George L. Blackburn

Reduction in weight and cardiovascular disease risk factors in individuals with type 2 diabetes: one-year results of the look AHEAD trial.

OBJECTIVE—The effectiveness of intentional weight loss in reducing cardiovascular disease (CVD) events in type 2 diabetes is unknown. This report describes 1-year changes in CVD risk factors in a trial designed to examine the long-term effects of an intensive lifestyle intervention on the incidence of major CVD events. RESEARCH DESIGN AND METHODS—This study consisted of a multicentered, randomized, controlled trial of 5,145 individuals with type 2 diabetes, aged 45–74 years, with BMI >25 kg/m2 (>27 kg/m2 if taking insulin). An intensive lifestyle intervention (ILI) involving group and individual meetings to achieve and maintain weight loss through decreased caloric intake and increased physical activity was compared with a diabetes support and education (DSE) condition. RESULTS—Participants assigned to ILI lost an average 8.6% of their initial weight vs. 0.7% in DSE group (P < 0.001). Mean fitness increased in ILI by 20.9 vs. 5.8% in DSE (P < 0.001). A greater proportion of ILI participants had reductions in diabetes, hypertension, and lipid-lowering medicines. Mean A1C dropped from 7.3 to 6.6% in ILI (P < 0.001) vs. from 7.3 to 7.2% in DSE. Systolic and diastolic pressure, triglycerides, HDL cholesterol, and urine albumin-to-creatinine ratio improved significantly more in ILI than DSE participants (all P < 0.01). CONCLUSIONS—At 1 year, ILI resulted in clinically significant weight loss in people with type 2 diabetes. This was associated with improved diabetes control and CVD risk factors and reduced medicine use in ILI versus DSE. Continued intervention and follow-up will determine whether these changes are maintained and will reduce CVD risk.

Infusion of tumor necrosis factor/cachectin promotes muscle catabolism in the rat. A synergistic effect with interleukin 1.

To improve our understanding of the metabolic role of cytokines in protein wasting, we estimated the rates of protein synthesis and degradation in muscle and liver tissues in intact rats treated with several doses of recombinant IL 1 and/or tumor necrosis factor (TNF)/cachectin. Protein breakdown in muscle and liver were derived in vivo from the relationship between [14C]leucine distribution and tissue dilution in reference to circulating leucine. Synthesis was derived from the relationship between [14C]leucine appearance in the protein-bound and free-tissue leucine pools. To specifically relate changes in leucine tracer metabolism to protein dynamics, we separately measured the effect of these cytokines on blood flow to different tissues. The increase in dilution of the tissue-free [14C]leucine by TNF and TNF/IL 1 mixture, but not by IL 1 alone, could not be explained by a hemodynamic effect of these cytokines. Rather, this finding indicated that muscle proteolysis is enhanced by TNF and synergistically augmented by the addition of IL 1. Compatible with these data was the finding that more prolonged infusions of recombinant TNF/cachectin and the combination with IL 1 increased urinary nitrogen excretion. Changes in [14C]leucine dilution in the liver were less pronounced than those in skeletal muscle and consistent with net anabolic effect of TNF on liver protein. We conclude that rats exposed systemically to sublethal doses of TNF respond with increasing muscle and decreasing liver proteolysis, similar to that observed in inflammation and in cancer.

The Risks of Surgery in Obese Patients

Obesity is commonly considered a surgical risk factor, but the degree of risk has been imprecisely quantified. There is little evidence that excessive body weight in itself should contraindicate general surgery. However, obesity is often associated with abnormal cardiorespiratory function, metabolic function, and hemostasis, which may predispose to morbidity and mortality after surgery. We review pertinent data and offer guidelines to minimize the risks of surgery in obese patients.

