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1.
Lipids ; 53(5): 547-558, 2018 05.
Article in English | MEDLINE | ID: mdl-30074625

ABSTRACT

The rate at which dietary α-linolenic acid (ALA) is desaturated and elongated to its longer-chain n-3 polyunsaturated fatty acid (PUFA) in humans is not agreed upon. In this study, we applied a methodology developed using rodents to investigate the whole-body, presumably hepatic, synthesis-secretion rates of esterified n-3 PUFA from circulating unesterified ALA in 2 healthy overweight women after 10 weeks of low-linoleate diet exposure. During continuous iv infusion of d5-ALA, 17 arterial blood samples were collected from each subject at -10, 0, 10, 20, 40, 60, 80, 100, 120, 150, 180, and 210 min, and at 4, 5, 6, 7, and 8 h after beginning infusion. Plasma esterified d5-n-3 PUFA concentrations were plotted against the infusion time and fit to a sigmoidal curve using nonlinear regression. These curves were used to estimate kinetic parameters using a kinetic analysis developed using rodents. Calculated synthesis-secretion rates of esterified eicosapentaenoate, n-3 docosapentaenoate, docosahexaenoic acid, tetracosapentaenate, and tetracosahexaenoate from circulating unesterified ALA were 2.1 and 2.7; 1.7 and 5.3; 0.47 and 0.27; 0.30 and 0.30; and 0.32 and 0.27 mg/day for subjects S01 and S02, respectively. This study provides new estimates of whole-body synthesis-secretion rates of esterified longer-chain n-3 PUFA from circulating unesterified ALA in human subjects. This method now can be extended to study factors that regulate human whole-body PUFA synthesis-secretion in health and disease.


Subject(s)
Docosahexaenoic Acids/blood , Eicosapentaenoic Acid/blood , alpha-Linolenic Acid/blood , Adolescent , Adult , Body Mass Index , Female , Healthy Volunteers , Humans , Middle Aged , Young Adult
2.
Cell Metab ; 22(3): 427-36, 2015 Sep 01.
Article in English | MEDLINE | ID: mdl-26278052

ABSTRACT

Dietary carbohydrate restriction has been purported to cause endocrine adaptations that promote body fat loss more than dietary fat restriction. We selectively restricted dietary carbohydrate versus fat for 6 days following a 5-day baseline diet in 19 adults with obesity confined to a metabolic ward where they exercised daily. Subjects received both isocaloric diets in random order during each of two inpatient stays. Body fat loss was calculated as the difference between daily fat intake and net fat oxidation measured while residing in a metabolic chamber. Whereas carbohydrate restriction led to sustained increases in fat oxidation and loss of 53 ± 6 g/day of body fat, fat oxidation was unchanged by fat restriction, leading to 89 ± 6 g/day of fat loss, and was significantly greater than carbohydrate restriction (p = 0.002). Mathematical model simulations agreed with these data, but predicted that the body acts to minimize body fat differences with prolonged isocaloric diets varying in carbohydrate and fat.


Subject(s)
Diet, Carbohydrate-Restricted , Diet, Fat-Restricted , Diet, Reducing , Obesity/diet therapy , Adipose Tissue/metabolism , Adipose Tissue/pathology , Adult , Dietary Carbohydrates/metabolism , Dietary Fats/metabolism , Energy Intake , Female , Humans , Male , Models, Biological , Obesity/metabolism , Obesity/pathology , Oxidation-Reduction
3.
Article in English | MEDLINE | ID: mdl-25110634

