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Electron Microscopy: Current Techniques Used in Product Safety

by Euan W. Milne
Volume 2, Issue 2 (March/April 2003)

Electron microscopy (EM) provides data for viral clearance studies, information on the presence and quantitation of endogenous retroviruses, and the detection and characterization of other potential contaminants. The technique is favored in this field because it is simple, reliable, and can give reliable quantitation for risk assessments. This article describes the main EM techniques currently used for testing cell cultures, culture supernatants, and bulk harvests. It also includes an in-depth description of a thin sectioning technique used to estimate virus titre in culture supernatants and bulk harvests...

Citation:
Milne EW. Electron Microscopy: Current Techniques Used in Product Safety. BioProcess J, 2003; 2(2): 65-68. http://dx.doi.org/10.12665/J22.Milne.

 
Testing the Null Hypothesis for a Specified Difference — The Right Way to Test for Parallelism

by Janice D. Callahan, PhD and Nancy C. Sajjadi
Volume 2, Issue 2 (March/April 2003)

Testing for parallelism is a fundamental requirement for assessing the validity of bioassay data used to calculate relative potency. When a test sample and the reference material are diluted and assayed, the assumption is that their dose response curves have an identical shape. The standard statistical approach to demonstrate that two curves are parallel involves testing the null hypothesis for equality. This article explains why that approach is not appropriate and presents an argument for testing the null hypothesis for a specified difference to statistically ascertain parallelism...

Citation:
Callahan JD, Sajjadi NC. Testing the Null Hypothesis for a Specified Difference — The Right Way to Test for Parallelism. BioProcess J, 2003; 2(2): 71-77. http://dx.doi.org/10.12665/J22.Callahan.

 
Quantitative Analysis of Monoclonal Antibodies for Nonglycosylated Heavy Chains with a Microfluidic Chip

by Joselina G. Gorniak, Jacob Bongers, PhD, Mark Strohsacker, and Leonard T. Olszewski, PhD
Volume 2, Issue 2 (March/April 2003)

Glycosylation, a posttranslational modification that adds sugars to proteins, is required by many proteins to function properly. Glycosylation can modulate the biological activities of monoclonal antibodies (MAbs), including certain effector functions in the Fc region of IgG antibodies. Monoclonal antibodies produced at higher expression levels by mammalian cell culture may contain small amounts of nonglycosylated heavy chain (NGHC). Recent cell culture mini-reactor studies have shed light on the process parameters that most affect the occurrence of NGHC, and have greatly minimized NGHC levels in IgG MAb products...

Citation:
Gorniak JG, Bongers J, Strohsacker M, Olszewski LT. Quantitative Analysis of Monoclonal Antibodies for Nonglycosylated Heavy Chains with a Microfluidic Chip. BioProcess J, 2003; 2(2): 78-82. http://dx.doi.org/10.12665/J22.Gorniak.

 
Transfected Cell Line Enrichment Using the Gel Microdrop (GMD) Secretion Assay

by Yevgenya Akselband, PhD, Jan Trnovsky, PhD, and Patricia McGrath
Volume 2, Issue 2 (March/April 2003)

The Gel Microdrop (GMD) Secretion Assay involves encapsulating cells within a biotinylated agarose matrix, followed by capture and detection of cell-secreted molecules with fluorescent markers. This technology differs from other encapsulation methods in that the small size of the microdrop (<50 μm diameter) creates a defined microenvironment around the cell without impeding the fusion of nutrients, antibodies, or nucleic acid probes into the GMDs, or the diffusion of secreted products out of the GMDs. Large numbers of GMDs can be readily analyzed using flow cytometry, and sub-populations of rare or high-secreting cells, as small as 0.1%, can be detected and recovered in one day. This assay format is a rapid alternative to limited dilution cloning (LDC)...

Citation:
Akselband Y, Trnovsky J, McGrath P. Transfected Cell Line Enrichment Using the Gel Microdrop (GMD) Secretion Assay. BioProcess J, 2003; 2(2): 83-88. http://dx.doi.org/10.12665/J22.Akselband.

 
Reference Materials for Complex Biological Products

by Keith L. Carson
Volume 2, Issue 1 (January/February 2003)

As advanced analytical techniques become more widely used for product testing, and as more biological products become better characterized, the expectations increase that all biological products will become well characterized. Certainly, the trend is for all regulated products to become better characterized, and for a growing set of analytical methods to attain common usage. As more data is presented in regulatory submissions and reviews, similar data is expected, or desired, in most future product submissions. Furthermore, the techniques being used are opening additional avenues of product testing that regulators may want to see, or that the larger companies could establish as commonly accepted practice...

Citation:
Carson KL. Reference Materials for Complex Biological Products. BioProcess J, 2003; 2(1): 17-21.

 
Advances in High Cell Density Culture Technology Using the Sf-9 Insect Cell/Baculovirus Expression System — The Fed-Batch Approach

by Cynthia B. Elias, PhD, Arno Zeiser, and Amine Kamen, PhD
Volume 2, Issue 1 (January/February 2003)

The Sf-9 insect cell/baculovirus expression system is one of the most commonly used protein expression systems. It is the preferred system for generating large amounts of protein in a short period of time, and it has been successfully used to express several hundreds of different proteins. A representative list of the different proteins made in our laboratory over the past decade with the Sf-9 insect cell/BEVS system is given in Table 1. These proteins are often used in drug screening studies and structure function analysis. Proteins intended for therapeutic purposes are not normally produced using this technology, although a few examples do exist. There is also an unexplored potential for the cells to be used for the production of recombinant viral vectors. Recent reports demonstrating the ability of baculoviruses to express proteins in mammalian cells, with mammalian promoters, indicate that BEVS technology might soon have a major role to play in the field of gene delivery...

Citation:
Elias CB, Zeiser A, Kamen A. Advances in High Cell Density Culture Technology Using the Sf-9 Insect Cell/Baculovirus Expression System — The Fed-Batch Approach. BioProcess J, 2003; 2(1): 22-29.

 
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