Ex Parte KRANTZ et al - Page 13

                Appeal No. 1996-3973                                                                                                         
                Application No. 08/048,657                                                                                                   

                Phillips both describe determining glucose in human sera/blood using a coupled glucose oxidase                               
                - peroxidase enzyme system and an oxygen acceptor, e.g., 3-methyl-2-benzothiazolione                                         
                hydrazone (MBTH) (see page 392-384 in Ngo and col. 6, lines 45-65 in Phillips).  Both Ngo and                                
                Phillips additionally couple MBTH to 3-(dimethylamino)benzoic acid (DMAB).  According to                                     
                Ngo use of the MBTH-DMAB couple increases the sensitivity and versatility of the glucose                                     
                assay and is safer because MBTH-DMAB  are not carcinogenic like other reagents, e.g., o-                                     
                diansidine, widely used as chromogens for peroxidase-catalyzed reactions (abstract; page 394).                               
                According to Phillips, use of the MBTH-DMAB couple allows for correction of hematocrit and                                   
                degree of oxygenation of blood (col. 10, lines 57-59).  Therefore, it would have been obvious to                             
                one of ordinary skill in the art to modify the generic test slide described by Tietz or Eggert to                            
                assay for a clinically significant analyte, i.e., glucose, using a conventional glucose oxidase-                             
                peroxidase-MBTH reagent system as described by Evans, Ngo and Phillips, and to further use an                                
                MBTH-DMAB couple as suggested by Ngo and Phillips to improve the sensitivity, versatility,                                   
                safety and specificity of the assay, wherein the enzyme and chromogen reactions are separated                                
                into an enzyme and a dye-couple layers, respectively, as suggested by Eggert, and because                                    
                Przybylowicz suggests that separation of reaction steps into separate, discrete layers can enhance                           
                the overall assay reaction.                                                                                                  
                        Claims 1, 2 and 14-19 are rejected under 35 U.S.C.  103 as being unpatentable over                                  
                Przybylowicz, Phillips, Eggert and Tietz.  Przybylowicz, Phillips, Eggert and Tietz have been                                
                discussed above.  Przybylowicz also describes conventional processes for preparing multilayered                              
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