Antibody production in rats following ocular-topical or gastrointestinal immunization: kinetics of local and systemic antibody production.

The kinetics of the anti-DNP antibody response to DNP-pneumococcus appearing in tears and bile (IgA) and serum (IgM and IgG) was examined in rats after the application of antigen either via the ocular-topical (OT) or gastrointestinal (GI) routes. It was found that IgA responses were obtained each time in tears after either OT or GI antigen doses given monthly for three months, but that the OT route gave rise to consistently higher tear antibody titres than the GI route of immunization. Comparable IgA responses were found in bile using either route. In serum a small primary IgM response was consistently obtained but the main antibody found was IgG, the timing and degree of response being about the same for both routes. When the adjuvants Avridine in liposomes or MTP-PE were added along with the antigen it was found that with either immunization route, the tear IgA response was much reduced compared to when no adjuvant was used; the serum IgG response was marginally increased when adjuvant was added. The effects of binding anti-DNP monoclonal IgA or IgG1 to antigen before immunizing via the OT route was also studied. It was found that the presence of immunoglobulin of either isotype in the complex caused an increase in the serum IgG response, but that the tear IgA response was diminished in rats receiving IgA/antigen complexes compared with those receiving IgG/antigen or antigen alone.

A kinetic analysis of sprinting.

To investigate the kinetics of sprinting, 15 male runners were filmed during a maximal effort sprint. The results were digitized, computer processed, and analyzed with interest focused on the muscle moment patterns about the ankle, knee, hip, shoulder, and elbow. The moments about the ankle consisted of minimal activity during the air phase to plantar flexor dominance during the ground phase. At the knee, the pattern demonstrated extensor to flexor dominance during the air phase, followed by flexor to extensor dominance during the ground phase. The hip moment pattern was composed of flexor to extensor activity during the air phase, then extensor to flexor dominance during ground contact. The magnitude of the lower limb joints indicated maximum exertion, with the highest values occurring during eccentric contraction. The greatest effort was generated by the hip extensor/knee flexor muscle group during the initial portion of ground contact, which corresponds with the area of greatest sprint injury. The angular force generation about the shoulder consisted of alternate flexor to extensor activity (extensor to flexor activity about the opposite shoulder), while the elbow activity was dominated by the flexors, with only brief extensor supremacy. The relatively small upper limb muscle moments seem to relegate the arms to the simple role of maintaining balance.

A biomechanical analysis of the Olympic-style flatwater kayak stroke.

To investigate the biomechanics of flatwater kayaking, the technique of nine Olympic caliber K-1 paddlers was analyzed using cinematographic and computer procedures. Results indicated that, during paddle-water contact, the horizontal arm action was one of push-then-pull with the push coming from the arm farthest from the water (thrust segments) followed by the pull coming from the arm closest to the water (draw segments). During this action, the center of paddle rotation shifted up the paddle shaft as the stroke progressed, which increased the time the paddle was in the power phase of the stroke. The horizontal movement patterns of the individual segments indicated that the push was accomplished by an integrated movement of the thrust wrist and elbow, with minimal shoulder involvement. Subsequently, the pull was accomplished by an integrated movement of the draw wrist, elbow, shoulder, as well as the thrust shoulder. During the latter stages of water contact, since the performers were unable to generate additional useful power, the paddle was rapidly withdrawn to avoid dragging. Subject stability in the frontal plane was maintained by shifting the body mass toward the water contact side at paddle entry and away from it at exit. This action opposed the vertical forces produced as a by-product of the stroke. The final outcome of this stroke technique was the maintenance of the body center of gravity velocity while the boat oscillated under the performer.

The Jones fracture revisited.

Twenty-two patients with twenty-three fractures of the proximal part of the diaphysis of the fifth metatarsal, an injury originally described by Jones, are reported. The average follow-up was 3.5 years. Delayed union occurred in twelve (66.7 per cent) of eighteen patients treated conservatively. Four patients were operated on within two weeks of injury. The clinical picture in nine of the twenty-two patients suggested that the injury was a stress fracture. Force-platform analysis in eleven cases confirmed that the injury results from vertical and mediolateral forces concentrated over the fifth metatarsal and that it is not caused by inversion. Thirteen of the twenty-three fractures were in young athletes, often occurring during training and causing significant disability. In this group of patients, and in a select number of recreational athletes and non-athletes with delayed union, intramedullary screw fixation of the fracture is advised.