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Biomedical subjects

L Garby

Publications and source records attributed to L Garby.

At least 55 records · Page 3Linked to original sources
PubMed1985

Effect of trunk load on the energy expenditure of treadmill walking and ergometer cycling.

Data concerning the effect of trunk loads on the energy expenditure of various activities are scanty and partly conflicting. The energy expenditure of walking (4.5 km hr-1, 1.5% inclination) and ergometer cycling (60 watt, 60 rpm) was measured in 23 apparently healthy subjects with and without a trunk load of 10% of the body weight. For walking, the increment in energy expenditure per kg of load was 2.55 +/- 0.25 watt, while the increment per kg of body weight was 4.01 +/- 0.45 watt. For ergometer cycling, the increment per kg of load was 1.12 +/- 0.64 while that per kg of body weight was 2.73 +/- 0.56 watt. Prediction of energy expenditure for trunk loads has previously been made on the basis of the relation between energy expenditure and body weight. Our data show that this may lead to considerable overestimation.

Adult↗
PubMed1985

A 24-m3 direct heat-sink calorimeter with on-line data acquisition, processing, and control.

The construction and performance of a 24-m3 direct heat-sink calorimeter for continuous measurement of evaporative and sensible heat loss in human subjects are described. Extensive use of real-time processing for compensation of physical time constants and delays made it possible to solve response-time and stability problems associated with the large volume. The performance characteristics of the calorimeter are 1) a linear response between 0 and 320 W (471 g . h-1) for evaporative heat with a precision of 4.0-0.6% in the range 25-100 W, 2) a linear response between 0 and 280 W for sensible heat with a precision of 1.4-0.2% in the range 50-200 W, 3) a stability corresponding to a drift of less than 0.6 W (24 and 72 h) on both evaporative and sensible heat outputs and 24- and 72-h standard deviations (values every 2 min) of 0.3 and 0.4 W for evaporative heat and 0.6 and 0.7 W for sensible heat, 4) response times (95%) of 15 min for both evaporative and sensible heat, 5) independency on the position of the calibration source within the chamber, 6) no measurable "cross talk" between evaporative and sensible heat inputs, 7) negligible dependency of the external air humidity between 14 and 70%, and 8) operating temperature range from 18 to 30 degrees C. More than 40 experiments of 25-h duration with human subjects have been carried out. In no case was any discomfort recorded. An example of the 25-h continuous evaporative and sensible heat output tracing of one experiment is given.

Body Temperature↗
PubMed1985

Relationship between energy expenditure, expressed as the physical activity index, and body weight at low physical activity programmes.

The physical activity index, PAI, is defined as the energy expenditure, EE, divided by the resting metabolic rate, RMR. An expression for the body weight dependency of PAI, ie, dPAI/dBW = K, is derived. Numerical values for this coefficient were calculated on the basis of six published papers using whole-body calorimetry with observations over 24 h. It was found to be around -0.0022 per kg body weight difference in the PAI range between 1.25 and 1.70.

Body Weight↗
PubMed1984

Principles and problems of human energy exchange.

The principles and laws that determine the relations between observed quantities in experiments on human energy exchange are described in terms of classical thermodynamics applied to an open system. It is suggested that adherence to such a description will help avoid ambiguities and imprecision in analysis of the data. The description suggests a framework within which the control aspects of the system can be profitably analyzed.

Energy Metabolism↗
PubMed1984

Numerical values of the classical Haldane coefficient.

Values of the classical Haldane coefficient, i.e, the change in the concentration of total CO2 in whole blood per unit of change in the concentration of total O2 at constant PCO2, have been calculated at different combinations of plasma pH (range 7.25-7.50), erythrocyte 2,3-diphosphoglycerate (DPG) concentration (range 3.5-6.5 mM), PCO2 (range 25.0-65.0 Torr), initial hemoglobin O2 saturation (range 0.50-0.80), and erythrocyte volume fraction (range 0.25-0.55). The principle of the calculations is to utilize the so-called reciprocity relations to determine the amount of protons and CO2 released from hemoglobin on oxygenation and to estimate the resulting change in the concentration of total CO2 from published data on the interaction coefficient for the binding of O2 and protons to hemoglobin, the interaction coefficient for the binding of O2 and CO2 to hemoglobin, the distribution of protons across the erythrocyte membrane, the equilibrium constants for the reactions between CO2 and H2O, and CO2 and oxyhemoglobin, the buffer capacity of oxygenated erythrolysate, and the buffer capacity of plasma. The results show that the concentrations of the allosteric ligands, DPG, protons, and CO2 have a significant influence on the numerical value of the Haldane coefficient. Furthermore, the coefficient depends on the hemoglobin O2 saturation and the erythrocyte volume fraction. The dependency of the Haldane coefficient on the O2 saturation and the PCO2 causes an increase in the O2-linked CO2 flux across the alveolar membrane by more than 30% in patients with respiratory insufficiency.

