New trends in biological evaluation of medical devices.

More extensive material characterisation and increased determination of toxicological risks are now required when evaluating new medical devices. The new requirements together with other changes in the ISO 10993 series described here suggest how companies can adjust their approach.

Preclinical evaluation of medical devices.

Biological evaluation should be performed as part of risk assessment of the device. It can help define the toxicity and compatibility of the device. This article outlines which tests should be performed, with some examples of specific device test regimes.

Freund's complete adjuvant has a negative impact on egg laying frequency in immunised chickens.

The immunisation of chickens with Freund's Complete Adjuvant (FCA) significantly reduces the egg-laying frequency in comparison to the use of Freund's Incomplete Adjuvant and Hunter's TiterMax. Although FCA results in higher titers of immunospecific antibody in the egg yolk this is counter-balanced by the reduction in number of eggs produced by the chicken. There is consequently no reason to use FCA in chickens when the egg yolk is used as the antibody source.

Comparison of immunospecific antibody response in young and old chickens immunized with human IgG.

Three groups of 18-month-old chickens and three groups of 5-month-old chickens were immunized with human immunoglobulin G (IgG) using one of three adjuvants in the first injection (Freund's Complete Adjuvant (FCA), Freunds Incomplete Adjuvant (FIA) and Hunter's TiterMax (HTM)) following the same immunization scheme. The specific antibody response in serum was measured by ELISA. In both older and younger chickens the serum antibody response in the FCA group reached a significantly higher level (P < 0.01) than in the FIA group and in the HTM group on week 5. The FCA group also had a significantly higher (P < 0.01) response on week 10 compared to the HTM group. Other than that, there was no significant difference between the three adjuvant groups in specific serum antibody response in older chickens. In the younger chickens the specific serum antibody response in the FCA group was significantly higher (P < 0.05) than the response in the HTM group. There was no significant difference in the chicken serum antibody response between the FCA and the FIA groups, nor was there a significant difference between the FIA and the HTM groups. Comparing the younger chickens and the older chickens immunized using the same adjuvant, the older chickens had consistently higher titres than the younger chickens, although the difference was not always significant.

Development and comparison of assays for measuring immunospecific antibody response in serum of chickens and rabbits immunized with human immunoglobulin G.

The antibody response development during polyclonal antibody production is a relevant parameter to monitor during the immunization period to be able to optimize the immunization protocol and to determine the optimal antibody harvest time. Although rabbits and other mammals are most often used for polyclonal antibody production, the chicken is a relevant alternative. There are both scientific reasons, economic reasons, and animal welfare reasons to consider when choosing the chicken instead of a mammal for this purpose, because antibodies in generous quantities can be harvested from the egg yolk. This study compared different assays for measuring antibody response in rabbit and chicken serum. An inhibition liquid phase absorption assay (ILPAA), a rocket immunoelectrophoresis (RIE) assay, and a line immunoelectrophoresis (LIE) assay were compared to ELISAs. The ELISA proved to be the most useful assay for routine use, as it was less time-consuming and because the assay could easily be adapted to both serum antibody types. However, electrophoretic assays were the most useful as combined analytical and quantitative tools and must be considered essential when analyzing specificities of polyclonal antibody preparations.

Immunoglobulin G in the developing oocytes of the domestic hen and immunospecific antibody response in serum and corresponding egg yolk.

The concentration of Immunoglobulin G (IgG) in developing oocytes from normal chickens was measured by ELISA. The concentration was similar in oocytes ranging in size from 6 mm to 38 mm, which is in the last stage of development before ovulation. The concentration of immunospecific IgG was similar in corresponding serum and yolk samples in chickens immunised with human IgG, and a significant linear correlation between response of a specific antibody in the serum and corresponding egg yolk was found. The serum antibody level had to reach a certain level before specific antibody appeared in the egg yolk, and the egg yolk to a certain extent reflected the serum concentration of IgG over 6 to 7 days; because this is the time it takes for the developing oocyte to grow from 6 to 35 mm in diameter.