Appeal No. 1997-2513
Application No. 08/206,917
page 3) that since flow cytometry utilizes constant volumes of materials, the Stewart
method would require “large volumes” or “enormously large quantities of dilutant” to
obtain low concentrations of particles, particularly at or near zero. The examiner
argues (Answer, page 11) that “the mere allegations by appellant [sic] that achieving
a claimed element by a known method would be ‘difficult’ is not sufficient evidence
that such a limitation could not be achieved,… [Furthermore] end point calibrations
are extremely well known in the art in order to prove the soundness of any instrument
to be used in experimentation.” We agree with the examiner. We also note the
following disclosures in Stewart (page 242) “[t]he number of microspheres should
be kept to a small proportion of the total events analyzed” and:
To determine that the counting methodology was linear over a
wide range of microsphere concentrations, stained CHO cells …
were adjusted to 7.5x105 (±10%) cells/ml. Varying amounts (Tl) of
green or red fluorescent spheres from stock solutions were added to
the cell samples. Since the CHO cell concentration was known, CHO
cells were used to determine the concentration of microspheres in the
cell samples using the flow cytometer. The results in Figure 1 show
that for every conbination tested a linear relationship exists between
the volume (Tl) of spheres added and the concentration of spheres
measured in the cell samples [Stewart, page 240].
Obviousness can only be established by combining or modifying the
teachings of the prior art to produce the claimed invention where there is some
teaching, suggestion, or motivation to do so found either in the references
themselves or in the knowledge generally available to one of ordinary skill in the art.
See In re Fine, 837 F.2d 1071, 1075, 5 USPQ2d 1596, 1598 (Fed. Cir. 1988). The
examiner has demonstrated, and appellants agree, that it would have been prima
facie obvious to a person of ordinary skill in the art at the time the invention was
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