Biomedical subjects

Edward P Weiss

Publications and source records attributed to Edward P Weiss.

14 recordsLinked to original sources

PubMed2007

FABP2 Ala54Thr genotype is associated with glucoregulatory function and lipid oxidation after a high-fat meal in sedentary nondiabetic men and women.

BACKGROUND: A common functional missense mutation [Ala54Thr of the fatty acid-binding protein 2 gene (FABP2)] has previously been studied for associations with glucoregulation, postprandial lipemia, and lipid oxidation rates. However, most of those studies have not accounted for the interactive and potentially confounding effects of habitual physical activity and diet. OBJECTIVE: We tested the hypothesis that, in sedentary nondiabetic subjects following a low-fat diet, Thr54 FABP2 carriers have lower glucoregulatory function, greater postprandial lipemia, and greater lipid oxidation rates than do their Ala54 FABP2-homozygous counterparts. DESIGN: Men and women (n = 122) aged 50-75 y who were following a low-fat diet were genotyped and underwent oral-glucose-tolerance tests. A subgroup (n = 36) also underwent postprandial lipemia tests with lipid oxidation rate measurements. RESULTS: Thr54 carriers were less likely to have normal glucose tolerance (P = 0.05) and had higher fasting glucose concentrations (P = 0.003) than did Ala54 homozygotes. In Thr54 carriers, the insulin sensitivity index was lower (P = 0.02), and the fasting insulin and the oral-glucose-tolerance test insulin area under the curve were higher (P = 0.05 and 0.03, respectively) than in Ala54 homozygotes. FABP2 genotype was not associated with fasting or postprandial lipemia test triacylglycerol or free fatty acids (P > or = 0.22 for all), but postprandial lipid oxidation rates were higher (P = 0.01), which suggests that fat absorption is higher in Thr54 carriers than in Ala54 homozygotes. CONCLUSIONS: In sedentary nondiabetic persons following a low-fat diet, FABP2 Thr54 carriers have lower glucose tolerance and lower insulin action than do Ala54-homozygous persons. Furthermore, FABP Thr54 carriers have higher lipid oxidation rates, which may be the mechanism of glucoregulatory dysfunction.

Aged↗

PubMed2006

Lower extremity muscle size and strength and aerobic capacity decrease with caloric restriction but not with exercise-induced weight loss.

Caloric restriction (CR) results in fat loss; however, it may also result in loss of muscle and thereby reduce strength and aerobic capacity (VO2 max). These effects may not occur with exercise-induced weight loss (EX) because of the anabolic effects of exercise on heart and skeletal muscle. We tested the hypothesis that CR reduces muscle size and strength and VO2 max, whereas EX preserves or improves these parameters. Healthy 50- to 60-yr-old men and women (body mass index of 23.5-29.9 kg/m2) were studied before and after 12 mo of weight loss by CR (n = 18) or EX (n = 16). Lean mass was assessed by dual-energy X-ray absorptiometry, thigh muscle volume by MRI, isometric and isokinetic knee flexor strength by dynamometry, and treadmill VO2 max by indirect calorimetry. Both interventions caused significant decreases in body weight (CR: -10.7 +/- 1.4%, EX: -9.5 +/- 1.5%) and lean mass (CR: -3.5 +/- 0.7%, EX: -2.2 +/- 0.8%), with no significant differences between groups. Significant decreases in thigh muscle volume (-6.9 +/- 0.8%) and composite knee flexion strength (-7.2 +/- 3%) occurred in the CR group only. Absolute VO2 max decreased significantly in the CR group (-6.8 +/- 2.3%), whereas the EX group had significant increases in both absolute (+15.5 +/- 2.4%) and relative (+28.3 +/- 3.0%) VO2 max. These data provide evidence that muscle mass and absolute physical work capacity decrease in response to 12 mo of CR but not in response to a similar weight loss induced by exercise. These findings suggest that, during EX, the body adapts to maintain or even enhance physical performance capacity.

