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Direct Adsorption (direct + adsorption)

Distribution by Scientific Domains

Medical Sciences	85%

Selected Abstracts

Ex Vivo Biocompatibility of Avidin-Agarose: A New Device for Direct Adsorption of Biotinylated Antibodies from Human Whole Blood

ARTIFICIAL ORGANS, Issue 9 2000
T. Bosch
Abstract: Radioimmunotherapy using radiolabeled antitumor antibodies (RAA) is limited by the toxicity of unbound antibodies in the circulation. Removal of excessive antibodies by affinity-adsorption could therefore allow the administration of increased dosages of RAA while decreasing their adverse effects. Recently, avidin-agarose (AA) minicolumns were used in animal experiments for the removal of biotinylated antibodies from whole blood exploiting the high affinity binding of biotin to avidin (pK 1015 M,1). This study was performed to evaluate the ex vivo biocompatibility of AA minicolumns with human blood. Ten ml AA minicolumns were perfused online ex vivo in the single pass mode with fresh blood from 8 healthy donors at a flow rate of 6.25 ml/min. The anticoagulation consisted of 0.5 IU heparin plus 0.0,2.1 mg citrate per ml of blood. In Part 1 of the study (40 min perfusion, n = 4), the optimal anticoagulation was found to be 0.5 IU heparin plus about 1 mg citrate per ml of blood. In Part 2 of the study, four 80 min test-runs were performed. No signs of hemolysis were found, and the thrombogenicity of the AA gel was negligible. Cell counts and column inlet pressures remained constant; toward the end of the 80 min test-runs, some activation of blood cells (elastase, ,-thromboglobulin), the complement system (C3a, C5a) and the plasmatic coagulation (thrombin-antithrombin complex) was detectable. A moderate initial bradykinin release rapidly subsided to very low levels. In summary, AA minicolumns showed good biocompatibility upon contact with human whole blood and merit further investigation in a closed-loop system for a potential application of direct tumor antibody removal by hemoperfusion. [source]

DALI Apheresis in Hyperlipidemic Patients: Biocompatibility, Efficacy, and Selectivity of Direct Adsorption of Lipoproteins from Whole Blood

ARTIFICIAL ORGANS, Issue 2 2000
T. Bosch
Abstract: Recently, the first apheresis technique for direct adsorption of low-density lipoprotein (LDL) and lipoprotein(a) [Lp(a)] from whole blood (DALI) was developed that does not require a prior plasma separation. That markedly simplifies the extracorporeal circuit. The aim of the present study was to test the acute biocompatibility, efficacy, and selectivity of DALI apheresis. In a prospective clinical study, 6 hypercholesterolemic patients suffering from angiographically proven atherosclerosis were treated 4 times each by DALI. 1.3 patient blood volumes were treated per session at blood flow rates of 60,80 ml/min using 750 or 1,000 ml of polyacrylate/polyacrylamide adsorber gel. The anticoagulation consisted of an initial heparin bolus followed by a citrate infusion. The sessions were clinically essentially uneventful. Mean corrected reductions of lipoproteins amounted to 65% for LDL-cholesterol, 54% for Lp(a), 28% for triglycerides, 1% for HDL-cholesterol, and 8% for fibrinogen. The selectivity of lipoprotein removal was high. Cell counts remained virtually unchanged and no signs of hemolysis or clotting were detected. Cell activation parameters elastase, ,-thromboglobulin, interleukin-1,, and IL-6 showed no significant increase. Complement activation was negligible. There was significant, but clinically asymptomatic, bradykinin activation in the adsorber with mean maxima of 12,000 pg/ml in the efferent line at 1,000 ml of treated blood volume. In conclusion, DALI proved to be safe, selective, and efficient for the adsorption of LDL-C and Lp(a), which simplifies substantially the extracorporeal therapy in hypercholesterolemic patients. [source]

Efficacy and safety of DALI LDL-apheresis at high blood flow rates: A prospective multicenter study

