Appeal No. 2001-0380 Page 4
Application No. 08/676,971
examiner (Answer, page 4) Griffiths (page 55, Figure 8, examples D-F), discuss
the “[t]ypes of impellers for growing suspension and microcarrier cells.” As the
examiner explains (Answer, page 4), “magnetic drive stirrers provide a more
homogeneous liquid/cell suspension via axial and radial flow as well as laminar
and turbulent mixing.” However, Griffiths teaches (page 62), “[t]he energy
generated at the tip of the stirrer blade is a limiting factor as it gives rise to a
damaging shear force. Shear forces are created by fluctuating liquid velocities in
turbulent areas.” According to Griffiths (page 63), “[t]he greater the turbulence
the more efficient the mixing, but a compromise has to be reached so that cells
are not damaged.” As Griffiths point out (id.), “[i]f the cells are too fragile for
stirring, or if sufficient mixing cannot be obtained without causing unacceptable
shear rates then an alternative mixing system may have to be used.”
In response, the examiner maintains (Answer, page 14):
one of ordinary skill in the art would have had a high
expectation of successfully maintaining high growth levels
and minimizing cell damage, i.e., foaming, of the fragile
ciliates by modifying the culture method of Hofmann et al. to
gently mix the cells and medium with overhead magnetic
stirring, and to renew nutrients by batch-fed or cyclic
medium exchange methods.
The examiner, however, identifies no evidence to support this conclusion. In this
regard, we remind the examiner that “[t]he consistent criterion for determination
of obviousness is whether the prior art would have suggested to one of ordinary
skill in the art that this process should be carried out and would have a
reasonable likelihood of success, viewed in the light of the prior art.” In re Dow
Chemical Co. 837 F.2d 469, 473, 5 USPQ2d 1529, 1531 (Fed. Cir. 1988).
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