2,3-Diphosphoglycerate↗
PubMed1984

Within-subjects between-weeks variation in 24-hour energy expenditure for fixed physical activity.

The energy expenditure of eight male subjects over 24 h on a fixed activity programme was measured twice at an interval of one week in a 24 m3 direct calorimeter. The standard deviation of a single measurement of the total heat output was 234 kJ, or 2.2 per cent, expressed as a coefficient of variation. The corresponding numbers for sensible and evaporative heat output were 215 kJ (3.2 per cent) and 354 kJ (9.3 per cent), respectively. The within-subjects coefficient of correlation of sensible and evaporative heat loss was -0.77. The results are in agreement with previously published results (Dallosso, Murgatroyd & James, 1982) using indirect calorimetry and show that the 24-h energy expenditure on a fixed programme is a remarkably constant quantity. Furthermore, our data show that the two components of heat dissipation, ie, sensible and evaporative heat, are negatively coupled, indicating that the body can sense and communicate the activity of both effector organs.

Activity Cycles↗
PubMed1984

Within-subjects between-days-and-weeks variation in energy expenditure at rest.

Determinations of energy expenditure at rest were performed in 22 apparently healthy male subjects twice with one day's interval, and in 23 apparently healthy male subjects with one week's interval. In both series of experiments, the error of the method was calculated from multiple determinations on the same occasion. The coefficients of variation due to time were calculated and found to be 2.4 and 2.2 per cent, respectively. These numbers are practically identical to that found for the within-subject between-weeks variation in 24-h energy expenditure experiments using whole body calorimeters (Garby, Lammert & Nielsen, 1984).

Activity Cycles↗
PubMed1979

An analysis of factors leading to a reduction in iron deficiency in Swedish women.

The prevalence of iron deficiency anaemia among Swedish women of child-bearing age has fallen markedly since the mid-1960s. At that time, population studies in Göteborg and Uppsala showed that iron deficiency anaemia was present in about 25-30% of women. Later, in population studies in Göteborg in 1968-69 and 1974-75, the prevalence in the same age group was found to have fallen to 6-7%. Several factors may explain the improved iron status. The level of iron fortification of flour was increased from 30 mg/kg of flour in 1943 to 65 mg in 1970, this increase adjusting the iron intake to compensate for the lower energy requirement and expenditure of present-day living habits. There has also been a marked increase in the intake of iron tablets and of tablets containing ascorbic acid.An analysis of various factors indicates that the 20-25% improvement in iron status can be accounted for by increased use of oral contraceptives (3-4%), the impact of increased iron fortification (7-8%), the widespread use of ascorbic acid supplements (3%), and greater prescribing of iron tablets (10%).This analysis of the factors leading to the marked reduction in the prevalence of iron deficiency anaemia among Swedish women may be useful to public health planners in other countries with similar problems. Our results indicate that several factors need to be considered when planning controlled field trials and evaluating the results obtained. The methods used to analyse the impact of different factors on the reduction in iron deficiency can also be used to predict the effects of various public health measures on the iron status of a population.

Adolescent↗
PubMed1978

Iron absorption from South-East Asian diets and the effect of iron fortification.

The increase in iron absorption was measured when different amounts of ferrous sulphate were added to rice-based South-East Asian meals. The study comprised 158 subjects--118 women and 40 men. Iron fortification of simple meals composed of rice, boiled vegetables, and a curry to a level of 5 mg of iron per meal increased the absorption by about 0.2 to 0.3 mg of iron per meal. The additionof fish to such a meal doubled the absorption increase at a fortification level of 5 mg per meal. This absorption increase was about the same as obtained with composite western-type meals containing fish or meat. The results indicate that iron fortification programs may be effective in countries with rice-based diets provided that there is a suitable vehicle available for fortification.

Absorption↗
PubMed1978

Absorption from iron tablets given with different types of meals.

The absorption of iron from tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given.

Administration, Oral↗
PubMed1978

A note on the single injection residue function method to determine capillary permeability.

The assumption inherent to the single injection residue function method to determine capillary permeability have been made explicit. Furthermore, it is shown that agreement between the deduced wash-out function of the transmitted molecules of the test substances and that of reference molecules does not constitute proof of the validity of the method.

Capillary Permeability↗