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H C Lukaski

Publications and source records attributed to H C Lukaski.

At least 37 records · Page 2Linked to original sources
PubMed1996

Whole-body impedance--what does it measure?

Although the bioelectrical impedance technique is widely used in human nutrition and clinical research, an integrated summary of the biophysical and bioelectrical bases of this approach is lacking. We summarize the pertinent electrical phenomena relevant to the application of the impedance technique in vivo and discuss the relations between electrical measurements and biological conductor volumes. Key terms in the derivation of bioelectrical impedance analysis are described and the relation between the electrical properties of tissues and tissue structure is discussed. The relation between the impedance of an object and its geometry, scale, and intrinsic electrical properties is also discussed. Correlations between whole-body impedance measurements and various bioconductor volumes, such as total body water and fat-free mass, are experimentally well established; however, the reason for the success of the impedence technique is much less clear. The bioengineering basis for the technique is critically presented and considerations are proposed that might help to clarify the method and potentially improve its sensitivity.

Body Composition↗
PubMed1996

Biological indexes considered in the derivation of the bioelectrical impedance analysis.

Although use of the bioelectrical impedance method for the indirect assessment of human body composition is growing, awareness of the theoretical and practical bases of the method is limited. I discuss the relations between impedance variables and biological indexes, describe the biophysical models for the translation of impedance variables into in vivo body-composition indexes, and summarize the influences of physical and biological factors that affect the validity of the bioelectrical impedance method. The practical advantages of the bioelectrical impedance method necessitate concerted research efforts to establish the most appropriate applications of the method in research and clinical medicine.

Body Composition↗
PubMed1996

Functional changes appropriate for determining mineral element requirements.

One factor limiting efforts to determine human requirements for dietary intakes of mineral elements has been the unavailability of acceptable standards for evaluating the effects of marginal and mild deficiencies. Traditional approaches, such as growth, longevity, chemical balance and measurement of concentrations of minerals in plasma or serum and cellular components of the blood, have not been sensitive indicators of mineral nutriture. One alternative that has been shown to be responsive to graded dietary mineral intake is the evaluation of functional responses to specific challenges or stressors. Aberrant responses, either exaggerated or attenuated, to controlled stressors have been observed in a variety of physiological, psychological and immunological parameters when mineral intakes have been suboptimal by conventional standards, compared with adequate responses. In comparison to static biochemical approaches for assessment of mineral nutritional status, functional tests may be sensitive and responsive to alterations in mineral intake in adult humans. Dynamic functional measures complement static biochemical measures and reflect the net effect of deficiencies on integrated biological systems. The application of some of these types of dynamic evaluations of function may be a useful and productive approach for proposing mineral element intakes to optimize human health and biological function and performance.

Adult↗
PubMed1995

Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes?

Mineral elements, including magnesium, zinc, and copper, are required by the body in modest amounts for the maintenance of health and for the development of optimal physiological function. For athletes, adequate amounts of these minerals are required for physical training and performance. Studies of athletes during training, as compared to nontraining control subjects, indicate the potential for increased losses of minerals in sweat and urine. Some studies report suboptimal intakes of minerals, particularly among athletes who are actively attempting to lose weight to meet standards for competition. However, most athletes consume diets that provide adequate amounts of minerals to meet population standards. Athletes should be counseled to consume foods with high nutrient density rather than to rely on mineral supplements. General use of mineral supplements can alter physiological function and impair health.

Copper↗
PubMed1994

Total body water in pregnancy: assessment by using bioelectrical impedance.

Determinations of total body water (TBW) calculated from deuterium dilution spaces and bioelectrical-impedance measurements were made serially in a group of 15 women before, during, and after pregnancy. Similar measurements were made once in a group of 50 nonpregnant women and intermittently in another group of 10 women during pregnancy and postpartum. TBW increased significantly during pregnancy, then decreased postpartum. Estimates of TBW in pregnancy and postpartum calculated with models derived from nonpregnant and pregnant women were similar to measured values. Changes in reactance and resistance explained more of the variance in predicting changes in TBW than did body weight, abdominal circumference, or hematocrit (50-75% vs 4-50%, respectively). Changes in TBW estimated with the nonpregnancy impedance model were significantly different than either the measured changes or changes predicted with the pregnancy impedance model. These findings indicate that the impedance method is a practical and valid method for determining longitudinal changes in TBW.

