The jumping mechanism of Xenopsylla cheopis. III. Execution of the jump and activity

The flea's hind legs are the chief source of jumping power, but in species which execute large jumps, take-off is accelerated by elastic energy released from a resilin pad (homologous with the wing hinge ligaments of flying insects) situated in the pleural arch. A central click mechanism, operated by a rapid twitch of the trochanteral depressor (the starter muscle), synchronizes the separate sources of energy which power the jump. Ciné photos confirm the morphological evidence that the flea takes off from the trochanters, not the tarsi. The loss of wings, associated with lateral compression of the body and the shortening of the pleural ridge (which thus lowers the position of the pleural arch) together with modifications of the direct and indirect flight muscles, are some of the main morphological features associated with the change from a flying to a saltatorial mode of progression. The flea's take-off basically resembles that of other Panorpoid insects (Diptera, Mecoptera, etc.). The release of elastic energy from the pleural arch is a system by which the force used to move the wings of flying insects is rapidly fed back into the legs and adds power to the jump.

Uptake of 125I albumin by the endothelial surface of the isolated dog common carotid artery: effect of certain physical factors and metabolic inhibitors

A study has been made, under transient conditions, of the uptake of 125I albumin by the endothelial surface of isolated dog carotid arteries. Effective rate constants were determined and the apparent activation energy was calculated to be about 13 kcal/mol in the range 25-37 degrees C. Label uptake was not significantly altered by the presence of 1 mmol/1 potassium cyanide or 10 mmol/1 iodoacetate in the incubating medium, or by the absence of substrate from it, consistent with the process being primarily passive. It appeared that the label entered the wall mainly by other routes than the endothelial inter-cell clefts.

Antral function in duodenal ulcer. The gastric secretion of acid, chloride and pepsin in response to antral stimuli and to insulin and maximal histamine stimulation in duodenal ulcer and controls

A dye-dilution technique is used to compare the concentration and output of acid, chloride and pepsin in duodenal ulcer patients and controls following stimulation of the antrum with alcohol, sodium bicarbonate and peptone with the response to insulin hypoglycaemia and maximal histamine stimulation.

The mean secretory rate was higher in response to all the stimuli in duodenal ulcer patients except to sodium bicarbonate.

Following antral stimulation by peptone and sodium bicarbonate the acid and chloride concentrations rose to very high levels. The mean outputs were the same as those following maximal histamine stimulation although there were wide individual variations. There was no difference between duodenal ulcer patients and controls. The ‘neutral chloride’ concentration was much less than in the other phases.

The basal secretion and the secretions in response to insulin and histamine stimulation showed higher concentrations, as well as higher outputs of acid and chloride in duodenal ulcer patients.

Pepsin concentration in response to the various stimuli showed no difference between duodenal ulcer patients and controls and the pepsin output reflected the changes in secretory volume.