Reduced Activity of the Red-Cell Sodium-Potassium Pump in Human Obesity

Looking for evidence of reduced energy use in the cells of obese persons, we measured the numbers of sodium-potassium-pump units in erythrocytes from a group of 21 obese human subjects and found them to be reduced by 22 per cent as compared with those of nonobese controls (P <0.001). The cation-transport activity of the pump, as measured by 86rubidium uptake by the cells, we also reduced in parallel with decrease in pump units. An increased concentration of sodium in the red cells of obese subjectes was also found (9.6 +/- 0.7 vs. 7.1 +/- 0.6 mmol per liter of cells; P<0.01). This finding demonstrates independently the physiologic importance of reduced numbers of sodium-pump units and reduced pump activity as measured by ouabain binding and rubidium transport, respectively. The magnitude of the reduction in the number of pump units was found to be negatively correlated with the percentage of ideal body weight (r = 0.56, P<0.001); this observation suggests a possible role of abnormalities of the sodium pump in the pathophysiology of obesity.

Nutritional assessment of the hospitalized patient.

While some symptoms of the malnourished state are obvious, others may be subtle. In either case, assessment is indicated to uncover any inconspicuous symptoms and secondly to quantitate those that are apparent. Such procedures are pertinent because immune competence and other organ systems related to survival are dependent on the adequately nourished state. It is also important to remember that certain vitamin and mineral deficiencies may accompany protein calorie malnutrition and thus their attention would be especially needed during the repair of this condition. The deficiencies seen most often include vitamins C, A, and D, as well as zinc, copper, and calcium. Furthermore, the refeeding process may also precipitate shortages of potassium, phosphate, and magnesium, unless adequate amounts of these nutrients are included in the diet. From this and earlier discussed situations, it is suggested that nutritional assessment should be the initial step in nutritional therapy. It should be approached with concern not only for what the collective assessment tools will reveal, but also with consideration for the patients clinical problem, the current metabolic situation and the projected therapeutic regimen which will be formulated.

The human metabolic response to chronic ketosis without caloric restriction: Preservation of submaximal exercise capability with reduced carbohydrate oxidation

To study the effect of chronic ketosis on exercise performance in endurance-trained humans, five well-trained cyclists were fed a eucaloric balanced diet (EBD) for one week providing 35-50 kcal/kg/d, 1.75 g protein/kg/d and the remainder of kilocalories as two-thirds carbohydrate (CHO) and one-third fat. This was followed by four weeks of a eucaloric ketogenic diet (EKD), isocaloric and isonitrogenous with the EBD but providing less than 20 g CHO daily. Both diets were appropriately supplemented to meet the recommended daily allowances for vitamins and minerals. Pedal ergometer testing of maximal oxygen uptake (VO2max) was unchanged between the control week (EBD-1) and week 3 of the ketogenic diet (EKD-3). The mean ergometer endurance time for continuous exercise to exhaustion (ENDUR) at 62%-64% of VO2max was 147 minutes at EBD-1 and 151 minutes at EKD-4. The ENDUR steady-state RQ dropped from 0.83 to 0.72 (P less than 0.01) from EBD-1 to EKD-4. In agreement with this were a three-fold drop in glucose oxidation (from 15.1 to 5.1 mg/kg/min, P less than 0.05) and a four-fold reduction in muscle glycogen use (0.61 to 0.13 mmol/kg/min, P less than 0.01). Neither clinical nor biochemical evidence of hypoglycemia was observed during ENDUR at EKD-4. These results indicate that aerobic endurance exercise by well-trained cyclists was not compromised by four weeks of ketosis. This was accomplished by a dramatic physiologic adaptation that conserved limited carbohydrate stores (both glucose and muscle glycogen) and made fat the predominant muscle substrate at this submaximal power level.

Total parenteral nutrition and cancer clinical trials

Twenty‐eight prospective randomized controlled clinical trials evaluating the use of total parenteral nutrition (TPN) in cancer patients were identified through a search of major indexing sources. The data were pooled across studies to increase the ability to detect therapeutic effects. The impact of publication bias and the quality of reporting each trial were used to critically assess the conclusions drawn from the pooled analysis. The authors conclude that TPN may be useful when used preoperatively in patients with gastrointestinal tract cancer. It appears to be beneficial in reducing major surgical complications (pooled P = 0.01) and operative mortality (pooled P = 0.02). No statistically significant benefit from TPN could be demonstrated in survival, treatment tolerance, treatment toxicity, or tumor response in patients receiving chemotherapy or radiotherapy. An increase in the risk of developing an infection in chemotherapy patients given TPN (pooled P > 0.0001) underscores the importance of demonstrating significant benefits in randomized trials before TPN is used routinely in these patients.

