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Biomedical subjects

G L Blackburn

Publications and source records attributed to G L Blackburn.

At least 19 recordsLinked to original sources

Weight cycling.

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Humans

Does the amount of endurance exercise in combination with weight training and a very-low-energy diet affect resting metabolic rate and body composition?

Effects of large (LA; 400 min/wk) and moderate (MA; 200 min/wk) amounts of endurance exercise in combination with weight training (3 d/wk) were compared with the effects of no exercise (C) in 23 obese females after a 12-wk, 3360-kJ/d very-low-energy diet (VLED). The LA group lost 6.5 kg more weight, mainly as fat (6.4 kg), than the C group (P < 0.05). No measurable differences were found among groups for decreases in resting metabolic rate (-729 to -1233 kJ/d; NS) or fat-free mass (-2.9 to -3.9 kg; NS). No improvements in aerobic capacity were achieved with the addition of exercise to a VLED (-0.079 to -0.037 L/min; NS). Strength indexes were improved (+16 to +5 kg; P < 0.05) or maintained with exercise (-3 kg; NS) whereas a loss (-9.3 kg; P < 0.05) or maintenance (+4.5 kg; NS) was found for VLED alone. Large amounts of endurance exercise in combination with weight training added to a VLED appear to improve weight and fat loss compared with a VLED alone.

Adipose Tissue

Comparison of medically supervised and unsupervised approaches to weight loss and control.

The rising incidence of obesity in the United States has given physicians an increased role in its treatment. Although unsupervised programs can produce significant weight losses, the lack of medical supervision increases the potential for health problems. As with other lifestyle changes (for example, smoking cessation and blood pressure control), even minimal physician involvement may enhance outcome. In published clinical trials, the absence of contact with health professionals among control group participants may account in part for their poor success at weight loss or for their weight gain. Smaller trials examining the value of physician advice and encouragement among dieting patients have shown promising results. Physicians should monitor the health of obese and overweight patients during and after weight loss as is appropriate for the patient, depending on caloric levels, rate of weight loss, weight-loss goals, and intercurrent health events. Medical supervision is necessary for patients on very-low-calorie diets, for severely obese patients (body mass index > 35), and for patients with other health problems.

Clinical Trials as Topic

Thermogenesis secondary to transdermal water loss causes growth retardation in essential fatty acid-deficient rats.

Manifestations of essential fatty acid (EFA) deficiency in rats include growth retardation and increased transdermal water loss. The extra metabolic energy requirement could be caused by greater evaporative water loss from the skin surface. To test this hypothesis, 38 weanling rats were randomly assigned to one of two environments, control (CE) at 20 degrees C and 40% humidity or warm/humid (WHE) at 30 degrees C and 90% humidity. Half of the 20 CE rats were fed an EFA-adequate diet and the other 10 an EFA-deficient diet; the 18 WHE rats were also equally partitioned to the two diets. CE and WHE animals were independently group-fed to maintain equal energy intakes within each environment. Weight gain at 90 days was lower for CE EFA-deficient rats than for CE EFA-adequate rats (P < .0001). Growth rates in the WHE to 140 days did not differ. Mean weights at 90 days were as follows: CE EFA-adequate, 196 g; CE EFA-deficient, 148 g; WHE EFA-adequate, 148 g; WHE EFA-deficient, 135 g. In both CE and WHE animals, the triene/tetraene ratio of both serum and liver phospholipids (PL) was 100-fold greater for EFA-deficient versus EFA-adequate diets. PL fatty acids of liver in CE and WHE EFA-deficient rats contained 2.09 and 1.92 micrograms of 20:3 omega 9 per micrograms phosphorus (Pi), respectively, compared with 0.03 and 0.02 microgram 20:3 omega 9/micrograms Pi in CE and WHE EFA-adequate rats. These results indicate equivalent degrees of EFA deficiency in the two environments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Adherence to a dietary fat intake reduction program in postmenopausal women receiving therapy for early breast cancer. The Women's Intervention Nutrition Study.

