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B Inglis

Publications and source records attributed to B Inglis.

16 recordsLinked to original sources
PubMed1992

Lethal and mutational effects of solar and UV radiation on Staphylococcus aureus.

Strains of Staphylococcus aureus, an opportunistic pathogen commonly found on human skin, were exposed to sunlight and UV C radiation, and the lethal and mutational effects measured. Sunlight killed cells with an inactivation constant of 3 x 10(-5) per joule per square metre; UV C was much more lethal, giving an inactivation constant of approximately 0.1 per joule per square metre. Some strains tested showed a sensitivity to sunlight that was dependent on the growth phase of the cells, exponentially growing cells showing a greater sensitivity. Mutational effects of irradiation were measured by the appearance of mutants sensitive to methicillin following irradiation of a multiresistant strain. Mutants appeared at a frequency of 10(-3); this high frequency of mutation in the region of the mec gene has also been observed when multiresistant strains are subjected to nutritional or thermal stress. Mutants showed the same chromosomal alteration (seen in pulse-field gel electrophoresis of SmaI-digested DNA) whether induced by solar or UV C irradiation.

DNA Damage↗
PubMed1992

Physical mapping of the mec region of an Australian methicillin-resistant Staphylococcus aureus lineage and a closely related American strain.

Methicillin-resistant (Mcr) staphylococci contain chromosomal DNA that is absent from Mcs cells. This extra DNA harbours the methicillin resistance determinant mec and often other resistance determinants. The mec region can differ substantially in structure among different isolates. We present studies on the mec region of a group of Staphylococcus aureus isolates prevalent in Australia and London. Southern hybridization analyses of a prototype Australian isolate, ANS46, and an isogenic Mcs deletion mutant, ANS62, allowed the physical map of the region to be extended to 55 kb. The DNA corresponding to the deletion, which includes mec and resistance determinants for mercury, cadmium (Cd) and tetracycline, amounted to 41 kb. It was bounded precisely at one end by the macrolides-lincosamides-streptogramin B (MLS)-resistance transposon, Tn554. Near the other end was an element with homology to Tn554, psi Tn554, which carried the Cdr determinant. The mec region of an American Mcr isolate, R35, was found to be virtually the same as that of ANS46, except that it lacked Tn554. Another class of American Mcr isolates, prevalent since 1987, differs markedly from ANS46 in mec region organization. However, this other American class also contains an insertion of Tn554 in the mec region, and the attachment site for this insertion was found to have significant homology to attachment sites for the Tn554 and psi Tn554 insertions in the mec region of the Australian strain. These results suggest possible roles of Tn554 and Tn554-like elements in the evolutionary variation of the mec region.

Australia↗
PubMed1991

The effect of muscle vibration on human position sense during movements controlled by lengthening muscle contraction.

Muscle vibration studies suggest that during voluntary movement limb position is coded by muscle spindle information derived from the lengthening, antagonist muscle. However, these investigations have been limited to movements controlled by shortening contractions. This study further examined this property of kinesthesia during movements controlled by lengthening contraction. Subjects performed a horizontal flexion of the right forearm to a mechanical stop randomly positioned at 30, 50 and 70 degrees from the starting position. The movement was performed against a flexor load (1 kg) requiring contraction of the triceps muscle. Vision was occluded and movements were performed under three conditions: no vibration, vibration of the right biceps and vibration of the right triceps. The perceived position of the right forearm was assessed by instructing subjects to simultaneously match the right limb position with the left limb. Vibration of the shortening biceps muscle had no effect on limb matching accuracy. However, triceps vibration resulted in significant overestimation of the vibrated limb position (10-13 degrees). The variability in movement distance was uninfluenced by muscle vibration. During movements controlled by lengthening contraction, there is a concurrent gamma dynamic fusimotor input that would enhance primary afferent discharge. Despite this additional regulating input to the muscle spindle, it appears that muscle spindle information from the lengthening muscle is important for the accurate perception of limb movement and/or position.

Adult↗
PubMed1991

Epidemiological analysis of a methicillin-resistant Staphylococcus aureus outbreak using restriction fragment length polymorphisms of genomic DNA.

The genomic DNA of 58 isolates of methicillin-resistant Staphylococcus aureus (MRSA) obtained during an infection outbreak at two major Canberra hospitals was analysed for restriction fragment length polymorphism (RFLP) by digestion with the endonuclease SmaI and resolution of the fragments by pulsed-field gel electrophoresis. Based on the fraction of common fragments generated by the endonuclease, DNA similarities among the isolates were estimated. Distance matrix analysis showed that the MRSA isolates could be divided into two major clusters (RFLP types I and II) and one minor one (type 46). A fourth group of miscellaneous isolates was found to be heterogeneous in terms of DNA sequence similarity. The epidemiological data indicated that RFLP type I was most common in the intensive care units in the two hospitals, with particular subtypes of RFLP type I concentrated in individual units. RFLP type II and the miscellaneous group were more generally distributed. Type 46 isolates appear to be related to a group which was present in epidemics in Melbourne hospitals in the early 1980s. Using the standard phage set, the RFLP type I group was largely untypable. However, type II isolates were all phage typable, with a shared susceptibility to phages 29/85/95/90; type 46 isolates had a shared susceptibility to phages 85/90. The miscellaneous isolates were of variable phage types.