ABSTRACT

OBJECTIVE: Weight loss interventions have produced little change in insulin sensitivity in black women, but mean data may obscure metabolic benefit to some and adverse effects for others. Accordingly, we analyzed insulin sensitivity relative to fat mass change following a weight loss program. DESIGN AND METHODS: Fifty-four black women (BMI range 25.9 to 54.7 kg/m2) completed the 6-month program that included nutrition information and worksite exercise facilities. Fat mass was measured by dual-energy X-ray absorptiometry, and insulin sensitivity index (SI) was calculated from an insulin-modified intravenous glucose tolerance test using the minimal model. RESULTS: Baseline SI (range 0.74 to 7.58 l/mU-1•min-1) was inversely associated with fat mass (r = -0.516, p < 0.001), independent of age. On average, subjects lost fat mass (baseline 40.8 ± 12.4 to 39.4 ± 12.6 kg [mean ± SD], P < 0.01), but 17 women (32 %) actually gained fat mass. SI for the group was unchanged (baseline 3.3 ± 1.7 to 3.2 ± 1.6, P = 0.67). However, the tertile with greatest fat mass loss (-3.6 kg, range -10.7 to -1.7 kg) improved insulin sensitivity (SI +0.3 ± 1.2), whereas the tertile with net fat mass gain (+0.9 kg, range -0.1 to +3.8 kg) had reduced insulin sensitivity (SI -0.7 ± 1.3) from baseline values (P < 0.05 by ANOVA). CONCLUSIONS: Black women in a weight loss program who lose fat mass may have improved insulin sensitivity, but fat mass gain with diminished sensitivity is common. Additional support for participants who fail to achieve fat mass loss early in an intervention may be required for success.

4.
Nat Neurosci ; 16(11): 1551-2, 2013 Nov.
Article in English | MEDLINE | ID: mdl-24077565

ABSTRACT

Prevailing theories hold that the insula is functionally organized along its caudal-to-rostral axis, with posterior regions coding lower-level sensory information and anterior regions coding higher-level stimulus significance relative to the body's homeostatic needs. Contrary to predictions of this model, the response of the taste-sensitive region of the caudal, but not rostral, insula to food images was directly related to the body's homeostatic state as indexed by levels of peripheral glucose.


Subject(s)
Afferent Pathways/physiology , Brain Mapping , Cerebral Cortex/physiology , Homeostasis/physiology , Taste/physiology , Adult , Afferent Pathways/blood supply , Blood Glucose/physiology , Cerebral Cortex/blood supply , Female , Humans , Image Processing, Computer-Assisted , Magnetic Resonance Imaging , Male , Oxygen , Photic Stimulation , Young Adult
5.
Obesity (Silver Spring) ; 21(9): 1836-42, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23418014

ABSTRACT

OBJECTIVE: Obesity, insulin resistance, and diabetes disproportionately affect African-American (AA) women. Abnormal adipose tissue free fatty acid (FFA) release is associated with these conditions. Resting energy expenditure (REE) and sex predict FFA release in Caucasians, but whether this is true in AA is unknown. The sex-specific relationships between FFA release, REE, and race was compared. DESIGN AND METHODS: 100 adults (47% AA, 50% male, age 32 ± 8 years [mean ± SD]) from three different centers underwent duplicate measures of FFA release ([U-13C] palmitate) and REE (indirect calorimetry). Body composition was determined by DXA and abdominal imaging. RESULTS: AA participants had lower REE, but similar FFA concentrations and flux compared with Caucasian participants. The significant predictors of palmitate release were REE, sex, and race. REE and FFA flux were correlated in both sexes and both races. In a multiple linear regression analysis with palmitate flux as the dependent variable and REE, sex, race, total fat mass, fat-free mass, and insulin as independent variables, REE was the only independent predictor of FFA release in men. Both REE and race predicted palmitate flux in women. CONCLUSIONS: FFA flux is related to REE, but the relationship differs in AA and Caucasian women.


Subject(s)
Basal Metabolism , Black or African American , Fatty Acids, Nonesterified/metabolism , Obesity/metabolism , Palmitic Acid/metabolism , White People , Adult , Calorimetry, Indirect , Female , Humans , Linear Models , Male , Obesity/ethnology , Sex Factors , Young Adult
6.
J Lipid Res ; 53(12): 2767-72, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23048205