Adult↗
PubMed1994

The use of bioelectrical impedance analysis (BIA) to estimate body composition in the Diabetes Control and Complications Trial (DCCT).

Although weight gain often accompanies intensive treatment regimens designed to achieve near-normal glycemia in insulin-dependent diabetes mellitus (IDDM), body composition (BC) has not been well studied. Bioelectrical impedance analysis (BIA) is a safe, rapid, and non-invasive method of assessing BC but has not been utilized widely in IDDM. Data from 46 adults with IDDM were used to develop a regression model estimating fat-free body mass (FFM) from bioimpedance measurements obtained using a proximal electrode placement. Reference values of FFM were determined by dual x-ray absorptiometry (DXA). A model using the ratio of height squared to the minimum resistance of 4 limb-lead combinations (H2/R), total body weight, and a weight-gender interaction achieved a high level of accuracy (R2 = 0.982, residual standard deviation = 1.43 kg), while studies of 10 subjects before and after a light meal found no short-term effect of glycemia on measured BIA variables. BIA will therefore be used in combination with waist-to-hip ratios to study the composition and distribution of the increased weight associated with intensive therapy in the DCCT.

Absorptiometry, Photon↗
PubMed1993

In vitro hepatic thyroid hormone deiodination in iron-deficient rats: effect of dietary fat.

The effects of different dietary fats on thyroid indices were studied in weanling iron-deficient rats. Rats were fed one of five different diets (safflower oil with a casein protein source, safflower oil with defatted beef as the protein source, prime rib, beef tallow with casein and stearate with casein). Both dietary fat and iron status (adequate, CN; deficient, ID; or iron-deficient replete, ID-replete) had significant effects on body weight and hemoglobin concentrations. The tallow-fed animals weighed the least relative to animals fed the other fats; ID rats were smaller than CN rats. The tallow- and stearate-fed animals had the highest hemoglobin concentrations. Type of dietary fat affected plasma thyroxine (T4), but not plasma triiodothyronine (T3) or rate of deiodination of reverse T3 (rT3). Iron deficiency decreased plasma concentrations of T3 and T4 and increased in vitro hepatic rT3 deiodination, suggesting that the ID animals tend to metabolize thyroid hormones via deactivating pathways. The alterations in thyroid hormone metabolism associated with iron deficiency are reversible with iron repletion.

Animals↗
PubMed1993

Relationships among swimming performance, body composition and somatotype in competitive collegiate swimmers.

Relationships were determined between sprint swimming performance and estimates of body composition and somatotype components in competitive collegiate swimmers. Forty-three women and 31 men underwent anthropometric and hydrodensitometric measurements at the beginning of a competitive season. There were significant partial correlations (swim stroke was partialed out) between swimming performance (time in a competitive 100-yard swim of each swimmer's major competitive stroke) and height (-0.466, p < 0.01), the mesomorphic (0.404, p < 0.01) and ectomorphic (-0.398, p < 0.01) components of somatotype, percent body fat (0.351, p < 0.05), and fat-free weight (-0.332, p < 0.05) among the women, but no significant correlations among the men. Twenty-three of the women and 21 of the men were also measured and timed at the end of the competitive season. Again, there were significant (p < 0.01) partial correlations (season and stroke were partialed out) between swimming performance and height (-0.766), fat-free weight (-0.657), body weight (-0.437), and the ectomorphic (-0.441) and mesomorphic (0.392, p < 0.01) components of somatotype in women, but no significant correlations among the men. These findings indicate that measurements of body composition and somatotype may be predictors of swimming performance in women but not in men.