Adaptation, Physiological↗

PubMed2006

Hemostatic response to postprandial lipemia before and after exercise training.

Chronic hypertriglyceridemia is thought to be atherogenic and is associated with an elevated thrombotic potential, both of which may be improved with aerobic exercise training. Eight subjects were tested for aerobic capacity, body composition, and postprandial lipemia (PPL), followed by 6 mo of exercise training and final testing. Blood samples were obtained for measurement of free fatty acid (FFA), triglycerides (TG), insulin (Ins), and glucose (Glu). Hemostatic variables including factor VII activity (FVIIa), tissue factor pathway inhibitor-factor Xa complex (TFPI/Xa), and plasminogen activator inhibitor-1 (PAI-1) antigen/activity as well as leukocyte tumor necrosis factor-alpha (TNF-alpha) gene expression were determined among four subjects. We found that the exercise training was of sufficient intensity to increase aerobic capacity (P < 0.0001) and improve body composition (P = 0.04). There were no differences between tests among PPL responses of FFA, TG, Ins, or Glu; however, the mean TG response and fat oxidation rate improved. PAI-1 antigen/activity, FVIIa, TFPI/Xa, and TNF-alpha gene expression were all improved after exercise training after adjusting for confounders. We conclude that aerobic exercise training reduces the potential for coagulation, improves fibrinolytic potential, and reduces leukocyte TNF-alpha gene expression after the ingestion of a high-fat meal.

Aged↗

PubMed2006

Gender differences in the decline in aerobic capacity and its physiological determinants during the later decades of life.

We investigated the hemodynamic determinants of the age-associated decline in maximal oxygen uptake (V(O2 max)) and the influence of gender on the decline in V(O2 max) and its determinants in old and very old men and women. Sedentary, 60- to 92-yr-old women (n = 71) and men (n = 29), with no evidence of cardiovascular disease, underwent maximal treadmill exercise tests during which V(O2 max) and maximal cardiac output (Q(max)) were determined. V(O2 max) and age were inversely related in both women (-23 +/- 2 ml.min(-1).yr(-1); P < 0.0001) and men (-57 +/- 5 ml.min(-1).yr(-1); P < 0.0001). The absolute slope of the V(O2 max) vs. age relationship was twofold steeper in men than in women (P < 0.0001). Q(max) was also inversely related to age in a gender-specific manner (women = -87 +/- 25 ml.min(-1).yr(-1), P = 0.0009; men = -215 +/- 50 ml.min(-1).yr(-1), P = 0.0002; P = 0.01 women vs. men). Age-related changes in maximal exercise arteriovenous oxygen content difference (a-vD(O2)) were marginally different (P = 0.08) between women (-0.12 +/- 0.03 ml.dl(-1).yr(-1), P = 0.0003) and men (-0.22 +/- 0.04 ml.dl(-1).yr(-1), P < 0.0001). Age-associated decreases in Q(max) and a-vD(O2) contributed equally to the declines in V(O2 max) in both men and women. In the later stages of life, V(O2 max), Q(max), and a-vD(O2) decrease with age more rapidly in older men than they do in older women. As a result, the gender differences dissipate in the later decades of life. Declines in Q(max) and a-vD(O2) contribute equally to the age-related decrease in V(O2 max) in men and women.

Adaptation, Physiological↗

PubMed2006

Improvements in glucose tolerance and insulin action induced by increasing energy expenditure or decreasing energy intake: a randomized controlled trial.

