FOR IMMEDIATE RELEASE

May 29, 2003

Guava Technologies Inc announces a proprietary method that improves the productivity and substantially reduces the labour costs associated with automated cell counting and viability determination.

A new standard for cell counting and viability assessment

Guava Technologies Inc, a leading provider of bench-top cellular analysis systems, has announced a proprietary method that improves the productivity and substantially reduces the labour costs associated with automated cell counting and viability determination.

The Guava ViaCount™ assay provides rapid cell counts and viability determination based on the differential uptake of fluorescent reagents. Using the compact Guava Personal Cell Analysis (PCA) system, with ViaCount™ reagent, you can automatically obtain absolute cell counts and viability results. The Guava ViaCount method is typically 10x faster than manual counting with a microscope and hemacytometer allowing you to better maintain optimal tissue culture / bioreactor conditions. Unlike conventional cytometer systems the Guava ViaCount method doesn't require beads for absolute counts and thus is inherently more precise and accurate than other instruments.

Using the Guava ViaCount assay is also very simple and intuitive. To automatically set the threshold of background fluorescence for the cells to be counted, a sample is taken and mixed with PBS that acts as an unstained control. The Guava PCA system then acquires the cell sample mixed with ViaCount reagent. Entering a file name, dilution factor and the volume of each cell culture sample, the ViaCount software program then automatically calculates and exports all results into a spreadsheet that may be simply incorporated into a report.

Further information on the benefits of using the Guava PCA system, with ViaCount™ reagent are available at www.guavatechnologies.com

Guava, PCA and ViaCount are registered trademarks of Guava Technologies, Inc. All other registered trademarks and trademarks are owned by their respective companies.

CONTACTS:

Guava Technologies 25801, Industrial Boulevard Hayward, CA 94545-2991 USA www.guavatechnologies.com EUROPE: Dr Bill Bradbury tel.: 44-208-546-0869 email: wbprimetek@aol.com N.AMERICA Marie Martin tel.: +1-510-576-1427 email: mmartin@guavatechnologies.com Joan Kureczka tel.: +1-415-821-2413 email: jkureczka@aol.com