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Biomedical subjects

I Astrand

Publications and source records attributed to I Astrand.

At least 19 recordsLinked to original sources
PubMed1988

Physical demands in worklife.

Industrial occupations which are physically strenuous in the traditional sense of the word have decreased in number. They have partly been replaced by "light," repetitive, monotonous work tasks performed in a sitting position. The number of heavy work tasks within the service sector has increased. Specialization has been intensified. The individual's capacity for strenuous work is still of importance to successful work performance. Many studies show that an optional choice of work pace in physically demanding occupational work results in an adaptation of pace or intensity until the worker is utilizing 40-50% of her or his capacity. When the work rate is constrained, the relative strain of the individual varies inversely with the physical work capacity. The frequency of musculoskeletal disorders has concurrently increased with the implementation of industrial mechanization. New, wise, ergonomic moves are needed to stop this development.

Bone Diseases↗
PubMed1981

Exposure to acetone. Uptake and elimination in man.

Eight male subjects were exposed to acetone vapor on two occasions for 2 h in the laboratory. On the first occasion they were exposed to about 1,300 mg/m3 during rest and on the second occasion to about 700 mg/m3 during rest (30 min) and exercise at different work loads on a bicycle ergometer (90 min). The total uptake of acetone was 0.6--1.2 g, and the relative uptake was about 45%. The concentration of acetone in alveolar air was 30--40% of that in the inspiratory air, and it was not affected by exposure time or work load. The concentration of acetone in blood increased continuously with increased uptake during exposure, and there was no tendency towards equilibrium. The half-time of acetone in alveolar air as about 4 h, and in venous and arterial blood it was about 6 and 4 h, respectively. The highest concentrations of acetone in urine were measured 3--3.5 h after exposure. The elimination of acetone via the lungs corresponded to about 20% of the total uptake. Only about 1% of the uptake was excreted via urine.

Acetone↗
PubMed1980

Resting systolic blood pressure and heart rate at work.

A random sample (n = 1050) of the population of a region in central Sweden performed a submaximal exercise test on bicycle ergometers. The participants were men and women aged 18 to 65 taking part in the REBUS study 1969-71 (3). This paper deals with the partial relationship between heart rate at different rates of work and systolic blood pressure measured at rest (SBP) controlling the influence of other predictors of heart rate. It was found that the relationship was non-linear and that individuals with a relatively high SBP had a lower heart rate than individuals with lower SBP. The curvilinear relationship was more pronounced in women and grew stronger with increasing rate of work.

Adolescent↗
PubMed1978

Exposure to xylene and ethylbenzene. I. Uptake, distribution and elimination in man.

Industrial xylene is a mixture of xylene and ethylbenzene. Twelve male subjects were exposed to industrial xylene in inspired air, six subjects in series I to 870 mg/m3 at rest (30 min) and light exercise on a bicycle ergometer (90 min) and six subjects in series II to 435 mg/m3 at rest (30 min) and during exercise of increasing work loads (90 min). The measurements of xylene uptake were performed continuously with the Douglas bag technique. In both series, about 60% of the amount of xylene supplied to the lungs was taken up. In both series, the concentration in alveolar air was relatively low throughout the entire exposure. The relative concentration in alveolar air displayed a linear correlation to the percentage uptake in the lungs. The ratio between the concentration in arterial blood (mg/kg) and alveolar air (mg/l) amounted to 30--40 at the different work loads. The total amount of xylene expired after the exposure was estimated from the alveolar concentration and alveolar ventilation. In series I, with a total uptake of 1.4 g, the subjects expired about 70 mg, i.e., about 5%. The corresponding value in series II was 40 mg of a total uptake of 1.0 g, i.e., about 4%.

Adult↗
PubMed1977

Electrocardiographic findings in men and women aged 18 to 65.

In an epidemiological study--the REBUS study--about 2500 men and women aged 18 to 65 underwent an electrocardiographic (ECG) examination at rest and a subsample of about 1000 persons also performed an ECG exercise test. The ECG recordings were coded according to the modified Minnesota code (2). At rest, 55% of the population had normal ECGs. In the subsample the figure was 65%, indicating a certain selection. During and/or after the exercise test 80% of the men and 70% of the women had no major ST- and T-wave changes, arrhythmias or ectopic beats. In both men and women the percentage of abnormal changes in the exercise ECG rose with age, for the men from 45 years, and for the women from the age of 35. ST depressions were most common abnormal changes recorded. At rest, 20% of the women and 9% of the men had ST depressions. The corresponding figures (major and minor changes) during and/or after the exercise test were 78% and 60% for the women and the men respectively. Out of 184 major ST depressions recorded during the exercise test (codes 4.1--4.4) 14 (7%) were not present immediately after the test. During and/or after the exercise test, 8% of the men and 20% of the women, having no ST changes at rest, had ST changes of the major type. Those subjects who had arrhythmias or ectopic beats at rest, had in general no such changes during and/or after the exercise test.

