Effects of lateral fluid percussion injury on cholinergic markers in the newborn piglet brain.

Traumatic brain injury is a leading cause of death and disability in children. Studies using adult animal models showed alterations of the central cholinergic neurotransmission as a result of trauma. However, there is a lack of knowledge about consequences of brain trauma on cholinergic function in the immature brain. It is hypothesized that trauma affects the relative acetylcholine esterase activity and causes a loss of cholinergic neurons in the immature brain. Severe fluid percussion trauma (FP-TBI, 3.8+/-0.3atm) was induced in 15 female newborn piglets, monitored for 6h and compared with 12 control animals. The hemispheres ipsilateral to FP-TBI obtained from seven piglets were used for acetylcholine esterase histochemistry on frozen sagittal slices, while regional cerebral blood flow and oxygen availability was determined in the remaining eight FP-TBI animals. Post-fixed slices were immunohistochemically labelled for choline acetyltransferase as well as for low-affinity neurotrophin receptor in order to characterize cholinergic neurons in the basal forebrain. Regional cerebral blood flow and brain oxygen availability were reduced during the first 2h after FP-TBI (P<0.05). In addition, acetylcholine esterase activity was significantly increased in the neocortex, basal forebrain, hypothalamus and medulla after trauma (P<0.05), whereas the number of choline acetyltransferase and low-affinity neurotrophin receptor positive cells in the basal forebrain were unaffected by the injury. Thus, traumatic brain injury evoked an increased relative activity of the acetylcholine esterase in the immature brain early after injury, without loss of cholinergic neurons in the basal forebrain. These changes may contribute to developmental impairments after immature traumatic brain injury.

[Optimisation and establishing of serological methods for the potency testing of immunglobulins against Clostridium tetani-toxin]

The quality control of human tetanus immunglobulin requires animal experiments according to European Pharmacopoeia monograph 398. The potency estimation has to be done in a toxin neutralisation test in mice (MNT) or guinea pigs. Immunoassays could also be used if they show a suitable sensitivity and specificity. The first results of our study verify that an indirect enzyme linked immunosorbent assay (ELISA), a rocket immunelectrophoresis (RIE) and a toxin binding inhibition test (ToBI) could be used as serological alternativ methods to the MNT. Studies on the reproducibility of the in vitro methods resulted inter-assay coefficients of variation between 2 and 27%. The ELISA is more sensitive (limit of detectability: 0,005 IE/ml) than the ToBI (0,04 IE/ml) and the RIE (5 IE/ml). The transferability of the ELISA to other labs is proofed. The transferability of the RIE and the ToBI will be tested in the near future.