The chromate resistance determinant of Pseudomonas aeruginosa plasmid pUM505 was cloned into broad-host-range vector pSUP104. The hybrid plasmid containing an 11.1-kilobase insert conferred chromate resistance and reduced uptake of chromate in P. aeruginosa PAO1. Resistance to chromate was not expressed in Escherichia coli. Contiguous 1.6- and 6.3-kilobase HindIII fragments from this plasmid hy...

The marked affinity of erythrocytes for hexavalent chromate anion was reported in 1950 by Gray and Sterling (1). Since then, erythrocytes labeled with radioactive sodium chromate have been used extensively for the determination of erythrocyte survival in vivo (1-5) and the determination of blood volume (4-6). The anionic hexavalent form of chromium is bound firmly to erythrocytes, is not reutil...

Human exposure to toxic metals and metalloids in the environment seldom occurs from a single pure compound. Most environmental exposure profiles are heterogeneous with co-exposure occurring coincident with multiple toxic metal species. This co-exposure to metals and metalloids in complex mixtures can result in a synergistic, additive or even depletive toxic response. The complexity of interacti...

S INCE THE INITIAL work of Gray and Sterling,”2 the determination of red cell mass with radioactive sodium chromate has undergone several modifications. Read’ developed the technic of adding ascorbic acid in vitro to the blood-sodium chromate mixture to reduce chromate to trivalent chromium and prevent further uptake by red cells. The inhibition of chromium uptake by ascorbic acid supported the...

A novel, simple, accurate, sensitive, reproducible, economical spectroscopic method was developed and validated for the determination of Azithromycin dihydrate and Cefixime trihydrate in combined dosage form. Second order derivative spectroscopy method is adopted to eliminate spectral interference. The method obeys Beer’s Law in concentration ranges of 10-40 ppm for Cefixime trihydrate and 25-1...