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Biomedical subjects

W P Steffee

Publications and source records attributed to W P Steffee.

At least 19 recordsLinked to original sources
PubMed1991

Percent body fat in obese white females predicted by anthropometric measurements.

The percent body fat (PBF) and 15 anthropometric measurements were measured in 221 obese white females randomly assigned to validation and cross-validation groups. Two new anthropometric equations for the prediction of the percent of body fat were generated by multiple regression. Equation 1 includes the residual lung volume (RV) as a factor and had a correlation coefficient (r) of 0.85 and a standard error of the estimate (SEE) of 3.9%. Equation 2 does not include the RV and has an r of 0.82 and an SEE of 4.3%. Both equations were more precise than two previous widely used equations. In a subgroup of 37 subjects who underwent weight loss, equation 1 gave a more precise estimate of the change in PBF. We conclude that the new equations permit a better prediction of the PBF in obese white females.

Adipose Tissue↗
PubMed1986

Microbial growth in clinically used enteral delivery systems.

Potential contamination of enteral formulas has led to the development of policies limiting formula hangtimes. However, enteral administration bags can easily become contaminated during formula refilling. We prospectively studied enteral formula contamination when the hangtime of a prefilled 1000 ml pouch was compared with the standard 4-hour hangtime of a refilled enteral administration bag. Samples of formula collected from different locations along the enteral delivery system were cultured during 57 days of enteral hyperalimentation in 19 patients. The overall enteral formula contamination rate was 61%, where the greatest microbial growth occurred in reconstituted enteral formulas. The presence of microbial growth did not differ between canned formulas administered according to a 4-hour hangtime and the prefilled pouch. Greatest growth in all cases was at the distal tubing hub, where contamination during system manipulation or from the patient probably occurred. Use of prefilled enteral administration bags may delay formula contamination in the administration reservoir. A change in equipment design that would decrease the need to manipulate feeding sets or feeding tube connections should be further investigated.

Aged↗
PubMed1985

Effects of dieting and exercise on lean body mass, oxygen uptake, and strength.

The effects of exercise on lean body mass (LBM), fat mass (FM), maximal oxygen uptake (VO2max), and quadriceps (QD) strength were studied in 72 male, mildly obese (X = 38% fat) subjects (X age, 43.5 yr) randomly assigned to one of eight treatments arranged in a 2 X 4 factorial plan with exercise (EX) and non-exercise (NE) and four diets as the two factors. Exercise consisted of a 3 d/wk, 8-wk aerobics program (70-85% maximum heart rate) accompanied by a calisthenics program. LBM was determined by whole body potassium (40K), FM by subtracting LBM from total body weight, VO2max using the Wilmore-Costill method, and QD strength with the Cybex II system. Weight loss of the combined EX (11.8 +/- 0.6 kg) (X +/- SE) and NE (9.2 +/- 0.3 kg) groups was not statistically different. LBM of the EX group was unchanged (from 63.1 +/- 1.9 to 62.5 +/- 2.1 kg), whereas in the NE group it was reduced from 62.6 +/- 1.1 to 59.3 +/- 1.2 kg (P less than 0.001) accounting for 36% of total weight loss. FM loss was greater for the EX group (11.2 +/- 1.5 kg) when compared to the NE (5.2 +/- 1.6 kg) group (P less than 0.001). The EX group exhibited an increase in VO2max from 2.9 +/- 0.3 to 3.4 +/- 0.2 1 X min-1 (P less than 0.001), whereas the NE group was unchanged (3.0 +/- 0.3 to 2.9 +/- 0.4 1 X min-1 (NS].(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1984

Effects of physical conditioning on self-concept of adult obese males.

The purpose of the study was to investigate possible psychological changes in obese men after participating in an eight-week nutrition and physical conditioning program. The subjects, 45 male, metropolitan policemen who were considered at least 20 percent over their optimum body weights, were placed on diets and received weekly instruction on topics of nutrition and exercise. The subjects were randomly divided into two groups, one that participated in aerobic conditioning and one that did not. The amount of oxygen consumption, as an index of physical fitness, and performance on selected subscales of the Tennessee Self-concept Scale (TSCS) were measured before and after the training and conditioning programs. Both groups displayed significant increases in oxygen consumption and on the Physical Self and Self-satisfaction subscales, but on all these measures, the Conditioning Group increased significantly (2 to 3 times) more. For both groups, the Total Variability measure from the TSCS showed significant reductions, which have been associated with personality integration. These results demonstrate that physical conditioning and dietary educational sessions or educational sessions alone are associated with positive changes in self-concept in obese individuals and also corroborate other studies that show links between physical and psychological fitness.

