of Variance↗