BACKGROUND: Weight loss, through calorie restriction or increases in energy expenditure via exercise, improves glucose tolerance and insulin action. However, exercise-induced energy expenditure may further improve glucoregulation through mechanisms independent of weight loss. OBJECTIVE: The objective was to assess the hypothesis that weight loss through exercise-induced energy expenditure improves glucoregulation and circulating factors involved in insulin action to a greater extent than does similar weight loss through calorie restriction. DESIGN: Sedentary men and women aged 50-60 y with a body mass index (kg/m(2)) of 23.5-29.9 were randomly assigned to 1 of 2 weight-loss interventions [12 mo of exercise training (EX group; n = 18) or calorie restriction (CR group; n = 18)] or to a healthy lifestyle (HL) control group (n = 10). The insulin sensitivity index and areas under the curve for glucose and insulin were assessed with an oral-glucose-tolerance test. Adiponectin and tumor necrosis factor alpha concentrations were measured in fasting serum. Fat mass was measured by dual-energy X-ray absorptiometry. RESULTS: Yearlong energy deficits were not significantly different between the EX and CR groups, as evidenced by body weight and fat mass changes. The insulin sensitivity index increased and the glucose and insulin areas under the curve decreased in the EX and CR groups, remained unchanged in the HL group, and did not differ significantly between the EX and CR groups. Marginally significant increases in adiponectin and decreases in the ratio of tumor necrosis factor alpha to adiponectin occurred in the EX and CR groups but not in the HL group. CONCLUSIONS: Weight loss induced by exercise training or calorie restriction improves glucose tolerance and insulin action in nonobese, healthy, middle-aged men and women. However, it does not appear that exercise training-induced weight loss results in greater improvements than those that result from calorie restriction alone.

Adiponectin↗

PubMed2006

One year of caloric restriction in humans: feasibility and effects on body composition and abdominal adipose tissue.

BACKGROUND: Caloric restriction (CR) increases maximal life span in short-lived organisms, and its effects are being explored in nonhuman primates. The objectives of this study were to determine the feasibility of prolonged CR in nonobese adults and to compare the effects of CR- and exercise-induced weight loss on body composition and abdominal adiposity. METHODS: A randomized, controlled trial was conducted with 48 healthy, nonobese women and men, aged 57 +/- 1 (mean +/- standard error [SE]) years, with body mass index 27.3 +/- 0.3 kg/m2. Participants were randomly assigned to a 20% calorically-restricted diet (CR, n = 19), exercise designed to produce a similar energy deficit (EX, n = 19), or a healthy lifestyle control group (HL, n = 10) for 1 year. Assessments included weight, body composition by dual-energy x-ray absorptiometry, abdominal adipose tissue by magnetic resonance imaging, and energy intake by doubly labeled water. RESULTS: The average level of CR achieved by the CR group was 11.5 +/- 2.1%, and the EX group completed 59 +/- 6.7% of their prescribed exercise. Weight changes were greater (p <or=.0005) in the CR (-8.0 +/- 0.9 kg) and EX (-6.4 +/- 0.9) groups as compared to the HL group (-1.3 +/- 0.9 kg), corresponding to reductions of 10.7%, 8.4%, and 1.7% of baseline weights, respectively. Whole-body fat mass and visceral and subcutaneous abdominal adipose tissue decreased significantly (p <.005) and comparably in the CR and EX groups, but did not change in the HL group. CONCLUSIONS: CR for 1 year was feasible, but the level of CR achieved was less than prescribed. CR and exercise were equally effective in reducing weight and adiposity.

Abdominal Fat↗

PubMed2006

Abdominal adiposity is a stronger predictor of insulin resistance than fitness among 50-95 year olds.

OBJECTIVE: Physical inactivity and increased adiposity contribute to insulin resistance; less is known, however, about the relative contributions of these factors in older adults. The aim of this study was to determine whether cardiovascular fitness, whole-body adiposity, or abdominal adiposity is the strongest predictor of insulin resistance into old age. RESEARCH DESIGN AND METHODS: Subjects included 407 men and women aged 50-95 years (means +/- SD 69 +/- 11 years). Insulin resistance was estimated using the insulin sensitivity index (ISI) of Matsuda and DeFronzo [ISI = 10,000/square root of (fasting glucose x fasting insulin) x (mean glucose x mean insulin during an oral glucose tolerance test); lower ISI = greater insulin resistance]. Fitness was determined with a treadmill maximal oxygen consumption (Vo(2max)) test. Whole-body adiposity measures included BMI and percent fat by dual-energy X-ray absorptiometry or hydrodensitometry; abdominal adiposity was estimated by waist circumference. RESULTS: Waist circumference was the strongest independent correlate of ISI (r = -0.52, P < 0.0001), explaining 28% of the variance when controlling for sex, BMI, percent fat, and Vo(2max). BMI (r = -0.45), percent fat (r = -0.40), and Vo(2max) (r = 0.22) independently predicted ISI (all P < 0.0001); however, after controlling for waist circumference, only Vo(2max) remained significant (r = 0.13, P = 0.009). CONCLUSIONS: Adiposity and fitness continue to be significant predictors of insulin sensitivity into old age, with abdominal obesity being the most important single factor. These findings support the measurement of waist circumference to assess health risk among older adults.