ABSTRACT

Type 2 diabetes mellitus (T2DM) is associated with increased plasma triglyceride (TG) concentrations, but African Americans (AA) have lower plasma TG than Caucasians (CC). We evaluated the hypothesis that obese AA women have lower plasma TG than obese CC women do because of differences in lipid kinetics. Eleven AA and 11 CC obese women with T2DM, matched on body mass index (BMI) (AA = 37 ± 1, CC = 37 ± 1 kg/m(2)), age, duration of diabetes, percentage body fat, and insulin sensitivity (S(I), determined by an intravenous glucose tolerance test), were studied. Plasma TG concentration (AA = 1.14 ± 0.11, CC = 1.88 ± 0.18 mmol/l), FFA rate of appearance (R(a)) into plasma (AA = 419 ± 27, CC = 503 ± 31 µmol·min(-1)), and total VLDL-TG secretion rate (AA = 18 ± 2, CC = 29 ± 4 µmol·min(-1)) were lower in AA than CC women (all P < 0.05). In contrast, plasma total apolipoprotein (apo)B-100 concentration (AA = 1,542 ± 179, CC = 1,620 ± 118 nmol/l) and VLDL-apoB-100 secretion rate (AA = 1.3 ± 0.1, CC = 1.3 ± 0.1 nmol·min(-1)) were similar in both groups, so the molar ratio of VLDL-TG secretion rate to VLDL-apoB-100 secretion rate was lower in AA women than in CC women. VLDL-TG concentration was lower in AA women due to lower total VLDL-TG secretion rate. However, the VLDL-apoB-100 secretion rate was the same in both groups, demonstrating that AA women secrete smaller VLDL particles containing less TG than do CC women.


Subject(s)
Black or African American , Diabetes Mellitus, Type 2/metabolism , Fatty Acids/metabolism , Lipoproteins, LDL/metabolism , Obesity/metabolism , White People , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/epidemiology , Fatty Acids/blood , Female , Humans , Kinetics , Lipoproteins, LDL/blood , Middle Aged , Obesity/blood , Obesity/epidemiology
7.
Clin J Am Soc Nephrol ; 7(7): 1103-11, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22653255

ABSTRACT

BACKGROUND AND OBJECTIVES: Concerns exist about deleterious renal effects of low-carbohydrate high-protein weight loss diets. This issue was addressed in a secondary analysis of a parallel randomized, controlled long-term trial. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Between 2003 and 2007, 307 obese adults without serious medical illnesses at three United States academic centers were randomly assigned to a low-carbohydrate high-protein or a low-fat weight-loss diet for 24 months. Main outcomes included renal filtration (GFR) indices (serum creatinine, cystatin C, creatinine clearance); 24-hour urinary volume; albumin; calcium excretion; and serum solutes at 3, 12, and 24 months. RESULTS: Compared with the low-fat diet, low-carbohydrate high-protein consumption was associated with minor reductions in serum creatinine (relative difference, -4.2%) and cystatin C (-8.4%) at 3 months and relative increases in creatinine clearance at 3 (15.8 ml/min) and 12 (20.8 ml/min) months; serum urea at 3 (14.4%), 12 (9.0%), and 24 (8.2%) months; and 24-hour urinary volume at 12 (438 ml) and 24 (268 ml) months. Urinary calcium excretion increased at 3 (36.1%) and 12 (35.7%) months without changes in bone density or clinical presentations of new kidney stones. CONCLUSIONS: In healthy obese individuals, a low-carbohydrate high-protein weight-loss diet over 2 years was not associated with noticeably harmful effects on GFR, albuminuria, or fluid and electrolyte balance compared with a low-fat diet. Further follow-up is needed to determine even longer-term effects on kidney function.


Subject(s)
Diet, Carbohydrate-Restricted , Diet, Fat-Restricted , Dietary Proteins/administration & dosage , Kidney/physiology , Obesity/diet therapy , Adult , Female , Humans , Kidney Function Tests , Male , Middle Aged
8.
Biophys J ; 102(3): 399-406, 2012 Feb 08.
Article in English | MEDLINE | ID: mdl-22325261

