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Biomedical subjects

D G Ross

Publications and source records attributed to D G Ross.

At least 55 records · Page 3Linked to original sources
PubMed1980

Dissemination of an antibiotic resistance plasmid in hospital patient flora.

The 2'' aminoglycoside nucleotidyltransferase, AAD (2''), which adenylates gentamicin, tobramycin, and kanamycin, became prevalent over several months in multiple strains and species of Enterobacteriaceae isolated at one hospital. Eight plasmids with the gene for this enzyme purified from different strains and species isolated at different times had similar EcoRI digestion fragments, indicating that the gene had disseminated on one plasmid without transposition. This 56.5-megadalton plasmid of incompatibility group M, which also carried three other resistance genes, spread, at first, largely in one strain of Klebsiella pneumoniae, which later disappeared. It transferred to some strains which tended not to colonize other patients and later circulated predominantly in Serratia marcescens. Computer surveillance of routine hospital laboratory results was able to detect and trace the gene and the plasmid and measure their effect on resistance prevalence.

Aminoglycosides↗
PubMed1979

Physical structures of Tn10-promoted deletions and inversions: role of 1400 bp inverted repetitions.

We report here the physical structures of deletions and inversions promoted by the translocatable tetracycline-resistance element Tn10. DNA/DNA heteroduplex and restriction enzyme analyses of alterations in the genome of bacteriophage lambda suggest that both types of DNA alterations almost always originate at the internal termini of the 1400 bp terminal inverted repetitions of Tn10. Tn10-promoted deletions remove a single contiguous DNA segment beginning at one such terminus; Tn10-promoted inversions are more complex, and involve both an inversion and a specific deletion of Tn10 DNA.

Chromosome Deletion↗
PubMed1979

Nearly precise excision: a new type of DNA alteration associated with the translocatable element Tn10.

We describe an unusual DNA alteration, "nearly precise excision," which has been identified among tetracycline-sensitive deletion derivatives of lambda phages carrying the translocatable tetracycline-resistance element Tn10. DNA sequence analysis of two such derivatives demonstrates that each retains exactly 50 bp of Tn10 material. The original junctions between lambda and Tn10 sequences remain intact; however, an internal deletion has occurred within Tn10 which eliminates all but the last few base pairs at each end of the element. This deletion occurs within a short A + T-rich inverted repeat which is present near each end of Tn10. Nearly precise excisions occur at frequencies comparable to Tn10-promoted deletions, inversions and translocations, and, like these other events, are independent of phage and bacterial functions for homologous recombination (recA, recB, red). It is not yet clear, however, whether nearly precise excisions are specifically promoted by Tn10 or whether they arise during the course of normal DNA replication processes as a consequence of unusual symmetries present in the DNA sequence at the ends of Tn10.

Base Sequence↗
PubMed1979

A paediatric ventilator with a fluidic control system.

A paediatric ventilator has been designed basically as a fluidic-logic controlled T-piece occluder. Inspiratory and expiratory time, inflation pressure limit, positive end-expiratory pressure (PEEP), continuous positive airway pressure (CPAP) and inspiratory flow-rate are controlled independently and intermittent mandatory ventilation (IMV) is available. Warning systems are provided for failure of the driving as, low airway pressure and inspiratory pressure limit. The breathing circuit is isolated from the control and warning systems for ease of sterilization.

Air Pressure↗
PubMed1979

Translocation and other recombination events involving the tetracycline-resistance element Tn10.

Insertions of Tn10 are characterized by the presence of a direct repetition of a 9-bp target gene sequence on either side the insertion. The occurrence of these repetitions undoubtedly reflects an important feature of the way in which DNA molecules are broken and joined during translocation. Our experiments further suggest, however, that these 9-bp sequences are probably not responsible for Tn10-insertion specificity and that their presence is not required for normal Tn10 translocation elsewhere. We therefore suggest that the genetic information which controls the quality and quantity of Tn10 translocation actually resides somewhere other than these 9-bp sequences. We presume that much of this information lies within the ends of Tn10 itself and that signals on the target DNA which guide Tn10 to preferred positions must occur near, but not actually at, the eventual physical site of the integration event. Consideration of Tn10-promoted deletions and inversions reemphasizes the role of these ends in Tn10-promoted recombination events. Since Tn10-promoted events almost always consist in joining the physical end of one of the putative IS sequences of Tn10 to some other DNA segment, one comes again to the conclusion that these ends must contain important genetic information governing recombination events.

Bacteriophage lambda↗
PubMed1979

The ends of Tn10 are not IS3.

By heteroduplex and hybridization analysis we showed that the inverted repetition (here called IS10) at the ends of the translocatable tetracycline resistance element Tn10 is not IS3, as had previously been reported by Ptashne and Cohen (J. Bacteriol. 122:776--781, 1975). Further analysis confirmed the homology between IS3 and the alpha beta sequence of F and demonstrated that IS10 was not present in the genomes of Salmonella typhimurium LT2 or Escherichia coli K-12.

Base Sequence↗
PubMed1979

Discharge planning.

Explore the source record for details and available documents.

Architectural Accessibility↗
PubMed1978

Properties of the translocatable tetracycline-resistance element Tn10 in Escherichia coli and bacteriophage lambda.

A number of independent insertions into bacteriophage lambda of the translocatable tetracycline-resistance element Tn10 have been isolated and characterized. The physical positions and relative orientations of several such insertions were determined. Two independent insertions appear to lie in the same orientation at or very near the same site in the cI gene, and two more lie in opposite orientations at or near the same position in or near the rex gene. Insertions in or near genes cI, rex, and cIII have been characterized genetically for their effects on expression of nearby genes. Tn10 appears to exert a polar effect on expression of distal genes when it is inserted within an operon, even when expression of that operon is under the influence of lambda N-function. In addition, Tn10 insertions in rex appear to influence in some way expression of an "upstream" gene, cI. Lambda derivatives carrying Tn10 give rise to spontaneously occurring, tetracycline-sensitive deletions at high frequencies. It is likely that formation of these deletions is promoted in some way by the Tn10 element. Lambda::Tn10 phages carrying a Tn10 element that has undergone several successive cycles of translocation since its first isolation and characterization have been analyzed. The results confirm that Tn10 often retains its physical and functional integrity during many cycles of translocation. Lambda derivatives carrying Tn10 have been used to generate insertions of Tn10 in the chromosome of Escherichia coli. This process is independent of recA function, and seems to be quite analogous to the translocation of Tn10 in Salmonella typhimurium as studied previously.

Coliphages↗
PubMed1976

A fluidically controlled ventilator for bronchoscopy.

A simple time-cycled device uses an oscillating, fluidic, bistable element to control the high-pressure oxygen, supply to the ejector of a ventilating bronchoscope. Both manual and automatic modes of function are available, and inflation pressure and respiratory rate are controlled. Its construction is simple, the cost is low and the number of components is small.

Bronchoscopes↗
PubMed1976

Modification of the Hill technique for repair of hiatal hernia.

The major modification of this technique allows accurate placement of sutures through the median arcuate ligament and eliminates the dissection required to expose the aorta at the origin of the celiac artery. Use of a separate row of sutures to create a sling at the esophagogastric junction maintains the desired intraluminal diameter when the esophagogastric junction is secured to the median arcuate ligament.

Hernia, Diaphragmatic↗