Adult↗
PubMed1983

Myocardial healing and repair after experimental infarction in the rabbit.

Adequacy of healing after acute myocardial infarction may determine the incidence of postmyocardial infarction rupture and ventricular aneurysm. Accordingly, in 36 rabbits, from 1 to 8 days after coronary ligation, and in 18 shams, we measured collagen formation and mechanical resistance of the infarcted left ventricle to stretch and rupture. Prolyl hydroxylase, an intracellular enzyme of collagen synthesis, increased from control activity of 3970 +/- 431 to 9224 +/- 643 counts/min per mg (cpm/mg) extractable protein (P less than 0.01) at 48 hours and was nearly maximal at 3 days postmyocardial infarction (14,518 +/- 2,030 cpm/mg, P less than 0.01). Lysyl oxidase, an extracellular collagen cross-linkage enzyme, increased from control activity of 29.6 +/- 4.8 to 74.7 +/- 18.8 cpm/mg extractable protein (P less than 0.01) at 72 hours and peaked at 121.5 +/- 7.3 (P less than 0.01) 4-6 days postmyocardial infarction. Hydroxyproline, a measure of collagen content, increased from control of 2.8 +/- 0.2 to 5.3 +/- 0.6 mg/g dry weight (P less than 0.05) at 72 hours and continued to increase at 8 days postmyocardial infarction (14.5 +/- 1.7 mg/g dry weight; P less than 0.01). When enzyme activities and hydroxyproline content were expressed relative to other reference bases, including DNA, tissue protein, dry weight, and total left ventricle, similar results were obtained. The mechanical properties of the infarcted left ventricle were determined by filling a balloon in the excised left ventricle until rupture. The rupture threshold in the normal left ventricle, [664 +/- 43 mm Hg (n = 16)], was not significantly different from that of the infarcted left ventricle on days 1-8 postmyocardial infarction. However, left ventricular rupture occurred more often through the myocardial infarction on days 1-4 postmyocardial infarction (59%) than on days 6 and 8 (18%; P = 0.03) when collagen content had significantly increased. Wall stress at the point of rupture in left ventricles from shams and normals was 30 +/- 2 g/mm2; tensile strength in isolated left ventricle muscle strips was 25 +/- 4 g/mm2 and in isolated scar strips at 7 days postmyocardial infarction was 59 +/- 7 g/mm2. The passive stiffness of the infarcted left ventricle increased from control of 61 +/- 5 to 94 +/- 6 mm Hg/100 microliters (P less than 0.05) at 4 days and 100 +/- 7 mm Hg/100 microliters (P less than 0.01) at 6 days postmyocardial infarction. Stiffness correlated with hydroxyproline content over the 8 days postmyocardial infarction (r = 0.599; P less than 0.001). Thus, the acutely infarcted ventricle was highly resistant to rupture during the initial 48 hours postmyocardial infarction, before any increase in collagen occurred. This result suggests that the preinfarction collagen content has an important role in preventing rupture. After 72 hours postmyocardial infarction, collagen synthesis appeared to be a determinant of infarct stiffness and resistance of the infarcted ventricle to rupture.

Animals↗
PubMed1982

The medical syndrome of obesity.

Obesity is one of the most common medical disorders and perhaps the least responsive to usual medical therapeutic approaches. The syndrome is often defined as greater than 20 per cent above ideal body weight for height; however, vagaries in establishing this relationship result in significant differences in estimates of its incidence. The effects of obesity on health are broad indeed and include many disorders, hypertension being the most consistently associated and potentially most lethal. Despite this significance, the medical practitioner's ability to treat obesity is severely restricted by inadequate training in nutrition, the nearly complete failure of the usually prescribed caloric-restricted diet, and most importantly, the inappropriateness of the mode generally used in medical practice to address the complex interactions between diet, exercise, and behavior that are manifest in obesity. Failure on behalf of the medical community to address the problem has resulted in a commercial industry that consumes billions of dollars annually. Highly ethical, medically based alternatives to these commercial interests do not exist. Perhaps what is needed is the establishment of medical facilities that will provide practicing physicians, dietitians, nurses, and other health professionals with the capacity to bring to bear optimal dietetic intervention, exercise conditioning, and modifications of eating and exercise behavior as therapy for this complex medical disorder.