ABSTRACT

Inference of the insulin secretion rate (ISR) from C-peptide measurements as a quantification of pancreatic ß-cell function is clinically important in diseases related to reduced insulin sensitivity and insulin action. ISR derived from C-peptide concentration is an example of nonparametric Bayesian model selection where a proposed ISR time-course is considered to be a "model". An inferred value of inaccessible continuous variables from discrete observable data is often problematic in biology and medicine, because it is a priori unclear how robust the inference is to the deletion of data points, and a closely related question, how much smoothness or continuity the data actually support. Predictions weighted by the posterior distribution can be cast as functional integrals as used in statistical field theory. Functional integrals are generally difficult to evaluate, especially for nonanalytic constraints such as positivity of the estimated parameters. We propose a computationally tractable method that uses the exact solution of an associated likelihood function as a prior probability distribution for a Markov-chain Monte Carlo evaluation of the posterior for the full model. As a concrete application of our method, we calculate the ISR from actual clinical C-peptide measurements in human subjects with varying degrees of insulin sensitivity. Our method demonstrates the feasibility of functional integral Bayesian model selection as a practical method for such data-driven inference, allowing the data to determine the smoothing timescale and the width of the prior probability distribution on the space of models. In particular, our model comparison method determines the discrete time-step for interpolation of the unobservable continuous variable that is supported by the data. Attempts to go to finer discrete time-steps lead to less likely models.


Subject(s)
C-Peptide/metabolism , Insulin-Secreting Cells/metabolism , Insulin/metabolism , Models, Biological , Bayes Theorem , Female , Humans , Insulin Secretion , Kinetics , Male , Markov Chains , Monte Carlo Method
9.
Obesity (Silver Spring) ; 20(6): 1218-22, 2012 Jun.
Article in English | MEDLINE | ID: mdl-21760633

ABSTRACT

Randomized controlled trials (RCTs) are considered the gold standard used to assess the efficacy of treatment. While a well implemented RCT can produce an unbiased estimate of the relative difference between treatment groups, the generalizability of these findings may be limited. Specific threats to the external validity include treatment preference. The purposes of this study were to: (i) assess whether receiving one's treatment preference was associated with weight loss and retention and (ii) whether receiving one's treatment preference modified the relationship between the treatments and weight loss. Treatment preference was assessed in 250 subjects prior to but independent of randomization into either low-carbohydrate or low-fat diets. Treatment preference was a predictor of weight loss (P = 0.002) but not retention (P = 0.90). Participants who received their preference lost less weight (-7.7 kg, 95% confidence interval (CI): -9.3 to -6.1) than participants who did not receive their preference (-9.7 kg, 95% CI: -11.4 to -8.1) and participants who did not report a strong preference at baseline (-11.2 kg, 95% CI: -12.6 to -9.7) (P = 0.04 and P = 0.0004, respectively). Treatment preference did not modify the effect of the treatment on weight loss. Contrary to conceptual predictions, this study failed to identify an interaction between treatment preference and weight loss in the setting of a randomized trial. Until treatment preference effects are definitively ruled out in this domain, future studies might consider stratifying their randomization procedure by treatment preference rather than excluding participants with strong treatment preferences.


Subject(s)
Diet, Reducing/statistics & numerical data , Obesity/diet therapy , Patient Satisfaction/statistics & numerical data , Weight Loss , Diet, Reducing/psychology , Female , Humans , Male , Middle Aged , Obesity/psychology , Reproducibility of Results , Weight Reduction Programs
10.
Diabetes Care ; 34(10): 2297-9, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21873563

ABSTRACT

OBJECTIVE: Metabolic risk and metabolic syndrome (MetSyn) prevalence were compared in Africans who immigrated to the U.S. and African Americans. If MetSyn were an effective predictor of cardiometabolic risk, then the group with a worse metabolic risk profile would have a higher rate of MetSyn. RESEARCH DESIGN AND METHODS: Cross-sectional analyses were performed on 95 men (39 Africans, 56 African Americans, age 38 ± 6 years [mean ± SD]). Glucose tolerance was determined by oral glucose tolerance test, visceral adipose tissue (VAT) was determined by computerized tomography, and MetSyn was determined by the presence of three of five factors: central obesity, hypertriglyceridemia, low levels of HDL cholesterol, hypertension, and fasting hyperglycemia. RESULTS: MetSyn prevalence was similar in Africans and African Americans (10 vs. 13%, P = 0.74), but hypertension, glycemia (fasting and 2-h glucose), and VAT were higher in Africans. CONCLUSIONS: African immigrants have a worse metabolic profile than African Americans but a similar prevalence of MetSyn. Therefore, MetSyn may underpredict metabolic risk in Africans.


