Swing phase control with knee friction in juvenile amputees.

Above-knee amputees have a slower than normal walking velocity. In conventional prostheses the solution has been to apply knee friction to attempt to match the cadence of the prosthetic limb to the sound limb. Using kinematic data, we investigated the effect of variable knee friction on the swing phase of gait in juvenile amputees. The subjects were instructed to walk at a comfortable pace and were tested repeatedly with varying amounts of knee friction. We found that the excursion of the prosthetic shank as measured by knee range of motion was altered by changing the amount of knee friction. The period of the prosthetic shank remained constant when measured as a physical pendulum and when measured dynamically during gait. Therefore, knee friction is an effective means of providing the amputee with a more symmetrical appearing gait by matching the heel rise of the prosthetic limb to the sound limb. It is not an effective means, however, of matching the cadence of the prosthetic limb to the sound limb.

Phospholipids associated with vitamin C in experimental atherosclerosis.

The favourable action of phospholipids and of Vitamin C in reverting the process of atherogenesis, already repeatedly described in the literature, was explored by the authors in applying an association of these two substances in experimental atherosclerosis. The obtained results not only confirm, once again, the prophylactic and therapeutic activity of phospholipids and vitamin C, but also demonstrate that these components, when associated, lead to much better results in the prevention and resolution of atheromatous plaques provoked in rabbits by cholesterol-feeding.

An infallible method for producing ascitic fluid from solid tumours.

Notwithstanding all precautions, the methods usually applied for the transformation of solid tumours into the ascitic form, frequently fail. This must certainly be ascribed to the still existing, considerably high intercellular adhesion forces despite the fact that cancer cells generally show lack of adhesiveness due to their higher electrical charge in comparison with normal cells. Hagmar recently stipulated that particularly anionic detergents increase the negative surface charge of tumour cells, while cationic detergents drastically reduce or even reverse this charge. A series of comparative experiments were undertaken by us in order to study the influence of anionic, nonionic and amphoteric detergents on the production of ascitic fluid from macerates of Yoshida sarcoma and fibrosarcoma BUSP. This latter tumour was produced and maintained in our laboratory and resisted to all our attempts to produce the ascitic form. Heparin, in concentrations of 0,2, 0,4 and 1,0 mg/ml, was used as an example of an anionic detergent; Pluronic F-68 and phosphatidylcholine, both in concentrations of 1, 2, and 5 mg/ml, represent a nonionic and an amphoteric detergent, respectively. The obtained results clearly show a most favourable action of the applied surfactants: whereas the controls, in which the detergents were not applied, failed to produce ascitic fluid in, sometimes, considerable percentages (up to 100% in the case of BUSP) of the treated animals, not a single animal remained free of ascite when the injected macerate was pre-treated with the emulsifier. It should here be mentioned, however, that heparin in the highest concentration applied (1 mg/ml) caused lysis of the tumour cells impeding, thus, whatever formations of ascitic fluid.

Growth inhibition of tumour implants by associated surface active agents.

Whereas dilute solutions of surface active agents modify the properties of cell membranes, particularly in relation to their electrical behaviour, moderate and strong solutions provoke more serious structural damage of the membrane, leading to an increase of its permeability and, finally, to cytolysis. These phenomena have inspired some authors to apply detergents as possible cancer chemotherapeuticals so far, however, with only poor results. The disintegrating effect of tumour emboli into single cells by certain detergents, and the ingenious discovery that the mutual adhesiveness between cancer cells is much less than between normal cells, have led the present authors to investigate the action of some biological surface active agents, alone as well as in some of their associations on the "take" of Yoshida sarcoma implants. Certain associations showed, in contradistinction to the separately applied components, surprisingly favourable activity. It could be established that a correlation actually exists between inhibitory effect and surface activity.