Adolescent↗
PubMed1976

Exposure to butyl alcohol: uptake and distribution in man.

Twelve subjects were exposed to 300 or 600 mg/m3 of butyl alcohol in inspired air during rest and during exercise on a bicycle ergometer. Exposure lasted 2 h. The results were puzzling in view of the high blood/air partition coefficient for butyl alcohol. The arterial blood concentration was low. The concentration in the last part of the expired air, i.e., the ""alveolar'' concentration, was low. The quotient of ""alveolar'' concentration X 100/inspired concentration was low in relation to the low percentage uptake. However the high solubility of butyl alcohol in water may explain the results. Butyl alcohol was probably partially taken up in the water of the dead space mucous membranes during inspiration. It was then partially released from the membranes. Therefore the concentration of butyl alcohol in the last part of expiration was probably not the same as the concentration in the alveolar air.

Adult↗
PubMed1976

Exposure to trichloroethylene I. Uptake and distribution in man.

Fifteen healthy male subjects were exposed to about 540 and 1,080 mg/m3 of trichloroethylene (TRI) in the air during rest and exercise on a bicycle ergometer. Each subject was exposed during four 30-min periods. The arterial blood concentration increased linearly with the concentration in the alveolar air. The uptake of TRI was about 55% of the supplied amount at rest. At a work load of 150 W during the fourth period the percentage uptake decreased to about 25%. For one fairly thin subject the uptake was near zero at the end of exposure. This development was probably due to the relatively low solubility of TRI in blood and tissues. The uptake of TRI may be estimated from pulmonary ventilation and the concentration in alveolar and inspiratory air.

Adult↗
PubMed1975

Exposure to methylene chloride. I Its concentration in alveolar air and blood during rest and exercise and its metabolism.

Fourteen subjects were exposed to about 870 and 1,740 mg/m3 of methylene chloride in the air during rest and physical exercise on a bicycle ergometer. The duration of each exposure period was 30 min. Each subject was exposed during four periods. The concentration of methylene chloride in the alveolar air increased in the beginning but had a tendency to level off at the end of each period. There was a high correlation between the alveolar and arterial concentration of methylene chloride. The uptake of methylene chloride was about 55 % of the supplied amount at rest, about 40% at a work load of 50 W, and about 30 and 35 % at 100 and 150 W, respectively. The concentration of carboxyhemoglobin (COHb) increased both during and after exposure. With exposure to 1,740 mg/m3 a concentration of COHb in the blood of about 0.85 g/100 ml was reached. This value corresponds to about 5.5 % COHb.

Adult↗
PubMed1975

Exposure to white spirit. I. Concentration in alveolar air and blood during rest and exercise.

Fifteen healthy male subjects were exposed to 1,250 and 2,500 mg/m3 of white spirit in inspiratory air during rest and excercise on a bicycle ergometer. The white spirit contained approximately 83% aliphatic and 17% aromatic components. The duration of each exposure period was 30 minutes. The pulmonary ventilation, the cardiac output, and the concentration of white spirit (subdivided into aromatic and aliphatic components) in alveolar air, arterial blood, and venous blood were determined during and after exposure. The concentration of aliphatic and aromatic components in alveolar air tended to level off towards the close of each period. The resting level of the aromatic components increased approximately 2.0 times, and that of aliphatic components about 2.5 times, during exercise with increased intensities. The concentration of aliphatic components in arterial and venous blood increased at the start of each exposure period but tended to level off towards the close of the period. The resting value increased fourfold in work at the highest intensity. However, the concentration of aromatic components rose sharply during each period. The arterial blood concentration was about 15 times higher at the end of exposure during the heaviest exercise intensity than at rest. Pulmonary ventilation appeared to be more important to uptake in arterial blood than to circulation. The results are believed to be due to the differing solubilities of aliphatic and aromatic components in blood. Measurement of the concentration of white spirit in venous or arterial capillary blood is suggested as a biological check on exposure.

Adult↗