Showing papers by "Danube University Krems published in 1999"

Fractionated Plasma Separation and Adsorption System: A Novel System for Blood Purification to Remove Albumin Bound Substances

Abstract: The removal of albumin bound substances has gained increasing interest in different diseases, especially in acute and chronic liver disease. Therefore, a new system, the fractionated plasma separation and adsorption (FPSA) system, was developed based on combined membrane and adsorbent blood purification techniques. The most important contribution to the FPSA system was the development of a new polysulfone hollow-fiber filter, which is characterized by a sieving coefficient of 0.89 for human serum albumin (HSA) but only of 0.17 for fibrinogen, and 0 (zero) for IgM immunoglobulins. Using a closed filtrate circuit connected to the new polysulfone filter which integrates 1 or 2 adsorption columns and also a high flux dialyzer adapted to a dialysis machine, the FPSA system opens excellent possibilities for the relatively specific removal of albumin bound substances from the blood such as albumin bound bilirubin or even tryptophan. In comparison to other systems (for example, the Molecular Adsorbent Recirculating System [MARS] and albumin dialysis systems), the FPSA system enables much higher elimination of strongly bound albumin substances. The first clinical investigations have recently started based on a modified dialysis machine designed with all necessary safety measures.

Microspheres based detoxification system: in vitro study and mathematical estimation of filter performance.

Abstract: Because of the closed plasma (secondary) circuit in the Microspheres based Detoxification System (MDS), a convective blood purification system, the same amount of filtrated plasma is backfiltrated into the blood circuit. Therefore, there is no direct way to determine the ultrafiltrate production rate, which is an important factor of efficiency. The only possible way to estimate the filtration properties of the filter is to consider pressure values. In this study the pressure distribution in the filter was investigated in vitro. To explain the results and to calculate inaccessible parameters, a mathematical model was established which also considered the asymmetric behaviour of the filter membrane. The result was a linear pressure gradient, agreement with the measurements was reasonably good (calculated primary pressure loss differs <13% from measured value when using mean measured filter resistance as model parameter). Linear pressure distribution offers the possibility of easily calculating the filtration length, a parameter which can be used to estimate the filter condition. The comparison between calculated filtration and backfiltration rates offers an instrument of control for these values.

In Vitro Cell Culture Systems as the Basis for an Extracorporeal Blood Purification Strategy In Multiorgan Failure Treatment

Abstract: Multiorgan failure (MOF) based on septic processes is very common but prognostically an extremely severe disease that has to be treated exclusively under intensive care conditions. Extracorporeal blood purification (ECBP) using specific and efficient systems such as the microspheres based detoxification system (MDS) (Artif Organs 1996;20:420) could improve significantly the situation of MOF in terms of the efficient removal of endotoxins as well as key mediators such as tumor necrosis factor alpha (TNF alpha). The purpose of the study was to test the effectiveness of endotoxin and cytokine removal to blunt cellular response. In terms of the in vitro principle methodology, isolated peripheral blood mononuclear cells (PBMC) were incubated with endotoxins and a selective endotoxin adsorbent, which was added at various times (immediately or 30, 60, 120, 240, or 360 min) after the onset of incubation. TNF alpha release of monocytes was measured following a standard procedure after 20 h. Human TNF alpha was incubated with cultured human endothelial cells with and without a specific TNF alpha adsorbent (polyclonal antibodies coated on polystyrene particles). The results showed that after the initial addition of endotoxins, the activation of monocytes can be stopped within 120 min by addition of endotoxin adsorbents. In addition, specific TNF alpha adsorbents are able to prevent intercellular adhesion molecule 1 (ICAM-1) expression of endothelial cells, therefore avoiding activation of endothelial cells. In conclusion, cell culture models are suitable to simulate cell interaction in MOF. Specific adsorbents are able to reduce or block pathophysiologically relevant cell interactions, and the time frame for effective ECBP seems to be very short, and therefore, efficiency must be high.