Adipose Tissue↗
PubMed1981

Nutritional support in renal failure.

The emergence of our ability to intervene nutritionally in the stressed patient has allowed a dramatic alteration in the clinical course of many disorders. Such support should not be denied or restricted to individuals with renal failure. Should acute oliguric renal failure develop, dialysis should be instituted and the patient should be supported to the fullest extent possible. It is most important to remember that support for patients with marginal degrees of renal failure is most common in the hospital setting. The challenge to meet nutrient requirements in the face of a failure in renal regulatory function is great indeed. Should the regulatory function of the kidney be so impaired that the delivery of nutrients is restricted, dialysis should be instituted as a secondary form of support so that nutritional intervention can be accomplished. There is little rationale for severely restricting protein and nutrient intake in any individual in an attempt to maintain low blood urea levels without dialysis. Once dialysis is instituted, near normal nutritional delivery should be maintained. Although many of the foregoing concepts are rational, they have not been tested in a manner to allow critical review by the scientific community. Initial studies using only essential amino acids were compared to glucose alone. More recent retrospective comparisons still have not resolved the controversy. Prospective, randomized controlled trials are needed to compare solutions containing only those amino acids believed to be essential with solutions delivering a more complete array.

Acute Kidney Injury↗
PubMed1977

Protein metabolism in human neonates: nitrogen-balance studies, estimated obligatory losses of nitrogen and whole-body turnover of nitrogen.

1. Aspects of nitrogen metabolism in the human neonate were assessed in one full-term infant and six premature infants by means of nitrogen-balance measurements, estimates of obligatory nitrogen losses and determinations of whole-body nitrogen turnover. 2. Our data indicate that the mean protein requirement for maintenance is 1-1 g of protein day-1 kg-1 and that 3-8 g of protein day-1 kg-1 should be sufficient for adequate growth in healthy premature babies. 3. The mean obligatory urinary, faecal and total nitrogen losses were estimated to be 24, 106, 145 mg day-1 kg-1 respectively. These figures are compared with published values for older infants, and the possible metabolic basis for changes in nitrogen losses during growth and development is discussed. 4. Mean values for whole-body protein synthesis and breakdown were 26-3 +/- 7-0 and 23-8 +/- 7-4 g of protein day-1 kg-1 respectively. Dietary nitrogen intake accounted for 6--18% of the nitrogen flux through the metabolic pool; urea excretion accounted for 2% of the nitrogen flux. 5. The net protein gain, estimated from nitrogen-balanced data, accounted for 9-6% of total daily protein synthesis. 6. These results are discussed in relation to published estimates of whole-body protein synthesis and breakdown at various ages. Their possible significance in the assessment of a "maintenance" requirement for protein and amino acids during the period of rapid growth and development is also considered.

Body Weight↗
PubMed1976

Dietary protein intake and dynamic aspects of whole body nitrogen metabolism in adult humans.

The constant isotope-infusion method of Picou and Taylor-Roberts was used to study rates of total body protein synthesis and breakdown in adult subjects following acute changes in the level of dietary protein intake. Six healthy adults, four males and two females, were studied after adaptation to dietary protein intakes of 1.5 and 0.38 g of protein/kilogram body weight/day. Dietary periods were from 7 to 15 days duration. 15N-glycine was used as a tracer, and was administered orally for 60 hr at 3-hr intervals, or by continuous intravenous infusion for 48 hr. Results were similar for both routes of isotope administration for the comparison conducted at the higher protein intake. At the 1.5-g protein level the mean N flux was 28.2 mg nitrogen/kg/hr, with total body protein (N x 6.25) synthesis and breakdown rates being 3.0 g/kg/day and 2.7 g/kg/day, respectively. Reducing the protein intake to 0.38 g/kg/day caused an 8% decrease (p less than 0.05) in N flux, a 27% increase (p less than 0.005) in the rate of total body protein breakdown, and a 15% increase (p less than 0.05) in the rate of protein synthesis. Endogenous amino acids were reutilized more efficiently under these conditions. The findings are discussed in relation to the way in which adult subjects adapt to acute changes in dietary protein intake.

Adaptation, Physiological↗