The influence of the counterfort while ballistic testing using gelatine blocks.

In wound ballistic research, gelatine blocks of various dimensions are used depending on the simulated anatomical region. When relatively small blocks are used as substitute for a head, problems with regard to the expansion of the gelatine block could arise. The study was conducted to analyse the influence of the material the gelatine block is placed upon. Thirty-six shots were performed on 12 cm gelatine cubes doped with thin foil bags containing acrylic paint. Eighteen blocks each were placed on a rigid table or on a synthetic sponge of 5 cm height. Deforming bullets with different kinetic energies were fired from distance and recorded by a high-speed video camera. Subsequently, the gelatine cubes were cut into 1 cm thick slices which were scanned using a flatbed scanner. Cracks in the gelatine were analysed by measuring the longest crack, Fackler's wound profile and the polygon (perimeter and area) outlining the ends of the cracks. The energy dissipated ranged from 153 to 707 J. For moderate energy transfer, no significant influence of the sustaining material was discerned. With increasing dissipated energy, the sponge was compressed correspondingly, and the cracks were longer than in gelatine blocks which had been placed on a table. High-speed video revealed a loss of symmetry and a flattened inferior margin of the temporary cavity with energies superior to approx. Two hundred Joules when the blocks were placed on a rigid platform. However, 12 cm gelatine cubes showed material limits by a non-linear response when more than 400 J were dissipated for both rigid and elastic sustainment. In conclusion, the smaller the gelatine blocks and the greater the energy transfers, the more important it is to take into account the counterfort of the sustaining material.

Antibody-mediated depletion of immunosuppressive factors from ovarian carcinoma-associated ascites for investigation of paracrine versus autocrine effects.

Many studies seek to explore the impact of extrinsic soluble factors present in serum, interstitial fluids or cell-conditioned media on cells in vitro. A convenient approach to elucidate the effects of a particular factor is its selective neutralization. However, intrinsic production of soluble factors such as cytokines by the cultured cells is common and can have an impact via autocrine mechanisms. The addition of cytokine-specific neutralizing antibodies leads to neutralization of the targeted factors irrespective of their source and affects paracrine and autocrine effects alike. Thus, neutralization assays are not suitable to irrevocably demonstrate that the examined factors exert their effect via a paracrine mechanism. We were interested in investigating the impact of immunosuppressive factors present in ovarian carcinoma-associated ascites by dissecting paracrine versus autocrine effects of interleukin 10 (IL-10) and prostaglandin E2 (PGE2) on the activation of monocyte-derived dendritic cells (DC). We explored several methods of depletion based on introduction of the neutralizing antibodies bound to beads. Here we describe the pitfalls of the investigated depletion approaches and show the importance of monitoring the presence of residual neutralizing antibodies in the sample upon depletion, which impacts on the suitability of the approach to distinguish paracrine from autocrine effects. Only one of three investigated approaches showed no dislocation of neutralizing antibody from the beads into the sample. This method, which is based on covalently linking antibody to magnetic beads harbouring a reactive group allowed for the complete removal of the investigated factors from ascites and represents an elegant tool to elucidate immunoregulatory or -stimulatory cytokine networks in considerably more depth than the use of neutralizing antibodies in cell cultures alone can contribute.