1001–24 Local Delivery of Urokinase to Porcine Coronary Arteries Using the Localmed Infusion Sleeve

Local Delivery of thrombolytic agents may reduce thrombus formation after balloon angioplasty. The Localmed Infusion Sleeve enables localized infusion of urokinase to be performed at the time of balloon angioplasty without the need for catheter exchange.MethodsBalloon angioplasty was performed on 13 coronary arteries of 5 pigs at 4 atmospheres with a balloon to artery ratio of approximately 1.1 to 1. After angioplasty the Infusion Sleeve was advanced over the dilatation balloon and the balloon was reinflated to 2 atmospheres to appose the sleeve to the vessel wall. 50,000 Units (8 cc) of 123l-urokinase was infused through the microperforations in the sleeve for 10 seconds by a computer controlled pump. The coronaries were then excised and counted in a gamma counter.ResultsConclusions(1) The Localmed Infusion Sleeve enables drug infusion to be uncoupled from balloon dilatation. (2) Successful delivery of Urokinase to the vessel wall may be achieved using this device without the need for catheter exchange. (3) Persistence of urokinase within the vessel wall occurs after local delivery

Absence of shock-elicited aggression in pigeons

Two pigeons that attacked a taxidermically prepared target pigeon during a schedule of positive reinforcement for key pecking, and two that did not, were shocked through implanted electrodes in the presence of the target. Shock intensities of 2 and 4 mA, durations of 0.1 and 1.3 sec, and frequencies of 2, 6, 20, and 35 per minute were delivered across 16 sessions with 180 shocks per session. No pigeon attacked the target; one pecked the shockplug on its back. The two pigeons that had not attacked during the positive reinforcement schedules were conditioned to peck the target for food reinforcement before another 16 sessions of shock. No attack was observed in these shock sessions. During subsequent positive reinforcement of key pecking, the target was attacked by the two pigeons that had originally attacked and by one that had not. Absence of shock-elicited attack in these pigeons may be related to the parameters of the experiment or may be yet another instance of the absence of shock-elicited attack in the class Aves. At least under the present conditions, it was not possible to predict the level of attack during electric shock from the level of attack during schedules of positive reinforcement for key pecking

Lever attacking by rats during free-operant avoidance

Rats pressed a lever to avoid shock on a free-operant avoidance schedule. Some subjects were also exposed to extinction in which the response-shock contingency was eliminated while the shock-shock contingency remained in effect. A specially constructed lever was used that registered not only presses, but also biting attacks on the lever. Throughout various phases of the study, shocks often elicited lever biting as well as post-shock responding. The results suggested that shock-elicited attacks that are forceful enough to activate the operandum might account for some of the responding that occurs in experiments on free-operant avoidance behavior. In particular, shock-elicited operandum attacking might account for post-shock response bursting during free-operant avoidance and the extreme persistence of responding sometimes noted when shocks are delivered during the extinction of avoidance behavior. To the extent that this is true, these phenomena should not be characterized as operant behavior in interpreting the results of experiments on free operant avoidance

Response reduction through the superimposition of continuous reinforcement: a systematic replication.

Prior clinical research suggests that superimposition and subsequent removal of a schedule of continuous reinforcement (CRF) may be a viable rate-decreasing procedure in that an extinction-like condition is arranged. The arrangement of similar conditions in the laboratory, however, resulted in the quick recovery of baseline rates. Lever-pressing patterns of eight male rats maintained by different schedules of variable-ratio and variable-interval food reinforcement were examined in an A-B-A experimental design of CRF food superimposition and removal. Responding was substantially reduced during the superimposition of CRF. Upon removal of the superimposed schedule, responding quickly approached presuperimposition baseline rates

Negative reinforcement in applied behavior analysis: an emerging technology.

Although the effects of negative reinforcement on human behavior have been studied for a number of years, a comprehensive body of applied research does not exist at this time. This article describes three aspects of negative reinforcement as it relates to applied behavior analysis: behavior acquired or maintained through negative reinforcement, the treatment of negatively reinforced behavior, and negative reinforcement as therapy. A consideration of research currently being done in these areas suggests the emergence of an applied technology on negative reinforcement

A Review of Reinforcement Control Procedures

A demonstration of the effects of reinforcement requires comparison of response rates in the presence of a contingency with those in another condition that controls for the influence of extraneous variables. We describe several control conditions that have been used in evaluating the effects of positive and negative reinforcement. The methodological rigor and practical utility of each type of control condition are discussed, and recommendations for the use of these conditions are presented

Experimental analysis and extinction of self-injurious escape behavior.

Three studies are presented in which environmental correlates of self-injurious behavior were systematically examined and later used as the basis for treatment. In Study 1, 7 developmentally disabled subjects were exposed to a series of conditions designed to identify factors that maintain self-injurious behavior: attention contingent on self-injurious behavior (positive reinforcement), escape from or avoidance of demands contingent on self-injurious behaviour (negative reinforcement), alone (automatic reinforcement), and play (control). Results of a multielement design showed that each subject's self-injurious behavior occurred more frequently in the demand condition, suggesting that the behavior served an avoidance or escape function. Six of the 7 subjects participated in Study 2. During educational sessions, "escape extinction" was applied as treatment for their self-injurious behavior in a multiple baseline across subjects design. Results showed noticeable reduction or elimination of self-injurious behavior for each subject and an increase in compliance with instructions in all subjects for whom compliance data were taken. The 7th subject, whose self-injurious behavior during Study 1 occurred in response to medical demands (i.e., physical examinations), participated in Study 3. Treatment was comprised of extinction, as in Study 2, plus reinforcement for tolerance of the examination procedure, and was evaluated in a multiple baseline across settings design. Results showed that the treatment was successful in eliminating self-injurious behavior and that its effects transferred across eight new therapists and three physicians. General implications for the design, interpretation, and uses of assessment studies are discussed