Abdominal Fat↗

PubMed2005

Endurance training-induced changes in the insulin response to oral glucose are associated with the peroxisome proliferator-activated receptor-gamma2 Pro12Ala genotype in men but not in women.

The present study sought to investigate, in sedentary men and women, (a) whether a common functional gene variant (peroxisome proliferator-activated receptor-gamma2 [PPARgamma2] Pro12Ala) predicts insulin action and (b) whether improvements in insulin action in response to endurance exercise training are associated with PPARgamma2 Pro12Ala. Sedentary, 50- to 75-year-old men and women (N = 73) were genotyped and underwent oral glucose tolerance tests (OGTTs) before and after 6 months of endurance training. At baseline, men heterozygous for the Pro12Ala variant had a greater OGTT insulin area under the curve (AUC) as compared with Pro12 homozygous men (P = .009). Endurance training resulted in a significantly greater improvement in insulin AUC in Pro12Ala heterozygous men as compared with Pro12 homozygous men (P = .003) despite no genotype-specific differences with respect to training-induced changes in body weight, body mass index, and percent body fat. No differences between genotype groups were present at baseline or in response to training in women. Training did not alter the OGTT glucose AUC for the group as a whole, and the baseline, final, and change in glucose AUC were not dependent on PPARgamma2 genotype and/or sex. In conclusion, these findings suggest that sedentary men with the PPARgamma2 Pro12Ala variant have lower insulin action on glucose disposal as compared with their counterparts. However, these men are particularly responsive with respect to the magnitude of endurance training-induced improvement in insulin action.

Aged↗

PubMed2005

Modest weight loss improves insulin action in obese African Americans.

OBJECTIVE: We have previously shown that short-term energy restriction followed by modest lifestyle changes improves glucose tolerance for up to 1 year in obese individuals. The purpose of the present study was to determine the mechanism by which improvements in glucose tolerance occur in obese African Americans with insulin resistance and abnormal glucose tolerance. RESEARCH DESIGN AND METHODS: Nine subjects (53 +/- 2 years; body mass index, 37 +/- 3 kg/m 2 [mean +/- SEM]) received a low-energy diet (3883 +/- 222 kJ/d) for 1 week, and then followed a modest lifestyle intervention program for up to 1 year. Body composition was estimated by hydrostatic weighing, and insulin secretion and action were assessed during a hyperglycemic clamp with superimposed arginine infusion and fat meal. Baseline and final tests were performed during weight stability. RESULTS: Significant improvements ( P < .05) were observed for body weight (-6.1 +/- 1.1 kg), body composition (-5.5 +/- 1.3 kg fat mass), fasting plasma glucose (-1.1 +/- 0.3 mmol/L), fasting insulin (-52 +/- 21 pmol/L), oral glucose tolerance, and insulin action (+24%), defined as an increase in glucose disposal rate relative to plasma insulin concentration during the hyperglycemic clamp. These improvements were independent of an acute effect of energy restriction or weight loss, because body weight was stable. CONCLUSIONS: These results suggest that the improvements in glucose tolerance with a modest lifestyle intervention were attributable to an improvement in insulin action, and provide evidence that despite persistent obesity (body mass index, 34.7 +/- 2.4 kg/m 2 ), long-term benefits can be achieved with relatively small weight loss in obese African Americans.