Adipose Tissue↗
PubMed1993

Soft tissue composition and bone mineral status: evaluation by dual-energy X-ray absorptiometry.

Dual-energy X-ray absorptiometry (DXA) is a new method for assessing whole-body and regional bone, fat and fat-free mineral-free soft tissue masses. X-rays at two discrete energy levels are collimated and directed into the body. The attenuation of the X-rays by the various chemical components in the body permits determination of important compositional variables. The precision and accuracy of the DXA measurements of bone mineral content and density are 99% and < 1% error, respectively. The reproducibility of the determinations of soft tissue composition is approximately 99%. Because the radiation dose associated with the X-ray exposure is low, DXA is a safe method for routine use in humans. Various applications are described, including an assessment of bone mineral status and body composition in adults and infants. This method is appealing for nutritional studies because it directly determines the composition of bone and of the body.

Absorptiometry, Photon↗
PubMed1992

Impaired thyroid hormone status and thermoregulation during cold exposure of zinc-deficient rats.

Forty-five male, weanling Sprague-Dawley rats were matched by weight into three groups (n = 15). One group was fed ad libitum a semipurified diet containing all essential nutrients and 30 ppm of zinc (control). A second group was fed ad libitum a similar diet but with a deficient zinc intake of less than 1 ppm (ZnD). A third group was pair-fed (PF) the control diet in amounts equal to that consumed by the matched ZnD animals. After 42 days, the animals were fasted for 12 hr then five animals from each group were sacrificed and the remainder was exposed to 3 degrees C for 6 hr. Rectal temperatures were lower (p less than 0.05) in ZnD at 23 degrees C and during cold exposure. Plasma thyroxine (T4) and triiodothyronine (T3) concentrations were reduced (p less than 0.05) at room temperature in ZnD rats. During cold exposure, the ZnD animals had depressed (p less than 0.05) plasma thyrotropin, T4 and T3 concentrations. Thus, ZnD adversely affects thermoregulatory performance of rats acutely exposed to cold by influencing thyroid hormone metabolism.

Adipose Tissue, Brown↗
PubMed1992

Type of dietary carbohydrate affects thyroid hormone deiodination in iron-deficient rats.

The interactive effect of iron deficiency and dietary carbohydrate type on growth and thyroid hormone status of Sprague-Dawley rats was studied. Rats were fed either an iron-adequate (approximately 35 micrograms Fe/g) or an iron-deficient (less than 3 micrograms Fe/g) diet that contained 70% carbohydrate. The carbohydrate sources were 100% cornstarch (STARCH), 85.7% cornstarch and 14.3% sucrose (STARCH/SUCR), 71.4% cornstarch, 14.3% sucrose and 14.3% dextrin (DEXTRIN), or 100% sucrose (SUCROSE). After 4 wk, iron-deficient rats weighed less than the iron-adequate rats and were severely anemic. Total food intake was lower in iron-deficient than in iron-adequate animals; it was also significantly lower in SUCROSE-fed animals relative to other carbohydrate groups. Plasma glucose concentrations were significantly higher in iron-deficient rats than in iron-adequate rats, but plasma thyroid hormones, thyroxine and triiodothyronine, and liver thyroxine monodeiodinase activity were lower. Deiodination of reverse triiodothyronine in liver was unaffected by iron deficiency regardless of carbohydrate treatment. The STARCH-fed animals had higher rates of hepatic thyroxine monodeiodinase activity than rats fed the other dietary carbohydrates. The two main conclusions from this study are that thyroid hormone metabolism is altered by iron deficiency regardless of food intake and that the best purified rodent diet for this type of study would contain a mixture of carbohydrate types to avoid the stimulation of thyroxine monodeiodinase by a 70% cornstarch diet.

Animals↗
PubMed1992

Bioelectrical impedance: a nondestructive method to determine fat-free mass of live market swine and pork carcasses.

