DNA in bacterial chromosomes and bacterial plasmids is supercoiled. DNA supercoiling is essential for DNA replication and gene regulation. However, the density of supercoiling in vivo is circa twice smaller than in deproteinized DNA molecules isolated from bacteria. What are then the specific advantages of reduced supercoiling density that is maintained in vivo? Using Brownian dynamics simulati...

A simple and rapid mixed-phase method for the quantitative assay of 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase and a procedure for the efficient reactivation of Mg-ATP-inactivated microsomal HMG-CoA reductase by potato acid phosphatase are described. The mixed-phase assay entails the direct addition of the acidified, deproteinized incubation mixture to a toluene-based scintillation fluor. T...

An assay for determining the concentration of pyridoxal Y-phosphate in plasma from 0.4 ml whole blood is reported. The assay consists of incubating deproteinized plasma with o-setine apodehydratase from Escherichia cob’ in 0.5 M N-2-hydroxyethylpipetazine-N’-3-propesulfonic acid, pH 7.8, at 37°C for 15 mitt, and then determining the o-serine dehydratase activity of an aliquot of the incubation ...

Extracellular vesicles (EVs) have been proposed as a means to promote intercellular communication. We show that when human primary cells are exposed to cancer cell EVs, rapid cell death of the primary cells is observed, while cancer cells treated with primary or cancer cell EVs do not display this response. The active agents that trigger cell death are 29- to 31-nucleotide (nt) or 22- to 23-nt ...

Soluble antigens from Histoplasma capsulatum in the mycelial and yeast phase were purified by gel filtration, fixed onto paper discs, and employed in an indirect immunofluorescence procedure to detect antibody in sera from individuals infected with H. capsulatum. The elution patterns of crude histoplasmin passed through Sephadex G-200 revealed two minor peaks of protein showing immunofluorescen...

We describe a "high-performance" liquid-chromatographic assay for quantifying cefamandole in biological fluids from patients with renal impairment. Serum samples are deproteinized with acetonitrile, then extracted with dichloromethane; dialysis-fluid samples are injected directly; urine samples are diluted appropriately before injection onto the reversed-phase column. The mobile phase is a meth...

A liquid chromatographic-mass spectrometric method for the determination of cortisol in serum using atmospheric pressure electrospray ionization and tandem mass spectrometry is described. During sample preparation, 150 microl of serum were deproteinized with methanol/zinc sulfate followed by on-line solid phase extraction employing column switching. Tri-deuterated cortisol was used as the inter...

A simplified procedure is described for the determination of inorganic phosphate in body fluids. The method employs two stable reagents and requires a minimum number of steps. Serum is deproteinized with trichioroacetic acid containing ferrous ion and thiourea. The supernatant is decanted and mixed with a small volume of molybdic acid. The phosphomolybdate formed is immediately reduced in situ ...