Pulsed radio frequency therapy of experimentally induced arthritis in ponies.

The effect of pulsed radio frequency therapy (PRFT) was evaluated on seven ponies with no arthritis and in 28 ponies in which arthritis was created using intra-articular amphotericin B to induce synovitis in the right middle carpal joint. The ponies were divided into five treatment and two control groups. Two levels of arthritis were created and two dosage levels of PRFT were evaluated. The effect of PRFT on arthritic and nonarthritic joints was measured by comparing synovial fluid parameters, the degree and duration of lameness, the range of carpal motion, and carpus circumference, for treated and untreated groups. Lesions seen radiographically, at gross pathology, and by histopathology were also compared between the treated and control groups. In the ponies with a mild form of induced arthritis, PRFT significantly (p less than 0.05) reduced the severity and duration of lameness, swelling of the carpus, and the severity of gross pathological and radiographic changes. In these ponies the synovial acid phosphatase levels were lower, the mucin clot quality was superior, and the synovial protein levels were lower for the ponies receiving PRFT as compared to the arthritic ponies receiving no treatment. A dose response effect was evident. In ponies with a slightly more severe form of arthritis, PRFT was evaluated at one dosage level. The treated ponies were significantly improved over the untreated ponies with respect to carpal range of motion, degree of lameness, carpus swelling, and radiographic lesions. No deleterious effects were noted when normal, PRFT treated, middle carpal joints were compared to contralateral untreated, normal joints. It was concluded that significant beneficial effects resulted when affected ponies were treated with PRFT.

Chronic recording from the His bundle of the awake dog.

The conventional catheter method for measuring specialized A-V nodal and His-ventricular conduction times in the intact dog heart precludes an unanesthetized control. This control is necessary for meaningful studies of the effect of drugs or drug-drug interactions on A-V conduction times. At right thoracotomy (halothane anesthesia), mongrel dogs had bipolar electrodes sutured to the epicardial surface of both atrial appendages, junctions of the sulcus terminalis with both vena cavae, and right ventricle. A unipolar needle electrode, referenced to a unipolar electrode on the ascending aorta, was inserted into the interatrial septum from the aortic root for recording the His bundle electrogram. After one to three weeks for stabilization, weekly measurements were made of A-V nodal conduction time (AVN) and His-ventricular conduction time (H-V) for up to 52 weeks (4 to 52 weeks). Mean values (13 dogs) for spontaneous cycle length, AVN and H-V conduction times were 477 +/- 25, 82 +/- 3, and 30 +/- 1 msec, respectively. Simultaneous recordings from catheter and implanted His bundle electrodes were made during changes in atrial paced rate (five dogs, pentobarbital anesthesia). Values for AVN and H-V conduction times from catheter or implanted electrodes were the same. AVN conduction time increased, H-V conduction time remained constant during increases in atrial rate. Atropine shortened and propranolol prolonged AVN conduction time in six unanesthetized, unsedated dogs; neither affected H-V conduction time. Histologic examination of electrode sites in two dogs at 43 and 52 weeks showed no evidence of damage to underlying myocardial recording sites. This preparation provides reproducible awake values for AVN and H-V conduction times, and hence a more meaningful control for pharmacologic investigations.

Rheumatoid arthritis: a two-axis goniometer to measure metacarpophalangeal laxity.

A 2-axis goniometer has been developed which accommodates the metacarpophalangeal (MCP) changes of rheumatoid arthritis and permits accurate measurement of laxity of the MCP joints. Measurements made with the instrument on 51 subjects with definite or classical rheumatoid arthritis showed high percentages of intrarater and interrater agreement for repeated trials. These results suggest that, following the methods outlined, the 2-axis goniometer can be used to obtain reliable objective measurements of MCP lateral mobility by 1 or more raters with a minimum of training.

An autoclavable electronic interface for germfree isolators.

An electronic interface was designed and fabricated for use with germfree isolators. It allows a variety of sensors or electrical instruments inside an isolator to be readily connected to monitoring or activating devices on the outside of an isolator. It was built into a 25 cm diameter cylinder whose open ends were loosely covered by an inner and outer connector panel. These two panels were wired together through an airtight dividing wall placed transversely across the middle of the cylinder. The interface was mounted in an entry port of a stainless steel isolator and steam sterilized with the isolator. It has proven to be a useful, contamination-free, durable device.