Cobas Integra: clinical laboratory instrument with continuous and random-access capabilities.

The Cobas Integra from Roche Diagnostic Systems is a new clinical laboratory analyzer with continuous and random-access features for routine chemistries, specific proteins, electrolytes, hormones, therapeutic drugs, and drugs of abuse. The system maintains 68 test-specific reagent cassettes on board, along with multiple ion-selective electrodes (ISEs) for electrolyte determinations. This gives the Cobas Integra the capability of analyzing as many as 72 analytes without having to load additional reagents. We describe the basic analyzer configuration and the subsystems for absorbance, fluorescence polarization, and ISE measurements. Performance characteristics for precision, methods comparison, and on-board stability are given for assays representative of the various test groups. The 29 Cobas Integra tests evaluated in the present study show good agreement (r > or = 0.98 and slopes generally 0.90 to 1.12) with the respective methods available on either the Olympus AU5000, Hitachi 911 or 717, Behring BNA, or Abbott TDx systems. Total assay precision (CV) ranged from 0.8% to 8.5%, and calibration curves were stable for as long as 20 weeks. Test throughput, which is dependent on pipetting sequence, was determined to be up to 600 tests per hour without ISE and up to 750 tests per hour with ISE; the time to first result was 2.0-10.0 min.

Biosynthesis of streptomycin. dTDP-dihydrostreptose synthase from Streptomyces griseus and dTDP-4-keto-L-rhamnose 3,5-epimerase from S. griseus and Escherichia coli Y10.

dTDP-dihydrostreptose synthase from Streptomyces griseus was purfied about 50-fold by removal of protein with polyethyleneimine, (NH4)2SO4 fractionation and gel filtration on Ultrogel AcA44. The synthase preparation was free of dTDP-4-keto-L-rhamnose 3,5-epimerase (dTDP-4-keto-6-deoxy-D-glucose 3,5-epimerase, EC 5.1.3.13) activity. A new enzyme assay using Escherichia coli Y10 as source for the epimerase and dTDP-glucose 4,6-dehydratase (dTDP-glucose 4,6-hydro-lyase, EC 4.2.1.46) was developed. In the presence of excess epimerase the apparent Km for dTDP-4-keto-6-deoxy-D-glucose was determined to be 25 microM. The molecular weight of epimerase and synthase were determined by their elution volumes from a Sephadex G-100 column to be approx. 67,000 and 32,000, respectively. The pH optimum for the epimerase was between 7.5 and 8.5. The intermediate formation of dTDP-4-keto-L-rhamnose in the epimerase reaction could be shown by detection of 6-deoxy-[3H]talose after NaB3H4 reduction. Results which indicate the existence of dTDP-4-keto-6-rhamnose as a free intermediate in the epimerase reaction are reported.