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Biomedical subjects

L Garby

Publications and source records attributed to L Garby.

17 recordsLinked to original sources
PubMed1991

Within-subjects variation over 10 months in 24-hour energy expenditure at a fixed physical activity programme.

In order to estimate within-subjects variability in 24-hour energy expenditure at a fixed physical activity programme with a physical activity index of 1.30, this quantity was measured in four apparently healthy subjects once a month over 10 months. The coefficient of variation of the measurements was found to be between 2.7 and 4 per cent and in agreement with previously published data.

Adipose Tissue↗
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↗
PubMed1977

Effect of the preceding day's energy intake on the total energy cost of light exercise.

The effect of a variation in the preceding day's dietary energy intake-4, 10 and 18 MJ-on the oxygen consumption and respiratory quotient at rest and at work before and after a test meal (4 MJ) was investigated. 7 normal male subjects were studied at 3 different experimental situations. During the first day the subjects had an energy intake of 10 MJ and normal activity. The following morning measurements of V(O2) and V(CO2) were performed at rest and at work on a bicycle ergometer (36 W) before and after the test meal. The same measurements were performed on the following day but the dietary intake between the two sets of measurement was then either 6, 0 or 14 MJ. No significant effect was found of the preceding day's dietary energy intake on the oxygen consumption or on the energy transformed during rest, during exercise before and after the test meal. The results do not support the conclusions of previously published studies, proposing a significant feed-back mechanism tending to control the body energy content by regulation of the energy expenditure through chemical or mechanical uncoupling.

Adult↗
PubMed1977

The molecular function of hemoglobin as reflected in ligand binding data: analysis of data on erythrocytes.

Hemoglobin oxygen binding data on erythrocytes at diffrent pH, PCO2 and bisphosphoglycerate concentrations have been analyzed in terms of an extended version of the Herzfeld-Stanley model of 1972. The binding of oxygen to subunits when the tetramer is in the quaternary oxy conformation was found to be insensitive to moderate changes in pH and pCO2 (0.71 +/- 0.05 mm Hg-1). Utilizing this circumstance it has been possible to obtain, for the first time, unique estimates of energy parameters related to hemoglobin cooperativity and effector action. At 37 degrees C, pH 7.2 and pCO2 22 mm Hg the following parameter values were obtained: The allosteric constant: (1.5 + 0.4)-10(4); the oxygen binding constant of the deoxy state: (5.4 +/- 0.3).10(-3) mm Hg-1; the 2,3-bisphosphoglycerate binding constants: (3.3 +/- 1.3).10(3)1. mol-1(deoxy), (1.3 +/- 0.5).10(2)1. mol-1 (oxy). Quarternary transition most likely takes place after binding of the second O2 molecule. Following the concepts of Perutz the results suggest that (1) protons and carbon dioxide act as constraint effectors and/or as quaternary effectors; (2) the difference in total conformational energy between the two quaternary ligand-free states is almost exclusively confined to molecular constraints and very little to the difference in quaternary conformational energy. The consistency of the results indicate that the model may be regarded as a useful tool for the description of the functional interrelations in the hemoglobin oxygenation process as reflected in oxygen binding data.

Binding Sites↗
PubMed1976

A theoretical model of the respiratory function of blood.

The model of the respiratory function of blood as outlined here is judged to be a powerful tool for the evaluation of the potential effects of changes in blood as well as tissue parameters upon the supply of oxygen to tissue. The erythrocyte-plasma disequilibria in lung and systemic capillaries which is a consequence of the slowness of plasma CO2 hydrolysis are not significant in terms of the delivery of oxygen to tissue, but result in slightly lower unloading of CO2 in the lungs compared to that which might occur at full equilibration. However, the effects might be of greater interest when relating pH values measured by in vivo sampling to actual values prevailing within the capillaries. The physiological importances of hyperventilation and elevated DPG levels in anemia cannot as yet be clarified. If anything, it appears that increased DPG is a compensatory mechanism to restore proper O2-Hb affinity in alkalosis, while the purpose for an alkalosis is not obvious.

Anemia↗
PubMed1975

The blood oxygen transport system. A numerical simulation of capillary-tissue respiratory gas exchange.

A theoretical model of the process of respiratory gas exchange between capillary and tissue is described, with special reference to the importance of variations in blood properties. The volume of tissue supplied with oxygen from a single vessel, as a function of the blood flowrate (u), hematocrit (h), and 2,3 diphosphoglycerate concentration (DPG), is calculated from a solution to the set of equations governing species distributions in the blood and tissue. The results, which are presented in the form of crossplots of the three blood parameters (u, h, and DPG) at a constant oxygen supply rate, show the possible significance of in vivo variations in the oxygen affinity of hemoglobin as a compensatory mechanism. Of further physiological interest is the sharp increase in venous erythrocyte pH in response to decreases in hematocrit, once the hematocrit is below a certain level. These results, and those relating DPG to hematocrit at constant O2 supply, are consistent with experimental observations of elevated DPG and pH levels in anemic individualts, and the dependence of erythrocyte DPG concentration upon pH.

Capillaries↗