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1.  Novel method for studying plasmid transfer in undisturbed river epilithon. 
Applied and Environmental Microbiology  1988;54(11):2756-2758.
A method for in situ mating experiments is described which involved overnight incorporation of donors containing the mercury resistance plasmid pQM1 and recipients into the epilithon on separate river stones. The stones were then joined to begin the mating. Transfer frequencies obtained were between 2.2 x 10(-1) and 2.5 x 10(-6) per recipient and appeared to depend on the donor-to-recipient ratio (489/1 to 0.0047/1) and not on the river temperature (12 to 19 degrees C). Controls showed that the low density of donors and recipients at the end of the experiment (3.4 x 10(2) to 7.0 x 10(5) cm-2) did not significantly affect the heterotrophic bacterial count (1.43 x 10(6) to 6.39 x 10(6) cm-2) nor the fluorescent-pseudomonad count (2.3 x 10(4) to 9.33 x 10(4) cm-2).
PMCID: PMC204368  PMID: 3145711
2.  Transfer and Occurrence of Large Mercury Resistance Plasmids in River Epilithon 
In situ mating experiments were done in the River Taff, South Wales, United Kingdom, by using a natural mercury resistance plasmid (pQM1) isolated from a mixture of epilithic bacteria in vitro. The river temperature from March to November was found to influence transfer frequencies strongly (6.8 × 10−9 to 1.5 × 10−2 per recipient). A linear relationship existed between log10 transfer frequency and river temperature (6 to 21°C), a 2.6°C change in temperature giving a 10-fold change in transfer frequency. In vitro experiments showed that pQM1 transferred most efficiently between fluorescent pseudomonads and that one epilithic isolate (Pseudomonas fluorescens) was an efficient donor in situ. Experiments with a P. putida recipient showed that intact epilithic bacterial communities could transfer mercury resistance plasmids in situ at frequencies of up to 3.75 × 10−6 per recipient. Nineteen of the large (>250-kilobase) plasmids isolated by transfer into P. putida were studied in detail and grouped into seven types by restriction digests. Mercury resistance and UV resistance were found to be common linked phenotypes in 19 of the 23 plasmids tested.
PMCID: PMC202582  PMID: 16347617
3.  Improved Multiplex PCR Strategy for Rapid Assignment of the Four Major Escherichia coli Phylogenetic Groups 
Journal of Clinical Microbiology  2012;50(9):3108-3110.
Using data from whole-genome projects, an updated multiplex PCR strategy was developed to assign Escherichia coli isolates rapidly to major phylogenetic groups. This assay accommodates sequence variations detected within target sequences, thereby increasing sensitivity and reliability. It was validated using 185 isolates of known sequence types and showed improved congruence with multilocus sequence typing data.
PMCID: PMC3421818  PMID: 22785193
4.  Development and use of real-time PCR to detect and quantify Mycoplasma haemocanis and “Candidatus Mycoplasma haematoparvum” in dogs 
Veterinary Microbiology  2010;140(1-2):167-170.
Two canine haemoplasma species have been recognised to date; Mycoplasma haemocanis (Mhc), which has been associated with anaemia in splenectomised or immunocompromised dogs, and “Candidatus Mycoplasma haematoparvum” (CMhp), recently described in an anaemic splenectomised dog undergoing chemotherapy. The study aim was to develop quantitative real-time PCR assays (qPCRs) incorporating an endogenous internal control to detect Mhc and CMhp and to apply these assays to DNA samples extracted from canine blood collected in Northern Tanzania (n = 100) and from dogs presented to a Trinidadian veterinary hospital (n = 185).
QPCRs specific for Mhc and CMhp were designed using 16S rRNA gene sequence data, and each was duplexed with an assay specific for canine glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The assays detected ≤10 copies of a sequence-specific haemoplasma plasmid per reaction and neither assay showed cross-reactivity with 106 copies of the sequence-specific plasmid from the non-target canine haemoplasma species.
Nineteen of the 100 Tanzanian samples (19%) were positive for Mhc alone and one (1%) was dually infected. One Trinidadian sample was negative for canine GAPDH DNA and was excluded from the study. Of the 184 remaining Trinidadian samples, nine (4.9%) were positive for Mhc alone, five (2.7%) for CMhp alone, and two (1.1%) dually infected.
This is the first report of canine haemoplasma qPCR assays that use an internal control to confirm the presence of amplifiable sample DNA, and their application to prevalence studies. Mhc was the most commonly detected canine haemoplasma species.
PMCID: PMC2805721  PMID: 19646827
“Candidatus Mycoplasma haematoparvum”; Mycoplasma haemocanis; Polymerase chain reaction; Prevalence; Ticks
5.  Breed, age and gender distribution of dogs with chronic hepatitis in the United Kingdom 
Standardised histological criteria are now available for the diagnosis of canine chronic hepatitis (CH). CH is common in dogs, but no studies have reported breed, age and gender distributions in the United Kingdom (UK). The objective of this study was to determine which breeds had an increased risk for developing CH in the UK and to report the age and gender distribution for those breeds. The databases of six veterinary histopathology laboratories were searched for cases with a histological diagnosis of CH according to standardised criteria. The breed, age and gender of dogs was recorded and compared to a control population to calculate the odds ratio and 95% confidence intervals for developing CH.