Subject(s)
Metabolic Syndrome/epidemiology , Adult , Black or African American , Black People , Blood Glucose/metabolism , Cardiovascular Diseases/blood , Cardiovascular Diseases/epidemiology , Cardiovascular Diseases/physiopathology , Cholesterol, HDL/blood , Cross-Sectional Studies , Glucose Tolerance Test , Humans , Hypertension/blood , Hypertension/epidemiology , Hypertension/physiopathology , Hypertriglyceridemia/blood , Hypertriglyceridemia/epidemiology , Hypertriglyceridemia/physiopathology , Male , Metabolic Syndrome/blood , Obesity/blood , Obesity/epidemiology , Obesity/physiopathology , Risk Factors
11.
J Clin Endocrinol Metab ; 96(8): 2456-63, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21593106

ABSTRACT

CONTEXT: Obesity and diabetes are more common in African-Americans than whites. Because free fatty acids (FFA) participate in the development of these conditions, studying race differences in the regulation of FFA and glucose by insulin is essential. OBJECTIVE: The objective of the study was to determine whether race differences exist in glucose and FFA response to insulin. DESIGN: This was a cross-sectional study. SETTING: The study was conducted at a clinical research center. PARTICIPANTS: Thirty-four premenopausal women (17 African-Americans, 17 whites) matched for age [36 ± 10 yr (mean ± sd)] and body mass index (30.0 ± 6.7 kg/m²). INTERVENTIONS: Insulin-modified frequently sampled iv glucose tolerance tests were performed with data analyzed by separate minimal models for glucose and FFA. MAIN OUTCOME MEASURES: Glucose measures were insulin sensitivity index (S(I)) and acute insulin response to glucose (AIRg). FFA measures were FFA clearance rate (c(f)). RESULTS: Body mass index was similar but fat mass was higher in African-Americans than whites (P < 0.01). Compared with whites, African-Americans had lower S(I) (3.71 ± 1.55 vs. 5.23 ± 2.74 [×10⁻4 min⁻¹/(microunits per milliliter)] (P = 0.05) and higher AIRg (642 ± 379 vs. 263 ± 206 mU/liter⁻¹ · min, P < 0.01). Adjusting for fat mass, African-Americans had higher FFA clearance, c(f) (0.13 ± 0.06 vs. 0.08 ± 0.05 min⁻¹, P < 0.01). After adjusting for AIRg, the race difference in c(f) was no longer present (P = 0.51). For all women, the relationship between c(f) and AIRg was significant (r = 0.64, P < 0.01), but the relationship between c(f) and S(I) was not (r = -0.07, P = 0.71). The same pattern persisted when the two groups were studied separately. CONCLUSION: African-American women were more insulin resistant than white women, yet they had greater FFA clearance. Acutely higher insulin concentrations in African-American women accounted for higher FFA clearance.


Subject(s)
Black or African American/statistics & numerical data , Blood Glucose/metabolism , Fatty Acids, Nonesterified/blood , Glucose Intolerance/ethnology , Glucose Intolerance/metabolism , Insulin/blood , Adipose Tissue/metabolism , Adult , Cross-Sectional Studies , Disease Susceptibility/ethnology , Fatty Acids, Nonesterified/pharmacokinetics , Female , Glucose Tolerance Test , Humans , Middle Aged , Models, Biological , Prevalence , White People/statistics & numerical data
12.
Obesity (Silver Spring) ; 19(10): 1963-70, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21494226

ABSTRACT

The study objective was to evaluate the effect of prescribing a low-carbohydrate diet (LCD) and a low-fat diet (LFD) on food cravings, food preferences, and appetite. Obese adults were randomly assigned to a LCD (n = 134) or a LFD (n = 136) for 2 years. Cravings for specific types of foods (sweets, high-fats, fast-food fats, and carbohydrates/starches); preferences for high-sugar, high-carbohydrate, and low-carbohydrate/high-protein foods; and appetite were measured during the trial and evaluated during this secondary analysis of trial data. Differences between the LCD and LFD on change in outcome variables were examined with mixed linear models. Compared to the LFD, the LCD had significantly larger decreases in cravings for carbohydrates/starches and preferences for high-carbohydrate and high-sugar foods. The LCD group reported being less bothered by hunger compared to the LFD group. Compared to the LCD group, the LFD group had significantly larger decreases in cravings for high-fat foods and preference for low-carbohydrate/high-protein foods. Men had larger decreases in appetite ratings compared to women. Prescription of diets that promoted restriction of specific types of foods resulted in decreased cravings and preferences for the foods that were targeted for restriction. The results also indicate that the LCD group was less bothered by hunger compared to the LFD group and that men had larger reductions in appetite compared to women.


