PubMed Health⌕ Search

Biomedical subjects

P R Ball

Publications and source records attributed to P R Ball.

7 recordsLinked to original sources
PubMed2002

Robust and sensitive nylon hybridization membrane suitable for high-throughput robotic arraying applications.

An important aspect of automated macroarraying is the suitability of the nylon membrane selected on which samples are to be arrayed. PerForma is a positively charged nylon membrane that has been developed specificallyfor automated macroarraying. Tests usingfluorescent hybridization detection methods have shown that immobilized DNA amounts as low as 0.25 pg can be detected and that positive signals are obtainable after 21 stripping cycles. This report describes the improved colony growth, improved handling characteristics, increased hybridization detection sensitivity, and increased stripping and reprobing capability obtained using PerForma.

Cells, Cultured↗
PubMed2000

Rapid methods for testing the efficacy of sterilization-grade filter membranes.

The validation of sterilization-grade membranes is integral to ensuring the efficient and safe use of microfiltration systems. Here validation refers to the production of sterile filtrate for sterilizing-grade membranes under challenge test conditions. Current validation methods require 48 h of culture for results to become available, which creates time delays within the manufacturing process and quality control (QC) backlogs. This work compares four methods for the production of filter challenge test data, to the desired test sensitivity, within 24 h using bioluminescent and fluorescent recombinant strains of the test organism Brevundimonas diminuta. These methods should provide a way to implement more rapid QC test regimens for filters.

Alphaproteobacteria↗
PubMed1987

Particulate contaminants of intravenous medications and infusions.

Particulate contamination in small volume parenteral medications has been studied and compared with that found in a selection of large volume infusions. Particle counts in 39 commonly used small volume medications and 7 large volume infusions were performed by an automated light blockage method (HIAC) or by optical microscopy. Based on these results and a random survey of drug therapy of intensive care patients, it is concluded that the contribution of intravenous medications to the total particle load received by such patients is likely to be many times greater than from infusion fluids. Until firm evidence regarding the harmful systemic effects of drug particles is available and the manufacturing regulations adjusted appropriately, final in-line filtration of infusions immediately proximal to the intravenous cannula should be considered when drugs are being given intravenously.

Drug Contamination↗
PubMed1980

Evidence for more than one mechanism of plasmid-determined tetracycline resistance in Escherichia coli.

The basis of tetracycline resistance mediated by TetA determinants and joint resistance to tetracycline and minocycline coded by TetB determinants was investigated. The TetA class of determinants was represented by those carried on plasmids pSC101, RP1 and pIP7 and TetB by Tn10. The relationships between expression of tetracycline and minocycline resistance and accumulation of these antibiotics suggest that there are three mechanisms of plasmid-determined resistance conferring (1) about a 10- to 20-fold increase in resistance to tetracycline that is not associated with decreased antibiotic accumulation, (2) a 4- to 7-fold increase in resistance to tetracycline that is associated with decreased drug accumulation, and (3) about a 2- to 3-fold increase in resistance to both tetracycline and minocycline that is not associated with decreased accumulation of either antibiotic. Mechanism 1 was coded by the tetracycline resistance determinant of pSC101 (TetA), mechanisms 1 and 2 by the determinants in RP1 and pIP7 (TetA) and all three mechanisms by Tn10 (TetB).

Drug Resistance, Microbial↗
PubMed1977

Lysozyme-promoted association of protein I molecules in the outer membrane of Escherichia coli.

Incubation of whole envelopes prepared from sonically oscillated Escherichia coli K-12 cultures with lysozyme in vitro resulted in the appearance of a protein species with an apparent molecular weight double that of outer membrane protein I. Similar dimers were also detected in purified outer membranes and whole envelopes from lysozyme-induced spheroplasts of E. coli K-12. This was confirmed by two-dimensional electrophoresis in which the dimers were resolved in the second dimension to run as single polypeptides of protein I. Formation of dimers was correlated with peptidoglycan degradation, but the ability of protein I molecules to associate may vary between strains of E. coli, since dimers were found only in outer membranes from E. coli W7. We suggest that extensive degradation of peptidoglycan leads to nonspecific formation of protein I aggregates, but that these aggregates do not occur in vivo.

Bacterial Proteins↗