Morphophysiologic characterization of peripheral neuropathy in zinc-deficient guinea pigs.

Zinc-deficient guinea pigs develop a peripheral neuropathy characterized by abnormal posture and gait, hyperesthesia, slowed motor nerve conduction velocity (MNCV), and decreased sciatic nerve Na,K-ATPase activity. This study was designed to further investigate longitudinally the morphophysiologic features of the neuropathy. Weanling guinea pigs were fed a low-zinc (<1 mg/kg) diet ad libitum (-ZnAL), an adequate-zinc (100 mg/kg) diet ad libitum (+ZnAL), or the adequate diet restricted in intake ((+ZnRF). Electrophysiologic, morphologic, and biochemical parameters of peripheral nerves were examined at 2.5, 4.0, and 5.5 weeks. Serum zinc was significantly lower by 2.5 weeks and growth rate reduced by 4 weeks in -ZnAL animals. Postural abnormalities were first obvious at 4 weeks, although MNCVs were significantly slower in zinc-deficient animals at all time intervals. The conduction of sensory impulses, as measured by spinal cord somatosensory evoked potentials (sSSEP), was significantly slower in the -ZnAL animals at 5.5 weeks. Examination of teased preparations and histologic sections of sciatic nerves at 5.5 weeks revealed no degenerative lesions or differences in density of myelinated fibers (MF). The size frequency distribution of MF in all groups was unimodal, with a trend toward smaller myelinated nerve fibers in -ZnAL and +ZnRF animals. Sciatic nerve Na,K-ATPase activity in the -ZnAL animals was significantly reduced after 4 weeks of zinc deprivation. At 5.5 weeks, nerve concentrations of myo-inositol, glucose, fructose, and sorbitol were significantly decreased in -ZnAL animals compared with the +ZnRF and +ZnAL controls. The peripheral neuropathy associated with acute zinc deficiency is a parenchymatous axonal disorder characterized by slowed motor and sensory nerve impulse conduction and reduction in nerve Na,K-ATPase activity and nerve concentrations of simple sugars and their metabolites.

Evaluation of a subcutaneously implanted chamber for antibody production in rabbits.

Polyclonal antibody production in subcutaneous chambers was compared to traditional antibody production methods in rabbits. The chamber, a sterilized plastic wiffle golf ball that had been surgically implanted in the subcutis of the thoracic region, was immunized via a percutaneous injection of antigen into the core of the ball through one of the perforations in the chamber wall. Rabbits bearing chambers were immunized on the same schedule and with the same concentrations of antigens as were provided the adjuvant injected rabbits. Fluid volumes of 12 to 22 ml could be removed from each chamber at weekly intervals. Chamber antibody to specific microbial antigens was equal to or better than serum antibody produced to the same antigens with Freund's or acrylamide adjuvants. The comfort of the rabbit, the ease in chamber immunization, and the recovery of high titer antibody in large volumes make the subcutaneous chamber an attractive method for polyclonal antibody production.