Black People↗

PubMed2004

Influence of the interleukin-6 -174 G/C gene polymorphism on exercise training-induced changes in glucose tolerance indexes.

A polymorphism in the IL-6 gene, a G-to-C substitution 176 bp upstream of the ATG translation initiation site, has been associated with diabetes prevalence and insulin resistance. Interventions including exercise training are frequently used to modify cardiovascular disease risk factors. Consequently, this project examined associations between the IL-6 -174 genotype and oral glucose tolerance test outcomes in 50- to 75-yr-old sedentary men and postmenopausal women before and after aerobic exercise training. Among the 87 individuals who started the study, 56 were retested after 6 mo of aerobic exercise training. Subject characteristics at baseline did not differ between the IL-6 genotype groups with the exception of fasting glucose, which was higher (P = 0.02, covariates age, gender, and ethnicity) in the CC genotype group. The training-induced change in glucose area under the curve during the oral glucose tolerance test varied between the IL-6 -174 genotype groups (P = 0.05, covariates age, gender, ethnicity, baseline glucose area under the curve, and percent body fat change) with a significant decrease occurring only in the GG genotype group. Insulin outcomes did not differ among the groups at baseline or after training. Training-induced changes in weight, percent body fat, maximal oxygen consumption, fasting glucose, and an insulin sensitivity index also changed similarly among the genotype groups. In conclusion, fasting glucose and the extent to which glucose tolerance changes with exercise training may be influenced by the IL-6 -174 gene polymorphism.

Age Factors↗

PubMed2004

Plasma nitrate/nitrite response to an oral glucose load and the effect of endurance training.

To assess the role of circulating nitric oxide (NO) production in glucose homeostasis, plasma nitrate/nitrite (NO(x)) was assessed during oral glucose tolerance tests (OGTTs) on 64 sedentary subjects and in a subset 40 subjects before and after 6 months of endurance exercise training. NO(x) decreased with the oral glucose load (P </=.001 for linear and quadratic effects). OGTT NO(x) response indices (NO(x) response area (NO(x) AREA), change in NO(x) from baseline to the minimum (DeltaNO(x)), and NO(x) time-to-minimum) were not associated with OGTT insulin or glucose areas under the curve (AUCs) or with insulin sensitivity index (ISI). Training did not alter NO(x) AREA, or DeltaNO(x), however, NO(x) time-to-minimum occurred later after training (P =.038). Training-induced insulin AUC and ISI changes were not associated with OGTT NO(x) index changes; however, glucose total AUC changes were associated with changes in NO(x) AREA (r =.42, P =.007) and DeltaNO(x) (r =.37, P =.019). In conclusion, these data suggest that circulating NO production is not involved in glycemic control after an oral glucose load in sedentary adults. In response to endurance training, however, it appears that the time required to reach minimum NO(x) levels after a glucose load is greater after training. Furthermore, although the magnitude of NO(x) response (as indicated by NO(x) AREA and DeltaNO(x)) to an oral glucose load does not appear to change with training for all individuals, individual training-induced changes in the NO(x) response magnitude are partly explained by training-induced changes in OGTT glucose responses.

Administration, Oral↗

PubMed2002

Fatty acid binding protein-2 gene variants and insulin resistance: gene and gene-environment interaction effects.

