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Biomedical subjects

J K Walter

Publications and source records attributed to J K Walter.

4 recordsLinked to original sources
PubMed1997

Strategies to avoid virus transmissions by biopharmaceutic products.

The use of biopharmaceutical products offers an opportunity for the treatment of many diseases. Biotechnical manufacturing using recombinant mammalian cell lines is the most appropriate method today for the production of biopharmaceutical protein drugs for the treatment of human and animal diseases. However, mammalian cell line derived products have a potential risk for virus transmission to patients who are treated with these biopharmaceutical products. The reliability that biological products are free of any viruses requires a combination of several strategies: The use of well-characterized cell bank systems and, if feasible, the avoidance of biological raw materials for the cultivation of these mammalian cell lines and the production of biopharmaceuticals. Further on, the purification process for biopharmaceuticals has to be validated for its ability to efficiently remove and inactivate any potential virus contamination and, where applicable, also unconventional transmissible agents, such as BSE. In addition, the biopharmaceutical product itself can be tested for the presence of viruses. Like other manufacturing processes, biotechnical production processes have to be performed in compliance with current Good Manufacturing Practices (cGMP).

Animals↗
PubMed1996

Process scale considerations in evaluation studies and scale-up.

This paper focuses on the scale of validation studies that are performed in order to demonstrate viral clearance in downstream processing of biopharmaceutical products. A serious concern for rDNA-derived proteins from recombinant mammalian cell cultures and monoclonal antibodies (MAbs) derived from hybridoma cultures is the potential risk from contaminating retroviral particles or adventitious viruses. Accordingly the downstream process has to be designed to reduce a potential virus load significantly: by virus removal and by virus inactivation methods. Such viral clearance is essential for drug safety- and has to be validated. This means that the design of downstream processing has to take into consideration both the capability for viral clearance and the capability for validation respectively.

Animals↗
PubMed1993

Separation and quantitation of monoclonal antibody aggregates by asymmetrical flow field-flow fractionation and comparison to gel permeation chromatography.

During the downstream processing of monoclonal antibodies (Mab) the formation of dimers and/or oligomers may occur. Today, the most common technique for determination of aggregate content is gel permeation chromatography (GPC) but it has limited resolution and separation speed. Oligomers are particularly difficult to resolve. Asymmetrical flow field-flow fractionation (FFF) is a new analytical method for the separation of Mab aggregates. The monomer and dimer peaks were well resolved and three additional peaks, thought to be trimers, tetramers, and pentamers were partially resolved. The total time for a separation can be kept as short as 6 min. The GPC separation takes about 15 min with less resolution. A study of the reproducibility for the two techniques revealed that the precision was slightly better for GPC. Investigation of the dependence of sample concentration showed that the load limit for FFF was about 4 micrograms of Mab. The GPC technique requires prefiltered samples in order to avoid clogging of the column. For FFF it is possible to inject samples containing precipitated material without any pretreatment. The flow conditions can be adjusted so that the precipitated material elutes with the front, well separated from the monomer peak.

Antibodies, Monoclonal↗