Subject(s)
Appetite , Diet, Carbohydrate-Restricted , Diet, Fat-Restricted , Food Preferences , Obesity/diet therapy , Adult , Behavior, Addictive , Diet, Carbohydrate-Restricted/psychology , Diet, Fat-Restricted/psychology , Dietary Carbohydrates , Dietary Fats , Dietary Proteins , Female , Humans , Male , Middle Aged , Obesity/psychology , Sex Factors
13.
Ann Intern Med ; 153(3): 147-57, 2010 Aug 03.
Article in English | MEDLINE | ID: mdl-20679559

ABSTRACT

BACKGROUND: Previous studies comparing low-carbohydrate and low-fat diets have not included a comprehensive behavioral treatment, resulting in suboptimal weight loss. OBJECTIVE: To evaluate the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program. DESIGN: Randomized parallel-group trial. (ClinicalTrials.gov registration number: NCT00143936) SETTING: 3 academic medical centers. PATIENTS: 307 participants with a mean age of 45.5 years (SD, 9.7 years) and mean body mass index of 36.1 kg/m(2) (SD, 3.5 kg/m(2)). INTERVENTION: A low-carbohydrate diet, which consisted of limited carbohydrate intake (20 g/d for 3 months) in the form of low-glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. A low-fat diet consisted of limited energy intake (1200 to 1800 kcal/d;

Subject(s)
Behavior Therapy , Diet, Carbohydrate-Restricted , Diet, Fat-Restricted , Overweight/therapy , Adolescent , Adult , Aged , Blood Pressure , Body Composition , Bone Density , Exercise Therapy , Female , Humans , Ketone Bodies/urine , Lipoproteins/blood , Male , Middle Aged , Overweight/diet therapy , Overweight/metabolism , Treatment Outcome , Weight Loss , Young Adult
14.
Metab Syndr Relat Disord ; 8(6): 511-4, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20715971

ABSTRACT

BACKGROUND: Compared to whites, insulin-resistant African Americans have worse outcomes. Screening programs that could identify insulin resistance early enough for intervention to affect outcome often rely on triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) levels. Racial differences in TG and HDL-C may compromise the efficacy of these programs in African Americans. A recommendation currently exists to use the TG/HDL-C ratio ≥2.0 to predict insulin resistance in African Americans. The validity of this recommendation needs examination. Therefore, our aim was to determine the ability of TG/HDL-C ratio to predict insulin resistance in African Americans. METHODS: In 1,903 African Americans [895 men, 1,008 women, age 55 ± 12 years, mean ± standard deviation (SD), range 35-80 years, body mass index (BMI) 31.0 ± 6.4 kg/m(2), range 18.5-55 kg/m(2)] participating in the Jackson Heart Study, a population-based study of African Americans, Jackson, Mississippi tricounty region, insulin resistance was defined by the upper quartile (≥4.43) of homeostasis model assessment of insulin resistance (HOMA-IR). An area under the receiver operating characteristic curve (AUC-ROC) of >0.70 was required for prediction of insulin resistance by TG/HDL-C. The optimal test cutoff was determined by the Youden index. RESULTS: HOMA-IR was similar in men and women (3.40 ± 2.03 vs. 3.80 ± 2.46, P = 0.60). Women had lower TG (94 ± 49 vs. 109 ± 65 mg/dL P < 0.001) and TG/HDL-C (1.9 ± 1.4 vs. 2.7 ± 2.1, P < 0.001). For men, AUC-ROC for prediction of insulin resistance by TG/HDL-C was: 0.77 ± 0.01, mean ± standard error (SE), with an optimal cutoff of ≥2.5. For women, the AUC-ROC was 0.66 ± 0.01, rendering an optimal cutoff indefinable. When women were divided in two groups according to age, 35-50 years and 51-80 years, the results did not change. CONCLUSIONS: In African-American men, the recommended TG/HDL-C threshold of 2.0 should be adjusted upward to 2.5. In African-American women, TG/HDL-C cannot identify insulin resistance. The Jackson Heart Study can help determine the efficacy of screening programs in African-Americans.