Ninety-two swine averaging 104 +/- 4.5 kg and 99 cold carcasses averaging 75 +/- 3.1 kg were measured with a four-terminal plethysmograph. Pigs were transported to the abattoir, fasted 4 h, weighted, and measured for body resistance (Rs, omega), body reactance (Xc, omega), and distance (L, cm) between detector terminals that were located along the dorsal axis of the animal. Pigs were slaughtered 12 h later, carcasses were chilled for 24 h, then weighted (whole carcasses and side carcasses), and cold carcass Rs, Xc, and L measurements were obtained. The right side of the carcass was ground twice, and a 1-kg sample was frozen for later analyses of fat, ash, N, and moisture. Fat-free mass (FFM, kg) was calculated from weight and percentage of fat. Regression analyses were used to develop equations for estimating FFM on a live, adjusted live, whole carcass, and half-carcass basis. Live BW, Rs, and L accounted for the majority of the variation in FFM. Adjusting live BW for head, viscera, and blood weight increased the explained variation for live BW and decreased the variation accounted by Rs. Multiple regression models involving Rs, L, Xc, and weight accounted for 82, 84, and 84% of the variation for FFM expressed on a live, adjusted live, and cold carcass basis, respectively. Results from this study indicate that bioelectrical impedance has excellent potential as a rapid, nondestructive method for estimation of FFM for market swine and pork carcasses.

Abattoirs↗
PubMed1992

Effects of stearic acid and beef tallow on iron utilization by the rat.

Two experiments were done in which anemic rats were fed diets containing safflower oil or stearic acid and low (10 ppm) or adequate (39-42 ppm) iron. Diets were 24% fat by weight. In the stearic acid diets, 2% (Experiment 1) or 4% (Experiment 2) of the fat was supplied by safflower oil to satisfy essential fatty acid requirements. Repletion of hemoglobin, hematocrit, and liver iron was assessed. Compared with safflower oil in both experiments, stearic acid had a significant positive effect (P less than 0.0001) on repletion of hemoglobin (Hb), hematocrit (Hct), and liver iron concentration; the effect on Hb and Hct was most pronounced when dietary iron was low. When expressed as g Hb/mg Fe intake, Hb repletion was affected by a significant interaction between fat and Fe (P less than 0.002) and was greatest in rats fed low iron stearic acid diets. In a third experiment, rats were fed low dietary iron and 24% safflower oil, 20% stearic acid + 4% safflower oil, 3.2% stearic acid + 20.8% safflower oil, or 20% beef tallow + 4% safflower oil. The 20% beef tallow provided 3.2% stearic acid in the total diet. The response of Hb and Hct were similar to those in the first two experiments for rats fed safflower oil or stearic acid. Rats fed beef tallow had significantly greater (P less than 0.05) Hb and Hct repletion than did rats fed safflower oil, although the degree of repletion was less than that observed in rats fed 20% stearic acid. There was no difference in iron repletion of rats fed 3.2% stearic acid and rats fed beef tallow. We conclude that stearic acid enhances iron utilization by rats.

Animals↗
PubMed1992

Rapid bedside method to assess changes in postoperative fluid status with bioelectrical impedance analysis.

BACKGROUND: Estimates of daily postoperative fluid balance usually rely on properly recorded inputs, outputs, and daily weights or clinical signs. These may be imprecise (when poorly done) and are often considered tedious to perform. METHODS: We used bioelectric impedance analysis (BIA) to assess changes in body water shifts in cardiac patients after surgery. Nine consecutively admitted patients undergoing coronary artery bypass (seven men and two women; age range, 43 to 67 years) were studied. Body weight, fluid intake and output, and BIA variables (resistance and reactance) were measured daily. Relationships between body weight and changes in resistance and reactance and net change in fluid balance (in liters per day) were evaluated statistically by regression analysis. RESULTS: Mean body weights changed significantly, reflecting early operative fluid accumulation and later postoperative diuresis; net fluid balance correlated poorly (r = 0.48; p less than 0.05) with body weight, whereas both resistance (r = -0.82; p less than 0.001) and reactance (r = -0.92; p less than 0.0001) correlated highly with net fluid balance. CONCLUSIONS: BIA is useful as an accurate, rapid bedside method for assessing changes in hydration status sequentially after surgery in cardiac patients with complicated fluid shifts.