PURPOSE: To evaluate the feasibility of integrating a program based on dietary fat intake reduction into adjuvant treatment strategies for postmenopausal women receiving therapy for early breast cancer. PATIENTS AND METHODS: Two hundred ninety postmenopausal women with localized (stage I to IIIa) breast cancer receiving conventional systemic therapy provided informed consent and were randomized in a multicenter trial to either a dietary intervention group receiving a program of individualized instruction for reducing total fat intake or a dietary control group with minimal dietary counseling. RESULTS: Significantly reduced (P < .001) fat intake (in terms of percent calories derived from fat) was observed in the intervention group versus the control group at 3 months (20.3% +/- 2.4% v 31.5% +/- 2.6%, mean +/- SD, respectively) and maintained throughout 24 months of observation. The 50% reduction in daily fat-gram intake (from 66 +/- 23 to 33 +/- 14 g, P < .001) seen at 6 months was associated with reduced saturated fat, monounsaturated fat, polyunsaturated fat, and linoleic acid (P < .001). Significantly lower body weight was also seen in intervention compared with control patients at all observation periods, resulting in a 3.3-kg weight difference 18 months after randomization (P < .001). CONCLUSION: Substantial and sustained dietary fat reduction with associated weight change can be achieved at relatively low cost within the context of conventional multimodality clinical management of postmenopausal women with localized breast cancer. This result supports the feasibility of conducting a full-scale evaluation of the influence of dietary fat intake reduction on the clinical outcome of breast cancer patients.

Aged

Adjuvant dietary fat intake reduction in postmenopausal breast cancer patient management. The Women's Intervention Nutrition Study (WINS).

Management of localized breast cancer now commonly involves a breast-sparing approach combined with systemic adjuvant therapy resulting in improved cosmetic results and patient survival. Reducing dietary fat intake represents a conceptually new approach to further improve outcome of patients with resected breast cancer. The rationale supporting evaluation of dietary fat reduction in the management of patients with localized breast cancer is based on: (1) epidemiologic observations (along with biochemical and hormonal correlates) of major differences in stage-by-stage survival of patients with localized breast cancer comparing outcome in countries with low fat (Japan) versus high fat (U.S.A.) dietary intakes; (2) relationships between dietary fat intake and factors prognostic of clinical outcome in patients with established breast cancer; (3) effects of weight gain (especially that associated with adjuvant chemotherapy) on breast cancer clinical outcome; (4) in vivo animal studies demonstrating adverse influence of increased dietary fat intake (especially linoleic acid) on growth and metastatic spread of mammary cancer; (5) direct adverse effects of increased linoleic acid on human breast cancer growth in vitro; (6) plausible mechanisms which could mediate the effects of dietary fat intake reduction on breast cancer growth and metastatic spread; (7) demonstration of adherence to dietary fat reduction regimens in ongoing clinical feasibility studies including those involving postmenopausal patients with resected breast cancer; and (8) favorable sample size requirements for definitive assessment of dietary fat intake reduction influence on breast cancer growth and metastases (using as endpoints relapse-free survival and overall survival) in postmenopausal breast cancer patients with localized disease.

Animals

Impact of gastric restrictive surgery on hypertension in the morbidly obese.

Hypertension is a major health risk factor in patients who are morbidly obese. Two hundred eighty-nine morbidly obese patients undergoing gastric restrictive surgery were evaluated for the presence of hypertension (blood pressure greater than or equal to 160/90 mm Hg or currently undergoing antihypertensive therapy) pre- and postoperatively. Of 74 (26%) preoperatively hypertensive patients, 67 (91%) were available for follow-up. Preoperative hypertension resolved in 66% (44 of 67) of patients following gastric restrictive surgery. Superobese and morbidly obese patients had similar reductions in hypertension after surgery (69% versus 63%). Patients not receiving antihypertensives preoperatively had a greater reduction of hypertension than those medically treated preoperatively (78% versus 58%). The amount of weight loss significantly predicted the reduction of hypertension, whereas follow-up weight achieved did not. The amounts of weight loss for patients with resolved and persistent hypertension were 89.3 +/- 5.6 lbs (mean +/- standard error of the mean +ADSEM+BD) and 66.0 +/- 8.3 lbs, respectively (p less than 0.02). For patients with resolved hypertension, follow-up weights for the morbidly obese and superobese were 162.0 +/- 10.8 lbs (133% +/- 4% ideal body weight +ADIBW+BD) and 220.4 +/- 9.5 lbs (170% +/- 7% IBW). Gastric restrictive surgery is effective therapy for hypertension in morbidly obese patients. Patients need not achieve weights approaching IBW to enjoy the benefits of gastric restrictive surgery on hypertension.

