In vivo neutrophil sequestration within lungs of humans is determined by in vitro "filterability".

Neutrophils are normally delayed in transit through the lung microcirculation, relative to the passage of erythrocytes. This sequestration contributes to a pulmonary pool of neutrophils that may relate to the relative inability of neutrophils to deform compared with erythrocytes when in transit in the pulmonary capillaries. A micropore membrane was used to model the human pulmonary microcirculation, in which cell deformability was measured as the pressure developed during filtration of the cells through the membrane at a constant flow. We demonstrated a significant correlation between in vitro deformability and in vivo lung sequestration of indium-111-labeled neutrophils in 10 normal subjects (r = 0.69, P less than 0.02). In eight patients with stable chronic obstructive pulmonary disease, this relationship was not significant (r = -0.2, P greater than 0.05). Furthermore, in a subject with microscopic pulmonary telangiectasia known to allow significant passage of 30-microns microspheres, neutrophils passed through the lungs without delay. Moreover, neutrophils from patients studied acutely with an exacerbation of chronic obstructive pulmonary disease were temporarily less deformable (P less than 0.01). These studies confirm that cell deformability is an important determinant of the normal neutrophil sequestration within the lungs. Changes in cell deformability may alter the extent of this sequestration.     

Zur entomostraken-fauna des seeburger sees

Ohne Zusammenfassung     

IX. und X. Bericht der Vogelwarte der Staatl. Biologischen Anstalt Helgoland. (1924 und 1925.)

Ohne Zusammenfassung     

The energetics of feeding strikes in larval carp, Cyprinus carpio

The prey intake of larval carp is described from high-speed (200–1250 frames s⁻¹) films with synchronous lateral and ventral views. Even in first-feeding carp larvae, the operculars are functional in sealing effectively the opercular slit until the moment of prey intake, and the maxillaries close off the corners of the mouth, preventing leak flow. In reducing the distance between larva and prey during attack, the relative importance of sucking the prey towards the mouth and swimming forward is variable; overall they are about equally important. The volume and the velocity of the water sucked into the mouth cavity during prey uptake are calculated. The energy costs of suction, i.e., accelerating the water sucked into the mouth cavity, during prey intake are estimated from these values. The energy costs of suction and swimming are in the same order of magnitude. Together they form only a fraction of 1% of the energetic content of the prey, so considerations about energy expenditure seem unimportant in a strategy to optimize the prey attack. During searching, however, they will be important. Power requirements during attack may also be important.