Effects of local extraneural application of diphtheria toxin on the sciatic nerves of normal and protein deprived rats

An outbreak of diphtheria among Swedish alcoholics

After 25 years without any indigenous cases of diphtheria in Sweden, an outbreak occurred in the city of Göteborg, during 1984 to 1986. A group of alcoholics constituted the reservoir of Corynebacterium diphtheriae. The outbreak included 13 clinical cases and 65 carriers. The death-to-case ratio and the complication rate among the clinical cases was high, with three fatal cases and six patients developing reversible paralyses. The fatal cases had no history of previous immunization. The outbreak demonstrates the necessity of a good vaccination status to diphtheria, also in countries where the disease was thought to have been eradicated.

The influence of protein deprivation during development on amino acid incorporation into cerebral proteins

The incorporation of 3H-valine into protein of cerebrum, liver, and muscle was studied in rats fed a low protein diet. Animals, 15-50 days old, were used to cover the period during and after the most rapid phase of cerebral protein synthesis. The precursor was administered in doses resulting in brain concentrations of free valine in the 0.1-0.3 mM range. Two series of experiments were run and the injected dose varied for comparison of protein synthesis at different concentrations of precursor valine. By concomitant amino-acid analysis it was shown that the concentration of other amino-acids in the brain was not changed by the injected valine. The changes in the amino-acid pool with age in control rats were in agreement with previous findings. Only small alterations were seen in the amino acid pool as an effect of protein deprivation, the results being consistent with those of some previous reports. Uptake of valine into the brain appeared to be decreased only in 15-17-day-old protein-deprived rats. Valine incorporation into cerebral protein was decreased in the youngest age group but no effect was seen in older animals. Liver protein incorporation was slightly decreased by low protein diet but a marked reduction was observed for muscle protein. The changes in brain protein synthesis during normal development were in agreement with previous studies and differed qualitatively from those in liver and muscle.

Barriers and transport properties of the perineurium. An ultrastructural study with 125I-labeled albuminin and horseradish peroxidase in normal and protein-deprived rats

The permeability properties of the perineurium in sciatic nerves of 12-week-old rats were studied. The penetration of 125I-labeled albumin and horseradish peroxidase into the perineurium was investigated electronmicroscopically 10, 30, and 120 min after the local extraneural application of the tracers. The autoradiographic study included age-matched protein-deprived rats. It was concluded that the perineurium acted as a diffusion barrier but also permitted a slow passage of the macromolecules into the endoneurium. The result indicates that this penetration to some extent is due to vesicular transport across the perineurial cells. The significance of these barrier and transport properties of the perineurium is discussed. No obvious differences in perineurial permeability between normal and protein-deprived rats were obtained.