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Biomedical subjects

P A Biersteker

Publications and source records attributed to P A Biersteker.

8 recordsLinked to original sources
PubMed1986

Reduction of lung elasticity due to training and expiratory flow limitation during exercise in competitive female rowers.

Lung elasticity and lung volumes at rest were measured in 22 female rowers, in 14 women who just started with rowing, in 21 female cyclists, and in 9 male rowers. The female rowers had a higher specific static and dynamic lung compliance (P less than 0.01) and a lower recoil pressure at functional residual capacity (P less than 0.05) as compared to the other three groups. According to their age, height, and fat-free mass, the female rowers had a normal vital capacity. The residual volume, the functional residual capacity, and the fast expiratory volume in 1 s were also normal. During an increased load test till exhaustion on a bicycle ergometer, the transpulmonary pressure and the expiratory flow were measured. While the expiratory transpulmonary pressure at exhaustion in the female rowers was not markedly lower than in the other groups, expiratory flow did not increase linearly with decreasing expiratory transpulmonary pressure in most of the female rowers. In the other three groups, there was a linear relation between expiratory flow and pressure. The higher lung compliance and lower elastic recoil in the female rowers caused the flow-limiting pressure to be reached at a lower level. The difference in lung elasticity between the male and female rowers showed that the physical stress on the lungs during rowing is not alike in women and men. We assume that the typical female physique requires extra fixation of the trunk during the pull phase of the rowing stroke, which could lead to loss of lung elasticity in female rowers.

Adolescent↗
PubMed1985

Vital capacity in trained and untrained healthy young adults in the Netherlands.

Slow inspiratory vital capacity was measured in 226 healthy young adults, aged from 17 to 35 years. The group included 119 men and 107 women, 87 trained subjects, 71 untrained subjects who intended to take part in a training program for competitive rowing, and 68 untrained subjects who never took part in any competitive sport. The vital capacity increased with height, weight, fat-free mass, height X fat-free mass, and height-independent fat-free mass, with men having significantly higher vital capacities than women of the same height or weight. In both males and females vital capacity showed the best relation with height X fat-free mass (correlation coefficients are 0.78 and 0.57 respectively). Multiple regression on vital capacity with height, weight, fat-free mass, height X fat-free mass, height-independent fat-free mass, percentage body fat, and age increased the correlation coefficient only slightly (0.80 and 0.59 respectively). The subjects had vital capacities that were much higher than those predicted for them by equations originating from the USA. There was no difference between the observed vital capacities and those predicted by equations originating from Europe. There is a difference in vital capacity between the European subjects studied and subjects of similar height studied in the USA. This implies that equations derived from subjects in the USA cannot be applied to European subjects. From our results we conclude that vital capacity is not increased by physical activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1966

Asphyxial potentials of spinal grey matter, and of ventral and dorsal roots.

1. Asphyxial potentials of short latency (from a few to about 10 sec) were recorded with mono- and bipolar electrodes from the cat's spinal cord. Monopolarly, a zone of maximum negativity was found somewhat dorsal of the central canal in the dorsal horn. With bipolar leads potentials of opposite polarity were observed in the dorsal and ventral horns. In the dorsal horn the more ventral electrode tip became negative with respect to the more dorsal one, in the ventral horn the more ventral tip became more positive. In the centre of the cord where the monopolar potential showed a maximum the bipolar potentials were small in either direction, or reversed during asphyxiation.2. These observations can be explained by the development of two independent dipoles of opposite polarity, located in the dorsal and ventral horn respectively, oriented with their negative poles towards the centre of the cord.3. In the ventral as well as in the dorsal root a negativity of a proximal electrode with respect to a more distal one developed during asphyxiation after the same latency as the asphyxial cord potentials. The asphyxial root potentials continued to grow during periods of asphyxiation as long as 30 min, and recovered promptly upon re-oxygenation.4. Ventral and dorsal root potentials were abolished by asphyxiation of the cord for a period of 60 min, 2 weeks previously. This procedure destroys practically all the neurones, but not the dorsal root fibres. The dorsal root potential, but not the ventral one, was abolished by extradural sectioning of the roots, 2 weeks previously.5. The asphyxial ventral and dorsal root potentials were interpreted as the result of depolarization of the intraspinal part of the motoneurones and primary afferent endings respectively, conducted electrotonically along the roots. The short latency of these potentials suggests that an early depolarization of motoneurone, and of the primary afferent end knobs occurs. The latter, which may have some relation to presynaptic inhibition, explains the early failure of synaptic conduction during acute asphyxiation.

Animals↗