Obesity and its comorbid conditions.

Obese patients are at an increased risk for developing many medical problems, including insulin resistance and type 2 diabetes mellitus, hypertension, dyslipidemia, cardiovascular disease, stroke, sleep apnea, gallbladder disease, hyperuricemia and gout, and osteoarthritis. Certain cancers are also associated with obesity, including colorectal and prostate cancer in men and endometrial, breast, and gallbladder cancer in women (1-6). Excess body weight is also associated with substantial increases in mortality from all causes, in particular, cardiovascular disease. More than 5% of the national health expenditure in the United States is directed at medical costs associated with obesity (7). In addition, certain psychologic problems, including binge-eating disorder and depression, are more common among obese persons than they are in the general population (8.9). Finally, obese individuals may suffer from social stigmatization and discrimination, and severely obese people may experience greater risk of impaired psychosocial and physical functioning, causing a negative impact on their quality of life (10).

Central venous catheterization for parenteral nutrition.

To define the risks associated with central venous catheterization for total parenteral nutrition (TPN) 3291 patient days of this therapy, delivered by an established nutrition support team, were evaluated. One hundred and seventy-five catheters placed in 104 patients were reviewed over an 18 month period. Positive cultures were reported on 11 cannulae for a 6.4% incidence of colonization; five catheters (2.8%) were considered septic. Pleural or mediastinal complications of subclavian or internal jugular venipuncture occurred in eight patients (4.8%). Misdirection of the catheter tip occurred in 11.5% of insertions. Five patients (4.8%) had clinically apparent thrombosis in the superior vena cava, innominate and/or subclavian veins during hospitalization; four others had evidence of thrombosis at autopsy examination, giving an incidence of 8.7% in the entire series. No death directly resulted from the use of this therapy. Compliance with a rigid protocol by an experienced team can allow safe and effective use of central venous catheters and parenteral nutrition therapy.

Monitoring Dietary Change in a Low-Fat Diet Intervention Study: Advantages of Using 24-Hour Dietary Recalls vs Food Records

OBJECTIVE The purpose of the study was to evaluate two methods of dietary assessment for monitoring change in fat intake in a low-fat diet intervention study. DESIGN The two dietary assessment methods were a 4-day food record (4DFR) and an unannounced 24-hour dietary recall conducted by telephone interview (referred to as a telephone recall [TR]). Subjects were assigned randomly to either a low-fat diet intervention group or a control group that received no counseling about fat intake. Dietary data were collected at baseline, 6 months, and 12 months. SUBJECTS Two hundred ninety postmenopausal women with localized breast cancer were recruited at seven clinical centers in the United States. STATISTICAL ANALYSIS Analysis of variance was used to test for significant differences in mean fat and energy intakes. RESULTS Three sources of error were identified: (a) an instrument effect, suggesting underreporting at baseline of approximately 8% in mean energy intake and 11% in mean fat intake in the TR group compared with the 4DFR group (P = .0001); (b) a repeated measures effect observed for the 4DFR, suggesting underreporting of approximately 7% for energy intake and 14% for fat intake in the control group at 6 and 12 months compared with baseline values (P < .001); and (c) an adherence effect (or compliance bias), suggesting greater compliance to the low-fat intervention diet when subjects were keeping food records than when estimates were based on the unannounced TR. Compared with the TR, the 4DFR overestimated the extent of fat reduction in the low-fat diet intervention group by 41% (P = .08) and 25% (P = .62) at 6 and 12 months, respectively. APPLICATION Multiple days of unannounced 24-hour recalls may be preferable to multiple-day food records for monitoring dietary change in diet intervention studies.