Die fortlaufende,unblutige Blutdruckregistrierung unter Verwendung eines mechanisch-elektrischen Transducers

Zusammenfassung Es wird ein Manometer beschrieben, das den Blutdruck des Menschen unblutig und fortlaufend bei Ruhe und Arbeit registriert. Mit Hilfe der Wagnerschen Manschette wird über der art. radialis ein starrer Raum geschaffen, der durch eine Plexiglasplatte mit großem Volumenelastizitätsmodul abgeschlossen ist. Der Raum über der Arterie wird mit soviel Glycerin luftblasenfrei gefüllt, daß die Arterienwand entspannt wird. Der Druck in dem Raum ist dann dem Arteriendruck gleich. Die Starrheit der Wände und der große Volumenelastizitätsmodul der Platte sorgen dafür, daß bei Änderung des arteriellen Druckes die Arterienwand entspannt bleibt.Die geringen druckproportionalen Auslenkungen des Mittelpunktes der Plexiglasplatte werden über einen Transducer in druckproportionale Stromänderungen genügender Stärke umgewandelt, die unverändert mit einem schnellschwingendem Spiegelgalvanometer registriert werden können. Die Aufzeichnungen sind daher amplituden- und phasengetreu.Mit 2 Textabbildungen     

Reduction in extracellular muscle volume increases heart rate and blood pressure response to isometric exercise

Summary To investigate the effect of local dehydration on heart rate and blood pressure during static exercise, six healthy male subjects performed exercise of the calf muscles with different extracellular volumes of the working muscles. Exercise consisted of 5 min of static calf muscle contractions at about 10% of maximal voluntary contraction. The body position during exercise was identical in all tests, i.e. supine with the knee joint 90° flexed. During a 25-min pre-exercise period three different protocols were employed to manipulate the calf volume. In test A the subjects rested in the exercise position; in test B the body position was the same as in A but calf volumes were increased by venous congestion [cuffs inflated to 10.67 kPa (80 mmHg)]; in test C the calf volumes were decreased by lifting the calves about 40 cm above heart level with the subjects supine. To clamp the changed calf volumes in tests B and C, cuffs were inflated to 300 mmHg 5 min before the onset of exercise. This occlusion was maintained for 1 min after the termination of exercise. Compared to tests A and B, the reduced volume of test C led to significant increases in heart rate and blood pressure during exercise. Oxygen uptake did not exceed resting levels in tests B and C until the cuffs were deflated, indicating that only calf muscles contributed to the neurogenic peripheral drive. It is concluded that extracellular muscle volume plays a significant role in adjusting heart rate and blood pressure during static exercise.     

Force kinetics and oxygen consumption during bicycle ergometer work in racing cyclists and reference-group

Summary The forces acting on the right crank of a bicycle ergometer were measured in 18 male subjects (6 racing cyclists, 8 students of physical education, 4 long distance runners) during an incremental exercise test. Oxygen consumption ( ) was simultaneously determined by means of a breath-by-breath method.Differences in peak values of the typical force record might indicate a different force distribution during each cranking cycle. When compared to the reference group, the racing cyclists showed peak values that were significantly lower at all levels of work load. Oxygen consumption during the initial 20 min of the test was found to be significantly lower in the cyclist group (cyclists: 37.2±3.2 l, reference group: 41.1±3.9 l). These results suggest that a different force distribution during a crank revolution might lead to an improved gross efficiency in the cyclist group. The findings might be due to different fractions of ST-fibres in the exercising muscle.     

Photographie des Streulichtes auf der Netzhaut

Zusammenfassung Es wird gezeigt, daß man durch Augenhintergrundphotographie den Streulichthof, der die Abbildung eines Lichtpunktes auf der Retina umgibt, auf Film sichtbar machen kann.Die erforderlichen Geräte wurden aus Mitteln eines Forschungsauftrages des Bundesverkehrsministeriums beschafft. Den Perutz-Werken, München, wird für die kostenlose Überlassung des Aufnahmematerials gedankt.     

Horizontal transfer of chloroplast genomes between plant species

The genomes of DNA-containing cell organelles (mitochondria, chloroplasts) can be laterally transmitted between organisms, a process known as organelle capture. Organelle capture often occurs in the absence of detectable nuclear introgression, and the capture mechanism is unknown. Here, we have considered horizontal genome transfer across natural grafts as a mechanism underlying chloroplast capture in plants. By grafting sexually incompatible species, we show that complete chloroplast genomes can travel across the graft junction from one species into another. We demonstrate that, consistent with reported phylogenetic evidence, replacement of the resident plastid genome by the alien genome occurs in the absence of intergenomic recombination. Our results provide a plausible mechanism for organelle capture in plants and suggest natural grafting as a path for horizontal gene and genome transfer between sexually incompatible species.