Adult↗
PubMed1991

Altered metabolic response of iron-deficient women during graded, maximal exercise.

Metabolic responses during a standardized, progressive, maximal work capacity test on a cycle ergometer were studied in 11 women, mean age 28 (SEM 2) years, at admission to the study, after their body iron stores were depleted by diet, phlebotomy and menstruation for about 80 days and after iron repletion by diet for about 100 days, including daily iron supplementation (0.9 mmol iron as ferrous sulfate) for the last 14 days of repletion. Iron depletion was characterized by a decline (P less than 0.05) in hemoglobin, ferritin and body iron balance. Iron repletion, including supplementation, increased (P less than 0.05) hemoglobin, ferritin and iron balance. No changes were observed in cardiovascular and ventilatory responses or peak oxygen uptake. Iron depletion was associated with a reduced (P less than 0.05) rate of oxygen utilization, total oxygen uptake and aerobic energy expenditure, and elevated (P less than 0.05) peak respiratory exchange ratio and post-exercise concentration of lactate. Reduction of body iron stores without overt anemia affects exercise metabolism by reducing total aerobic energy production and increasing glycolytic metabolism.

Adult↗
PubMed1991

The structural, functional, and nutritional adaptation of college basketball players over a season.

The purpose of this study was to determine the structural, functional and nutritional adaptation of college basketball players over a season. Structure was determined by somatotype and body composition, function was determined by peak work capacity and work efficiency, and nutrition was determined by plasma metals analysis. The tests were performed twice on each of the eight subjects, one preseason (PRS) and one postseason (PST). A small structural adaptation was indicated by a mean decrease (less than 1 kg) in fat free weight and an increase in ectomorphy (less than 0.03). Body weight and skinfolds did not change significantly. Functional adaptation was indicated by a one minute decrease in running time for the work capacity test (p less than 0.002), and an increase (p less than 0.02) in VO2 for the work efficiency test. Nutritional adaptation was indicated by a greater mobilization of plasma Zn after exercise during PST than PRS. Plasma Cu apparently was mobilized during exercise in PST but the change during the season (-10 to -6.6%) was not statistically significant because of the large interindividual variability in response. Structural and functional adaptation to basketball training over a collegiate season is small; however, the change in Zn mobility and the tendency for a concomitant change in Cu mobilization offers a unique finding to help explain the nutritional adaptation to training.

Adaptation, Physiological↗
PubMed1991

Effects of participation in a collegiate sport season on body composition.

Fifty-three collegiate athletes (18 female and 35 male) were recruited from university varsity basketball, football, swim, and wrestling team rosters. Body composition was estimated before the beginning and before the end of sport seasons by using hydrodensitometry to determine the effect of participation in competitive sport seasons on the body composition of collegiate athletes. ANOVAs applied to the estimates of body composition indicated that the interaction of sport team by season was significant for body weight, F (5,47) = 3.2, p less than 0.05; fat weight, F (5,47) = 5.1, p less than 0.01; and fat-free weight, F (5,47) = 2.4, p less than 0.05. Only football players did not change in body composition. Wrestlers lost the greatest amount of body weight (3.4 kg). Female and male basketball players, female and male swimmers, and wrestlers lost significant amounts of body fat (2.6, 2.3, 1.8, 2.7, and 3.6 kg, respectively). Female and male basketball players and female and male swimmers gained significant amounts of fat-free weight (2.0, 1.6, 2.4, and 1.8 kg, respectively). It was concluded that participation in a collegiate sport season could affect changes in fat weight and fat-free weight components of body composition but that the nature of the changes are a function of the demands of the sport of participation.

Basketball↗