Subject(s)
Black or African American , Cholesterol, HDL/blood , Coronary Disease/diagnosis , Insulin Resistance , Triglycerides/blood , Adult , Black or African American/statistics & numerical data , Aged , Aged, 80 and over , Body Mass Index , Cholesterol, HDL/metabolism , Cohort Studies , Coronary Disease/blood , Coronary Disease/ethnology , Coronary Disease/metabolism , Female , Humans , Insulin Resistance/physiology , Male , Middle Aged , Mississippi , Prognosis , Triglycerides/metabolism
15.
J Am Coll Cardiol ; 54(25): 2376-81, 2009 Dec 15.
Article in English | MEDLINE | ID: mdl-20082927

ABSTRACT

OBJECTIVES: The objective of this prospective, single-site, 2-year dietary intervention study was to evaluate the effects of moderate weight reduction and subsequent partial weight regain on cardiovascular structure and function. BACKGROUND: Obesity is associated with adverse cardiac and vascular structural and functional alterations. METHODS: Sixty obese subjects (age 46 + or - 10 years, body mass index 37 + or - 3 kg/m(2)) were evaluated during their participation in a weight loss study. Cardiac and vascular ultrasound studies were performed at baseline and at 3, 6, 12, and 24 months after start of intervention. RESULTS: Forty-seven subjects (78%) completed the entire 2-year follow-up. Average weight loss was 7.3 + or - 4.0%, 9.2 + or - 5.6%, 7.8 + or - 6.6%, and 3.8 + or - 7.9% at 3, 6, 12, and 24 months, respectively. Age- and sex-adjusted mixed linear models revealed that the follow-up time was significantly associated with decreases in weight (p < 0.0001), left ventricular (LV) mass (p = 0.001), and carotid intima-media thickness (p < 0.0001); there was also significant improvement in LV diastolic (p < or = 0.0001) and systolic (p = 0.001) function. Partial weight regain diminished the maximal observed beneficial effects of weight loss, however cardiovascular parameters measured at 2 years still showed a net benefit compared with baseline. CONCLUSIONS: Diet-induced moderate weight loss in obese subjects is associated with beneficial changes in cardiovascular structure and function. Subsequent weight regain is associated with partial loss of these beneficial effects. (The Safety and Effectiveness of Low and High Carbohydrate Diets; NCT00079547).


Subject(s)
Carotid Arteries/diagnostic imaging , Heart Ventricles/diagnostic imaging , Ventricular Function, Left/physiology , Weight Gain/physiology , Weight Loss/physiology , Cholesterol, HDL/blood , Diastole/physiology , Diet, Carbohydrate-Restricted , Diet, Fat-Restricted , Echocardiography , Female , Humans , Hypertrophy, Left Ventricular/diagnostic imaging , Hypertrophy, Left Ventricular/physiopathology , Linear Models , Male , Middle Aged , Obesity/physiopathology , Prospective Studies , Systole/physiology , Triglycerides/blood , Tunica Intima/diagnostic imaging , Tunica Media/diagnostic imaging , Ventricular Remodeling
16.
J Clin Sleep Med ; 4(1): 64-5, 2008 Feb 15.
Article in English | MEDLINE | ID: mdl-18350966

ABSTRACT

Patients with insomnia may develop suicidal ideation; however, we know of no reports of suicidal ideation associated with obstructive sleep apnea. We report on a 74-year-old man who presented to his primary care physician with excessive daytime sleepiness, poor quality nocturnal sleep, depressed mood, and suicidal ideation with active suicide plans. An emergency outpatient psychiatry consultation was arranged. The patient declined psychiatric hospitalization. He agreed to a trial of continuous positive airway pressure, using a self-titrating machine, followed by an urgent sleep study. Polysomnography revealed an apnea hypopneaindex of 64, arousal index of 91 and minimum oxygen saturation of 65%. The patient's sleep and excessive daytime sleepiness responded to nCPAP. The patient declined antidepressant medication but had excellent adherence to nCPAP. Suicidal ideation and depression resolved promptly and at 4-month followup were in remission. Further studies examining the relationship among untreated obstructive sleep apnea, depression, and suicidal ideation are warranted.