A total of 551 cases of CH were identified, consisting of 61 breeds. Nineteen breeds were represented by five or more cases. Breeds with an increased risk for developing CH included the American cocker spaniel, Cairn terrier, Dalmatian, Dobermann pinscher, English cocker spaniel, English springer spaniel, Great Dane, Labrador retriever and Samoyed. The median age at diagnosis for all breeds with CH was 8 years (range 7 months to 16 years). Dalmatians, Dobermann pinschers and English springer spaniels with CH were significantly younger than Cairn terriers, English cocker spaniels and Labrador retrievers with CH. Females were over-represented when all cases were examined together. In conclusion, several breeds in the UK have an increased risk of CH, some of which have not been previously reported.
PMCID: PMC3400054  PMID: 22225827
Dog; Liver; Hepatitis; Breed representation
6.  The co-culture of intestinal epithelial and stromal cells in 3D collagen-based environments 
Regenerative medicine  2009;4(3):397-406.
To investigate the co-culture of established intestinal epithelial cell lines and stromal cells in a series of collagen-based environments for production of tissue engineered intestinal epithelium for in vitro investigations.
Materials & methods:
Intestinal epithelial cells were co-cultured with fibroblasts on a range of supporting collagen matrices, including commercially available Promogran and on collagen-based gels.
Epithelial growth was achieved with one combination of vimentin-expressing stromal and cytokeratin-expressing intestinal epithelial cells grown on collagen gels supplemented with Matrigel, and held at an air-liquid interface.
Collagen-based gels can support the co-culture of intestinal epithelial and stromal cells which results in the growth of an epithelium that has some morphological similarity to normal intestinal tissue.
PMCID: PMC2869023  PMID: 19438315
gut; epithelium; Rat-2; CRL-2102
7.  Effect of Biocides on MS2 and K Coliphages 
Several biocides commonly used in disinfection processes as antibacterial and antifungal agents were tested for activity against MS2 and K coliphages. MS2 was resistant to most biocides; only glutaraldehyde (0.5%) and peracetic acid (1%) achieved a 4-log10 titer reduction in 20 min. In contrast, K phage was sensitive to most biocides, being resistant only to phenol (2%) and chlorhexidine (1%).
PMCID: PMC201628  PMID: 16349309
8.  Phylogenetic Analysis of Hemoplasma Species: an International Study 
Journal of Clinical Microbiology  2003;41(8):3877-3880.
Nearly complete 16S rRNA gene sequences for feline and canine hemoplasma isolates from Europe, Australia, Africa, and Asia showed almost 100% identity to those previously reported for United States isolates. Partial sequences of the RNA subunit of the RNase P gene were also determined, and RNase P-based phylogenetic analysis showed that the hemoplasmas are most closely related to the members of the Mycoplasma pneumoniae group.
PMCID: PMC179806  PMID: 12904408
9.  Effect of discothèque environment on epileptic children. 
A free-field study of 22 epileptic children, selected on the basis of past electroencephalographic abnormality, identified a group who exhibited a significant increase in epileptiform discharge rate on electroencephalography in a discothèque environment (p less than 0.05). Laboratory investigations showed that these children were activated by a wide range of stimuli, including intermittent photic stimulation and exercise. The response to exercise was a good predictor of a child's electroencephalographic response in a discothèque. The findings suggest that most epileptic children are not particularly vulnerable in a discothèque environment.
PMCID: PMC1503941  PMID: 6779939
10.  Measurement of Immunoglobulin Concentrations in the Feces of Healthy Dogs 
Selective immunoglobulin A (IgA) deficiency is the most common primary immunodeficiency in humans and may be associated with chronic gastrointestinal disease. This observation has led to the suggestion that the high susceptibility of German shepherd dogs (GSD) to chronic enteropathies is related to a deficiency in mucosal IgA production. Relative deficiencies of IgA has been reported in the serum, saliva, tears, and feces of GSD both with and without alimentary disease; however, the findings of different studies are not consistent. The aim of this study was to confirm whether a relative deficiency of IgA exists in the feces of GSD. Feces were collected from healthy GSD (n = 209), Labrador retrievers (n = 96), beagles (n = 19), and miniature schnauzers (n = 32). Fecal IgA, IgM, and IgG were measured by capture enzyme-linked immunosorbent assays. Fecal IgG concentrations in the four breed groups were not significantly different. IgA concentrations were significantly greater in miniature schnauzers than in GSD (P = 0.0003) and Labradors (P = 0.0004) but not significantly different from those in beagles. IgM concentrations were significantly greater in miniature schnauzers than in GSD (P < 0.0001), Labradors (P < 0.0001), and beagles (P = 0.0098). These findings do not support the hypothesis that GSD have a relative deficiency in fecal IgA. The differences in immunoglobulin concentrations measured from a single defecation, between individuals of the same breed and between breeds, as well as the lack of an internal control molecule, make the determination of a normal reference range for all dogs impossible. Therefore, the usefulness of fecal immunoglobulin quantification for the assessment of intestinal immunoglobulin secretion in dogs is limited.
