Biomedical subjects

K Pock

Publications and source records attributed to K Pock.

5 recordsLinked to original sources

PubMed2006

Characterisation of a novel high-purity, double virus inactivated von Willebrand Factor and Factor VIII concentrate (Wilate).

This study summarises the biochemical and functional properties of a new generation plasma-derived, double virus inactivated von Willebrand Factor/Factor VIII (VWF/FVIII) concentrate, Wilate, targeted for the treatment of both von Willebrand disease (VWD) and haemophilia A. The manufacturing process comprises two chromatographic steps based on different performance principles, ensuring a high purity of the concentrate (mean specific activity in 15 consecutive production batches: 122 IU FVIII:C/mg total protein) and, thus, minimising the administered protein load to the patient (specification: < or = 15 mg total protein per 900 IU Wilate). The optimised solvent/detergent (S/D) treatment and prolonged terminal dry-heat (PermaHeat) treatment of the lyophilised product at a specified residual moisture (RM) provide two mechanistically independent, effective and robust virus inactivation procedures for enveloped viruses and one step for non-enveloped viruses. These process steps are aggressive enough to inactivate viruses efficiently, but yet gentle enough to maintain the structural integrity and function of the VWF and FVIII molecules, as proven by state-of-the-art assays covering the diverse features of importance. The VWF multimeric pattern is close to the one displayed by normal plasma, with a consistent content of more than 10 multimers, but a relatively lower portion of the very high multimers. The multimeric triplet structure is normal, underlining the gentle and effective manufacturing process, which does not require the addition of protein stabilisers at any step. The balanced activity ratio of VWF to FVIII is close to that of plasma from healthy subjects, rendering Wilate suitable also for the safe and effective treatment of patients with VWD.

Blood Proteins↗

PubMed2001

Characterization of clotting factor IX in plasma-derived preparations by electrophoretic techniques.

Clotting factor IX preparations from human plasma (pdFIX) have been characterized using electrophoretic methods like sodium dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing and two-dimensional polyacrylamide gel electrophoresis. Factor IX prior to and after activation with factor XIa was separated by one- and two-dimensional polyacrylamide gel electrophoresis and on isoelectric focusing gels. The main differences between the band patterns of the two pdFIX preparations are due to their purity. Vitronectin was identified by immunological techniques as major accompanying plasma protein, separated from factor IX and characterized by isoelectric focusing and two-dimensional polyacrylamide gel electrophoresis.

Amino Acid Sequence↗

PubMed2001

Vitronectin in clotting factor IX concentrates.

Highly purified, plasma-derived factor IX (FIX) concentrates are produced in large part by a combination of anion exchange and heparin affinity chromatography. However, the concentrates still contain some accompanying proteins. The main impurity has turned out to be the adhesive glycoprotein, vitronectin. It occurs in concentrates exclusively in its multimeric form, in contrast to the situation in plasma. The multimeric vitronectin can be removed either by nanofiltration with a crossflow system or by size-exclusion chromatography. When these FIX concentrates are used as therapeutic agents, the fact has to be taken into account that considerable amounts of multimeric vitronectin are given to the patient. The physiological consequences of the dosage of this protein have not yet been investigated. Although no thrombogenicity has been reported in connection with the above-mentioned FIX concentrates, we recommend that the impurity should be removed from the preparation with the methods described here.

Blood Coagulation Factors↗

PubMed1999

Use of high-resolution techniques for the characterization of clotting factor VIII.

Dealing with the structural characterization of clotting factor VIII (FVIII) requires the application of several high-resolution analytical techniques. Besides the analytical point of view, a detailed knowledge of FVIII structure, production and therapeutic application is necessary. This review gives an overview of most of the currently applied analytical methods and how they deal with the complex analytical problem, investigating FVIII in a sample matrix containing large amounts of accompanying plasma proteins.

Factor VIII↗

PubMed1999

Degradation products of factor VIII which can lead to increased immunogenicity.

The biochemical and immunochemical aspects of the development of inhibitors with a plasma-derived, double-virus inactivated factor VIII (FVIII) concentrate (marketed as Octavi SDPlus in Germany and Bisinact in Belgium) are described. A total of 12 cases of inhibitor formation (predominantly type II) were reported in Germany, 8 in Belgium but none in Portugal. Initially, the only difference between the non-pasteurised, SD virus-inactivated product Octavi and the pasteurised product Octavi SDPlus appeared to be pasteurisation, though subsequently, the quality of source material for the product was found to differ in different countries. Separation studies revealed the presence of a 40 kDa peptide fragment in some batches. It was subsequently shown that there was a strong correlation between inhibitor development and batches containing the 40 kDa marker, and a relationship between elevated markers of coagulation activation (FPA in particular) and the occurrence of the 40 kDa marker. Further work revealed that analytical methods commonly used for quality control were not suitable to highlight batch-to-batch differences. It was concluded that inhibitor potential (neoantigenicity) in Octavi SDPlus arose due to two effects; degradation of FVIII already present in source material; and heating of unstable FVIII degradation products. In this case, inhibitors were not caused by the overall production process, nor by GMP failures. The problem of inhibitor potential can be avoided if appropriate preventive measures are taken. Further work is needed to prove non-neoantigenicity and to reinforce the scientific findings, and to characterise pilot batches.

Chromatography, High Pressure Liquid↗