Subject(s)
Continuous Positive Airway Pressure , Sleep Apnea, Obstructive/therapy , Suicide/psychology , Aged , Depressive Disorder, Major/diagnosis , Depressive Disorder, Major/psychology , Depressive Disorder, Major/therapy , Follow-Up Studies , Humans , Male , Polysomnography , Sleep Apnea, Obstructive/diagnosis , Sleep Apnea, Obstructive/psychology , Treatment Outcome , Suicide Prevention
17.
Am J Clin Nutr ; 84(6): 1317-23, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17158411

ABSTRACT

BACKGROUND: Coronary heart disease (CHD) risk factors increase with age and body mass index (BMI; in kg/m2). However, whether lifestyle intervention ameliorates metabolic CHD risk factors in obese older adults is unknown. OBJECTIVE: The objective was to determine whether lifestyle intervention improves metabolic CHD risk factors in obese older adults. DESIGN: A 6-mo outpatient randomized controlled trial was conducted in obese (BMI >or= 30) older (>or=65 y) adults randomly assigned to diet and exercise therapy (treatment group; n = 17) or no therapy (control group; n = 10). The main outcomes were CHD risk factors. RESULTS: Body weight decreased by 8.4% (8.2 kg) in the treatment group; weight did not change significantly (0.7 kg) in the control group (P < 0.001 between groups). Changes between the control and treatment groups, respectively, in waist circumference (1 and -10 cm), plasma glucose (4 and -4 mg/dL), serum triacylglycerols (0 and -45 mg/dL), and systolic (-2 and -10 mm Hg) and diastolic (0 and -8 mm Hg) blood pressure were different (P < 0.05 for all). The number of subjects with the metabolic syndrome decreased by 59% in the treatment group but did not change significantly in the control group (P < 0.05). Serum free fatty acids increased by 10 micromol/L in the control group and decreased by 99 micromol/L in the treatment group (P < 0.05). Changes between the control and treatment groups, respectively, in C-reactive protein (0.8 and -2.5 mg/L) and interleukin 6 (1.6 and -2.4 pg/mL) were different (P < 0.05 for both). CONCLUSIONS: Lifestyle intervention decreases multiple metabolic CHD risk factors simultaneously in obese older adults.


Subject(s)
Coronary Disease/epidemiology , Diet, Reducing , Exercise/physiology , Life Style , Metabolic Syndrome/epidemiology , Obesity , Age Factors , Aged , Analysis of Variance , Area Under Curve , Blood Glucose/metabolism , Blood Pressure , Body Mass Index , C-Reactive Protein/analysis , Coronary Disease/blood , Female , Health Status , Humans , Interleukin-6/blood , Lipid Metabolism , Male , Metabolic Syndrome/blood , Obesity/blood , Obesity/complications , Obesity/metabolism , Obesity/therapy , Risk Factors , Treatment Outcome , Weight Loss/physiology
20.
Metab Syndr Relat Disord ; 1(4): 299-309, 2003 Dec.
Article in English | MEDLINE | ID: mdl-18370655

ABSTRACT

Low-carbohydrate (LC) weight-reducing diets are popular choices for self-dieters. Eighteen adults (BMI >/= 25 kg/m(2)) were enrolled in this short-term longitudinal study to evaluate dietary intake and weight on their "usual" diets and LC diet. Subjects were instructed to follow the first two phases of the diet described in Dr. Atkins' New Diet Revolution (2 weeks each). Total daily intake of calories and nutrients were calculated from 3-day food diaries. Body weight was measured at the end of each 2-week diet session. All enrolled subjects completed the study (age = 39.8 +/- 8.1 years, BMI = 36.6 +/- 6.6 kg/m(2)). Mean caloric intakes were 1400 +/- 472 kcal/day (Induction diet) and 1558 +/- 490 kcal/day (Ongoing Weight Loss diet) both p

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