PMCID: PMC515266  PMID: 15358641
12.  Cytokine mRNA Expression in Lesions in Cats with Chronic Gingivostomatitis 
Semiquantitative reverse transcription-PCR assays were developed to measure feline interleukin-2 (IL-2), IL-4, IL-5, IL-6, IL-10, and IL-12 (p35 & p40); gamma interferon (IFN-γ); and glyceraldehyde-3-phosphate dehydrogenase mRNA concentrations in biopsies of feline oral mucosa. Biopsies were collected from 30 cats with chronic gingivostomatitis (diseased) prior to each cat receiving one of four treatments. In 23 cases replicate biopsies were collected 3 months after treatment commenced. Biopsies were also analyzed from 11 cats without clinical disease (nondiseased). Expression of IL-2, IL-10, IL-12 (p35 and p40), and IFN-γ was detected in most nondiseased biopsies, while IL-6 was detected in a minority, and IL-4 and IL-5 were both undetectable. Compared to nondiseased cats, the diseased population showed a significant increase in the relative mRNA expression of IL-2, IL-4, IL-6, IL-10, IL-12 (p35 and p40), and IFN-γ. In contrast, IL-5 mRNA expression was unchanged and was only detected in one case. No significant relationship was demonstrable between the change in relative expression of specific cytokine mRNA and the change in clinical severity of the local mucosal lesions over the treatment period. The results demonstrate that the normal feline oral mucosa is biased towards a predominantly (Th) type 1 profile of cytokine expression and that during the development of lesions seen in feline chronic gingivostomatitis there is a shift in the cytokine profile from a type 1 to a mixed type 1 and type 2 response.
PMCID: PMC95710  PMID: 10391845
13.  Distribution of bacterial plasmids in clean and polluted sites in a South Wales river. 
We isolated 400 aerobic heterotrophic bacteria from the sediment of unpolluted and polluted sites in a fast-flowing south Wales river. Isolates were subjected to taxonomic tests and screened for the presence of plasmid DNA by alkaline lysis and agarose gel techniques. There were no significant differences between sites in either the total percentage of isolates containing plasmids (unpolluted site, 9.4%; polluted site, 15%) or in the percentage of non-Pseudomonas-like isolates containing plasmids (unpolluted site, 15%; polluted site, 10%). There were significantly more Pseudomonas-like isolates with plasmids at the polluted site than at the unpolluted site (unpolluted site, 7%; polluted site, 18%). This presumably reflected a response of the nutritionally versatile Pseudomonas-like isolates to conditions at that site. The majority (86%) of the plasmids detected had molecular masses between 35 and 312 megadaltons. These plasmids were large enough to carry genes for conjugal transfer, suggesting the possibility of such transfer in this environment.
PMCID: PMC242142  PMID: 7181499
17.  Temporal and geographical distributions of epilithic sodium dodecyl sulfate-degrading bacteria in a polluted South Wales river. 
Epilithic bacteria were isolated nonselectively from riverbed stones and examined by gel zymography for their ability to produce alkylsulfatase (AS) enzymes and thus to metabolize alkyl sulfate surfactants such as sodium dodecyl sulfate. The percentages of AS+ isolates from stone epilithon at five sites from the source to the river mouth were measured on five sampling days spread over 1 year. The results showed that (i) the prevalence of epilithic AS+ strains (as a percentage of all isolates) was much higher at polluted sites than at the source; (ii) when averaged over the whole river, percentages of AS+ strains were significantly higher at the end of summer compared with either the preceding or the following winter; (iii) analysis of site-sampling time interactions indicated that water quality factors (e.g., biochemical oxygen demand and dissolved oxygen concentration) rather than climatic factors determined the distributions of epilithic AS+ isolates; (iv) constitutive strains were the most prevalent (7.2% of all isolates), with smaller numbers of isolates with inducible (4.5%) and repressible (1.7%) enzymes.
PMCID: PMC202490  PMID: 3355140
18.  Natural transformation in river epilithon. 
Natural transformation was demonstrated in unenclosed experiments incubated in river epilithon. Strains of Acinetobacter calcoaceticus were transformed to prototrophy by either free DNA (lysates) or live donor cells. The sources of transforming DNA and recipient culture were immobilized on filters, secured to stones, and incubated midstream in the river. The transfer frequency generally increased with temperature. No transfer was detected in the river Taff below 10 degrees C. The age of the recipient culture affected the transformation frequencies in situ but did not significantly affect the transfer frequency on laboratory media. Transformation of recipient cultures which had been incorporated into the natural epilithic biofilm and transformation of the plasmid pQM17 in situ were also demonstrated. This study provides the first direct evidence of natural transformation in situ of bacteria incorporated into an indigenous community.
PMCID: PMC168086  PMID: 8702292

Results 1-20 (20)