Australia↗
PubMed1990

Bacteriophage 604: a marker phage for multi-resistant Staphylococcus aureus in Australia.

Of 28 multi-resistant isolates of Staphylococcus aureus collected during 1986 from hospitals in major cities around Australia, 27 were found to contain the same prophage (denoted phage 604). Hospital isolates carrying three or fewer resistance markers, and community isolates carrying one or no resistance markers, did not carry this prophage. Phage 604 does not confer antibiotic resistance on its lysogens, nor does it increase virulence in chick embryo assays. Phage 604 appears to be a correlate of antibiotic multi-resistance in S. aureus in Australia, and may provide a molecular marker for incipiently epidemic strains of this bacterium in Australian hospitals.

Animals↗
PubMed1990

Induced deletions within a cluster of resistance genes in the mec region of the chromosome of Staphylococcus aureus.

Variants of a methicillin-resistant Staphylococcus aureus showing loss of or reduced resistance to the antibiotic were isolated at frequencies of 0.1-100% from cultures which had been starved, grown at elevated temperature, or given small doses of UV radiation. Three types of variant were identified on the basis of population distribution of resistance to the antibiotic, and field-inversion gel electrophoresis of digests of the chromosome cut with the rare-cutting restriction endonuclease SmaI. Type I variants are methicillin-sensitive and have a deletion in the mec region of the chromosome. Type II variants have reduced methicillin resistance and rearranged DNA elsewhere in the chromosome. Type II variants show reduced methicillin resistance and no detectable change in the chromosome. Type I deletions were mapped using cloned fragments from the mec region. In 13 of the 16 independently isolated deletion mutants, one of the deletion endpoints appears to correlate with the positions of insertion sequences or transposons found in this region of the staphylococcal chromosome.

Chromosome Deletion↗
PubMed1988

The expression in Staphylococcus aureus of cloned DNA encoding methicillin resistance.

A 4 kb fragment of chromosomal DNA was cloned from a clinical strain of methicillin-resistant Staphylococcus aureus. It comprises part of a section of the chromosome that was lost when the strain was cured of resistance to methicillin and to other antimicrobial agents. The fragment mediates an increased level of methicillin resistance when inserted into a shuttle vector and transformed back into the sensitive strain generated when the original DNA was deleted.

Chromosomes, Bacterial↗
PubMed1988

Mercury and tetracycline resistance genes and flanking repeats associated with methicillin resistance on the chromosome of Staphylococcus aureus.

Sections of a cloned 27 kb segment of chromosomal DNA, associated with resistance to four antimicrobial agents in a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA), were tested for their ability to determine resistance when transformed into a sensitive laboratory strain of S. aureus. This was achieved by inserting the sections into a newly constructed shuttle vector, amplifying the recombinant DNA in E. coli, and transforming protoplasts of the sensitive S. aureus strain. Two sections of the cloned DNA were found to determine resistance separately to mercuric ion and to tetracycline, in both S. aureus and Escherichia coli.

Chromosomes, Bacterial↗
PubMed1987

Molecular relatedness of Staphylococcus aureus typing phages measured by DNA hybridization and by high resolution thermal denaturation analysis.

Fifteen bacteriophages representative of the serological and lytic groups of the International Typing Set for Staphylococcus aureus were examined for genomic homology by DNA hybridization and by analysis of high resolution thermal denaturation profiles. Phages 11 and 80 alpha, not part of the set, were also examined. DNA homology measured by filter hybridization showed values ranging from near zero to 88 per cent in pair-wise comparisons. Cluster analysis of these data by standard numerical taxonomical methods yielded clusters which closely reflect the subdivision of the international set on the basis of serological reactions. High resolution thermal denaturation analysis yielded characteristic profiles for each phage DNA, with members closely related by hybridization analysis showing only minor differences. Quantitative analysis of the extent of overlap of these profiles generated relational values which were subjected to the same numerical taxonomic analysis as for the DNA hybridization data. The resultant dendrogram was qualitatively different only in minor respects from that derived from the hybridization analyses, but quantitatively homology was greater by 80 per cent or more for the DNAs which were least related according to the hybridization analyses. This upward shift in measured homology appears to reflect the similar base composition of the DNAs from these phages. Statistical comparison of the homology data obtained by the two methods showed them to be significantly correlated. These results indicate that the International Typing Set consists of phages which all appear to be related to a greater or lesser extent. If, as the history of the collection of these phages indicates, they are a random sample of aureophages, then this group of phages may represent a common genetic pool within which recombination, mutation, and genome rearrangement occur to generate unique individual phages.

DNA, Viral↗
PubMed1979

Galactose-1 phosphate uridyl transferase deficiency in the western grey kangaroo (Macropus fuliginosus; marsupialia): a model system for gene therapy studies.

The western grey kangaroo (Macropus fuliginosus) was found to be deficient for galactose-1 phosphate uridyl transferase (GPUT). This species could be used therefore for studies of gene therapy techniques. An improved GPUT assay procedure was developed. It was found that phage particles injected intravenously remain in the blood of kangaroos until the particles are removed by the reticuloendothelial system or, if this system is overloaded, the particles are inactivated by the immune system four days later. No effective transgenosis was detected of the bacterial gal operon contained in the phage used.

Animals↗
PubMed1975

Fringe medicine.

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Acupuncture Therapy↗