Adult

Influence of omega-3 fatty acids on splanchnic blood flow and lactate metabolism in an endotoxemic rat model.

Alteration in regional blood flow is important in the pathogenesis of organ failure during endotoxemia and sepsis. In particular, intestinal ischemia is thought to enhance the translocation of bacteria into the systemic circulation. We used radioactive microspheres to measure the influence of two intravenous (IV) dietary fats (vegetable oil containing high levels of omega-6 fatty acids, and fish oil containing high levels of omega-3 fatty acids) on regional blood flow during low-dose Escherichia coli endotoxin infusion (0.1 mg/100 g body weight [BW]) in a rat model. Despite absence of changes in the cardiac output, blood flow rates to the small and large intestines, stomach, and pancreas, and also to the skin and skeletal muscle were significantly reduced after 18 hours of endotoxin infusion in the rats fed standard vegetable oil. Short-term IV feeding during a period of 40 hours with an isonitrogenous, isocaloric nutrient solution containing fish oil as the only lipid source normalized intestinal perfusion and increased blood flow to the liver and spleen. Low-dose endotoxin infusion also resulted in significant increases in glucose, lactate, and pyruvate concentrations. In comparison to standard vegetable fat emulsion, fish oil significantly reduced these parameters. A second experiment was conducted to measure lactate kinetics. Based on the dilution of U-14C-lactate, fish oil feeding was associated with higher lactate clearance than standard vegetable oil feeding during the endotoxin infusion. We conclude that short-term IV feeding with fish oil improves intestinal perfusion and portal blood flow, improves glucose tolerance, and increases lactate clearance in a low-dose endotoxin rat model.

Animals

The cost of losing: an analysis of commercial weight-loss programs in a metropolitan area.

Thirty-four million adult Americans are obese (greater than 30% above ideal body weight). 1990 national Health Objectives state that 50% of all adults should adopt weight-loss and exercise regimes. This recommendation has caused a dramatic surge in the number and variety of weight-loss programs currently available. A parallel surge has occurred in the cost of these weight-loss programs. This wide variation in personal expenditure (and treatment provided) necessitates a review of the programs and their cost to the participant. The cost of a 12-week outpatient commercial weight-loss program can range from $2,120 for the most expensive very low-calorie diet program to $108 for the least expensive nutrient-balanced hypocaloric diet program. This article reviews 11 commercial diet programs in the Boston area and analyzes the out-of-pocket cost paid to the clinic by the participant to lose 1 kg on each program. Given the complexity of treatment to achieve long-term weight control, knowledge of financial obligations is important.

Behavior Therapy

Insulin resistance versus insulin secretion in the hypertension of obesity.

We measured the degree of association between obesity, blood pressure, insulin resistance, and insulin secretion in 72 male and female obese hypertensive, obese nonhypertensive, and normal weight control subjects. Baseline weight, body mass index, percent body fat, waist/hip ratio, and systolic and diastolic blood pressures were obtained. Insulin sensitivity was assessed according to Bergman's minimal model. Twelve-hour urinary c-peptide was measured after a standard liquid meal. Insulin action was inversely associated with blood pressure status, obesity status, and age. Meal-stimulated c-peptide excretion significantly correlated with systolic blood pressure and percent fat but not with body mass index or age. Multivariate regression analysis indicated that, of the measures of body composition, percent fat and waist/hip ratio had the strongest correlation with insulin action either alone or in combination with c-peptide excretion. Obese hypertensive patients had an index of insulin action (10(-4).min-1/[microunits/ml]) of 1.34 +/- 0.19, which was significantly (p less than 0.003) lower than in the obese nonhypertensive patients (index, 2.26 +/- 0.10) or the nonobese subjects (index, 5.41 +/- 0.26, p less than 0.001). Meal-stimulated c-peptide excretion (nmol/kg lean body mass) was increased only in the obese hypertensive group (0.32 +/- 0.01) and was significantly higher (p less than 0.001) than in the obese nonhypertensive (0.16 +/- 0.01) or the nonobese subjects (0.14 +/- 0.01). These results support the hypothesis that abnormalities in blood pressure regulation, insulin-stimulated glucose uptake, and insulin secretion coexist.

Adult