JOURNAL OF CLINICAL APHERESIS, Issue 4 2003
T. Wendler
Abstract Direct adsorption of lipids (DALI) is the first LDL-apheresis method compatible with whole blood. Usually, the blood flow rate is adjusted at 60,80 ml/min, which results in session times of about 2 hr. The present study was performed to test the safety and efficacy of low-density lipoprotein cholesterol (LDL-C) and lipoprotein (a) [Lp(a)] removal by DALI at high blood flow rates in order to reduce treatment time. Thirteen chronic DALI patients in seven centers suffering from hypercholesterolemia (LDL-C 162 ± 42 mg/dl at baseline) and coronary artery disease were treated on a weekly or biweekly basis by DALI apheresis. The blood flow rate QB was held constant for at least two sessions, respectively, and was increased from 60 to 80, 120, 160, 200, and 240 ml/min. All patients had pre-existing av-fistulas. The anticoagulation was performed by a heparin bolus plus ACD-A at a ratio of citrate: blood ranging from 1:20 to 1:90. Clinically, the sessions were well tolerated and only 26/201 sessions (12%) of the treatments were fraught with minor adverse events. Acute LDL-C reductions (derived from LDL-C levels determined by lipoprotein electrophoresis) averaged 72/66/60/53/50/48% for QB = 60/80/120/160/200/240 ml/min. Lp(a) reductions were 68/67/62/60/58/56%, whereas HDL-C losses were ,10%. Routine blood chemistries and blood cell counts remained in the normal range. Treatment times averaged 142/83/45 min at Qb = 60/120/240 ml/min. On average, DALI LDL-apheresis could be performed safely and effectively at high blood flow rates up to at least 120 ml/min in patients with good blood access, which significantly reduced treatment time from 142 to 83 min (,42%). J. Clin. Apheresis 18:157,166, 2003. © 2003 Wiley-Liss, Inc. [source]

Direct adsorption of low-density lipoprotein and lipoprotein(a) from whole blood: Results of the first clinical long-term multicenter study using DALI apheresis,

JOURNAL OF CLINICAL APHERESIS, Issue 4 2002
T. Bosch
Abstract Direct adsorption of lipoproteins (DALI) is the first low-density lipoprotein (LDL)-apheresis technique by which atherogenic LDL and lipoprotein(a) (Lp(a)) can be selectively removed from whole blood without plasma separation. The present study was performed to evaluate the efficacy, selectivity and safety of long-term DALI apheresis. Sixty-three hypercholesterolemic coronary patients were treated by weekly DALI sessions. Initial LDL-cholesterol (C) plasma levels averaged 238 ± 87 mg/dl (range 130,681 mg/dl). On average, 34 sessions (1,45) were performed processing 1.5 patient blood volumes. The primary aim was to acutely reduce LDL-C by ,60% per session. To this end, three different adsorber sizes could be employed, i.e., DALI 500, 750, and 1,000, which were used in 4, 73, and 23% of the 2,156 sessions, respectively. On average, 7,387 ml of blood were processed in 116 min per session. This resulted in the following mean acute changes: LDL-C 198 , 63 mg/dl (,69%), Lp(a) 86 , 32 mg/dl (,64%), triglycerides 185 , 136 mg/dl (,27%). HDL-C (,11%) and fibrinogen (,15%) were not significantly influenced. The mean long-term reduction of LDL-C was 42% compared to baseline while HDL-C slightly increased in the long run (+4%). The selectivity of LDL removal was good as recoveries of albumin, immunoglobulins, and other proteins exceeded 85%. Ninety-five percent of 2,156 sessions were completely uneventful. The most frequent adverse effects were hypotension (1.2% of sessions) and paresthesia (1.1%), which were probably due to citrate anticoagulation. Access problems had to be overcome in 1.5%, adsorber and hardware problems in 0.5% of the sessions. In this multicenter long-term study, DALI apheresis proved to be an efficient, safe, and easy procedure for extracorporeal LDL and Lp(a) elimination. J. Clin. Apheresis 17:161,169, 2002. © 2002 Wiley-Liss, Inc. [source]

DALI Apheresis in Hyperlipidemic Patients: Biocompatibility, Efficacy, and Selectivity of Direct Adsorption of Lipoproteins from Whole Blood

Simple Purification of Immunoglobulins from Whey Proteins Concentrate

BIOTECHNOLOGY PROGRESS, Issue 2 2006
Benevides C. C. Pessela
We have developed a new protocol with only two steps for purification of immunoglobulins (Ig) from a protein concentrate of whey. Following this protocol, we have an 80% recovery of immunoglobulins, fairly pure. The purification was achieved by eliminating the BSA, via a strong adsorption on DEAE-agarose. Full desoprtion of the other serum proteins could be achieved without contamination with BSA. Thus, a protein solution containing only Ig and very small proteins (e.g., ,-lactoglobulins and ,-lactalbumin) was obtained. Offering this protein mixture to a lowly activated aminated support, only Ig adsorbed on the support. It has been shown that BSA is able to interact with other proteins (including Ig and lactalbumins). This ability to form complexes with other proteins prevented the success of the direct adsorption of Ig on this mildly activated support, even although Ig should be the largest protein presented in dairy whey. [source]