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Human traumatic brain injury (TBI) is ideally suited for investigation of the kinetics of human microglial cell activation as the onset of lesion formation is precisely defined. The present study provides evidence of a distinct delay in macrophage/microglia response following TBI. Eighteen brains of patients who had survived TBI for 1 h to 6 months were analysed by immunohistology. Samples of contusional and non-contusional areas were studied using antibodies directed against antigens of microglia/ macrophages [major histocompatibility complex class II, CD4, interleukin (IL)-16, macrophage-related protein (MRP) 8 and MRP14]. IL-16, a natural ligand to CD4, was expressed constitutively by numerous microglial cells in all cases throughout the brain. CD4 could be detected regularly on perivascular cells. MRP8 and MRP14, which are only expressed on activated macrophages and microglial cells, could be detected only within brains with a survival time of more than 72 h post TBI. In addition, proliferation of microglia detected by MIB-1 was not present until 72 h. This delayed expression of the activation markers MRP8 and MRP14 and the proliferation marker MIB-1 is comparable to experimental closed head injuries but strictly different from acute activation found in ischemic brains.

Interchange of ethanol between the compartments of the body results from transport in a linked convection-diffusion system. This system can be described mathematically by dividing up the cardiac output in a shunt flow and a flow immediately mixed into the integrated solvent volume of the body. Experimental measurement shows that the ratio of shunt flow and mixing flow is nearly 1:1. Furthermore, this division allows a calculation of the arterial ethanol concentration from the venous one and an estimation of the quantity of ethanol diffused into the tissue volume.

To verify a presumed interaction between shockwaves arisen by impacts of high velocity projectiles and nervous tissue an electrophysiological experiment is performed with the following results: In peripheral nerves regular compound action potentials (CAPs) are provoked by shockwaves the amplitudes of which are increased corresponding to the pressure intensity of the shockwaves. The nerve shows no electrical activity below a certain pressure threshold (0.75 bar). Saturation of the CAP amplitude occurs beyond a pressure limit of 8 bar.