The intestinal fatty acid binding protein (FABP2) gene is proposed as a candidate gene for diabetes because the protein it codes is involved in fatty acid (FA) absorption and metabolism and may, therefore, affect insulin sensitivity and glucose metabolism. Numerous studies have assessed FABP2 gene variants and their association with insulin resistance and type 2 diabetes. Some weak evidence indicates that the silent variants and those in the noncoding regions of the gene (codon 118, 3' noncoding region, intron 2 trinucleotide repeat) might be associated with insulin resistance/type 2 diabetes. The most extensively studied variant is the missense Ala54Thr variation, which is common in diverse populations and results in increased FA absorption in vivo. Some evidence indicates that this variant may be associated with insulin sensitivity/type 2 diabetes. However, the large majority of studies assessing the potential association between the Ala54Thr FABP2 variant and insulin resistance/type 2 diabetes did not account for the independent and substantial effects of body composition, habitual physical activity (PA) levels, and diet on insulin resistance. We recently reported that there was an association between Ala54Thr FABP2 genotypes and insulin sensitivity after accounting for the independent effects of body composition and habitual PA levels on insulin sensitivity. Furthermore, others have demonstrated that Ala54Thr FABP2 may associate with insulin sensitivity, but only if individuals are consuming a high-fat diet. These results highlight the importance of including behavioral and environmental factors in the design of studies seeking to assess the impact of genes on physiological and clinical outcome phenotypes.

Amino Acid Substitution↗

PubMed2002

The relationship of age and cardiovascular fitness to cognitive and motor processes.

Older and younger aerobically trained and sedentary adults participated in an S1-S2-S3 paradigm designed to elicit event-related potential (ERP) and behavioral responses to determine the influence of cardiovascular fitness on cognitive and motor processes. The paradigm provided warning (S1) as to the difficulty level of an upcoming decision task (S2). Participants had to decide the taller of two bars on presentation of S2 but hold their response until S3, to which they indicated their choice motorically. Results revealed age-related differences for ERP measures as older participants showed increased amplitude of the stimulus preceding negativity (SPN) prior to S2, and longer latencies and equipotentiality of P3 in response to S2. Fitness effects were also observed for the contingent negative variation (CNV) with decreased amplitude for fit relative to sedentary individuals. Age interacted with fitness for P3 latency to S2 as older sedentary individuals showed the longest latency followed by older fit and both younger groups. No significant group differences were observed for reaction time (RT) to S3. Therefore, physical fitness is associated with attenuation of cognitive decline in older individuals and greater economy of motor preparation for both young and older participants.

Adolescent↗

PubMedDate not supplied

Bone mineral density response to caloric restriction-induced weight loss or exercise-induced weight loss: a randomized controlled trial.

BACKGROUND: Bone loss often accompanies weight loss induced by caloric restriction (CR), but whether bone loss accompanies similar weight loss induced by exercise (EX) is unknown. We tested the hypothesis that EX-induced weight loss is associated with less bone loss compared with CR-induced weight loss. METHODS: Forty-eight adults (30 women; 18 men; mean +/- SD age, 57 +/- 3 years; and mean +/- SD body mass index, 27 +/- 2 kg/m2) were randomized to 1 of 3 groups for 1 year: CR group (n = 19), regular EX group (n = 19), or a healthy lifestyle (HL) control group (n = 10). Primary outcome measure was change in hip and spine bone mineral density (BMD). Secondary outcomes were bone markers and hormones. RESULTS: Body weight decreased similarly in the CR and EX groups (10.7% +/- 6.3% [-8.2 +/- 4.8 kg] vs 8.4% +/- 6.3% [-6.7 +/- 5.6 kg]; P = .21), whereas weight did not change in the HL group (-1.2% +/- 2.5% [-0.9 +/- 2.0 kg]). Compared with the HL group, the CR group had decreases in BMD at the total hip (-2.2% +/- 3.1% vs 1.2% +/- 2.1%; P = .02) and intertrochanter (-2.1% +/- 3.4% vs 1.7 +/- 2.8%; P = .03). The CR group had a decrease in spine BMD (-2.2% +/- 3.3%; P = .009). Despite weight loss, the EX group did not demonstrate a decrease in BMD at any site. Body weight changes correlated with BMD changes in the CR (R = 0.61; P = .007) but not in the EX group. Bone turnover increased in both CR and EX groups. CONCLUSIONS: CR-induced weight loss, but not EX-induced weight loss, is associated with reductions in BMD at clinically important sites of fracture. These data suggest that EX should be an important component of a weight loss program to offset adverse effects of CR on bone.

Alkaline Phosphatase↗