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Biomedical subjects

G E Wilson

Publications and source records attributed to G E Wilson.

44 records · Page 3Linked to original sources
PubMed1979

Improved blood culture technique based on centrifugation: clinical evaluation.

A total of 3,335 blood samples from 1,180 patients suspected of having bacteremia were analyzed concurrently by two methods: (i) supplemented peptone broth with sodium polyanethanol sulfonate and a CO2 atmosphere; and (ii) lysis centrifugation at 3,000 X g for 30 min onto a high-density, hydrophobic cushion. The centrifugation technique recovered 80% of the positive cultures as compared with 67% for the broth method. The centrifugation technique showed an apparent increase in the isolation of staphylococcus aureus, Pseudomonas, and yeasts. In almost every instance, the time required for detection of a positive culture was shortest for the centrifugation method. Contamination rates for both systems were comparable (1.4%). Quantitation, offered only by the centrifugation method, proved useful on several occasions in discriminating between an opportunistic infection versus a skin contaminant and in judging efficacy of antimicrobial therapy.

Bacteria↗
PubMed1977

Magnetic resonance studies of the manganese guanosine di- and triphosphate complexes with elongation factor Tu.

Analysis of titration data of EF-Tu-GDP with Mn(II) where free and bound Mn(II) were determined by proton relaxation rate of water (PRR) yields one tight Mn(II) binding site and a value of 2 muM for the dissociation constant of Mn(II) from the EF-Tu-MnGDP complex, K'A. The dissociation constant of manganese nucleotide from the ternary EF-Tu-MnGDP complex, K2, 0.2 muM, was derived from the known value of Ks, the dissociation constant for the binary EF-Tu-GDP complex, and the titration data of the ternary complex with excess GDP as titrant. The apparent number, n, of rapidly exchanging water ligands coordinated to bound Mn(II) in the ternary complex EF-Tu-MnGDP is estimated from the frequency dependence of the PRR of the complex to be approximately 1. The value of n and the values of PRR enhancements, epsilont = 4.3 for EF-Tu-MnGDP at 21 degrees, 24.3 MHZ and epsilont = 4.1 for the ternary GTP complex, are unusually low for protein-Mn-nucleotide complexes. The antibiotic X5108 which induces GTPase activity in EF-Tu-MgGTP was shown to bind stoichiometrically to EF-Tu-MnGDP and thereby change the PRR enhancement of the complex from 4.3 to 7.4. The characteristic broad lines in the EPR spectra of Mn(II) nucleotides are strikingly narrowed upon binding of Mn(II) nucleotides to EF-Tu. The long electron spin relaxation times inferred from the EPR spectra indicate a limited access of solvent water to the first coordination sphere of Mn(II) in its EF-Tu-nucleotide complexes. The frequency dependence of the PRR indicates that the electron spin relaxation time, T1e, is the dominant process modulating the Mn(II)-H2O interaction of the EF-Tu-MnGDP complex and consequently determines the correlation time. The value of T1e, estimated from the PRR experiments to be 2.5 ns at 21 degrees, is consistent with the lower limit of T1e obtained from the line widths of the EPR spectrum of the complex. Upon binding of a stoichiometric quantity of the antibiotic X5108, the EPR spectrum of EF-Tu-MnGDP is severely broadened indicating greater access of solvent water to the manganese coordination sphere, i.e. an opening of the nucleotide binding site as already suggested by the increased PRR enhancement.

Binding Sites↗