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Biomedical subjects

J E Moore

Publications and source records attributed to J E Moore.

At least 109 records · Page 6Linked to original sources
PubMed2001

Quantum hall plateau transition at order 1/N.

The localization behavior of noninteracting two-dimensional electrons in a random potential and strong magnetic field is of fundamental interest for the physics of the quantum Hall effect. In order to understand the emergence of power-law delocalization near the discrete extended-state energies E(n) = Planck's over 2piomega(c)(n+1 / 2), we study a generalization of the disorder-averaged Liouvillian framework for the lowest Landau level to N flavors of electron densities ( N = 1 for the physical case). We find analytically the large- N limit and 1/N corrections for all disorder strengths: at N = infinity this gives an estimate of the critical conductivity, and at order 1/N an estimate of the localization exponent nu.

Journal Article↗
PubMed2001

Dynamic curvature strongly affects wall shear rates in a coronary artery bifurcation model.

This study was motivated by the need for a better understanding of coronary artery blood flow patterns and their possible role in atherosclerosis formation. Of particular interest in this study was the effects of the dynamic deformation due to myocardial contraction on wall shear rate patterns in the coronary arteries. A better understanding of these effects on wall shear rate in a bifurcation geometry and an evaluation of the importance of these effects was desired. A three-dimensional computer model of a bifurcation lying on the surface of a sphere with time-varying radius of curvature was employed to simulate the motion and deformation of the arteries. The results indicated low mean shear rates along the myocardial wall and very high shear rate variations (over 100% of the static mean shear rate) along the outer wall. The results obtained using a quasi-static analysis were found to underestimate the dynamic wall shear rate variation along the myocardial and outer walls. It was concluded that dynamic geometry effects are important in determining sites of low mean and oscillating wall shear that have been associated with atherogenesis in curved, bifurcating arteries.

Arteries↗
PubMed2001

PCR-IMS detection and molecular typing of Cryptosporidium parvum recovered from a recreational river source and an associated mussel (Mytilus edulis) bed in Northern Ireland.

PCR-IMS was used to detect Cryptosporidium spp. in environmental water samples in Northern Ireland which had previously tested negative by a conventional IFA staining method. Oocysts of C. parvum detected in river water and final treated sewage effluent collected from various sites along the river Lagan were identified as genotype 2 (animal origin) based on polymorphisms observed at the thrombospondin related adhesion protein gene locus. Similarly, genotype 1 (human origin) oocysts of C. parvum were detected in the marine filter feeder mussel, Mytilus edulis, collected from the shores of Belfast Lough. Detection of the human genotype of Cryptosporidium in mussels destined for human consumption identifies the organism's serious potential as a foodborne pathogen. This work highlights the possible value of monitoring filter feeder systems, in conjunction with specific molecular epidemiological tools, as an alternative monitoring system for the parasite within the aquatic environment.

Animals↗
PubMed2001

Comparison of the value of pulsed-field gel electrophoresis, random amplified polymorphic DNA and amplified rDNA restriction analysis for subtyping Taylorella equigenitalis.

Eight strains of Taylorella equigenitalis were identified by a polymerase chain reaction using a primer pair specific to the 16S rDNA of T equigenitalis. These eight strains were chosen because they had previously been shown to represent eight distinct genotypes by pulsed-field gel electrophoresis analysis after separate digestion of the genomic DNA with ApaI or NotI. The eight strains could be classified into six or seven types by random amplified polymorphic DNA analysis using different kinds of primers. Amplified rDNA restriction analysis after separate digestion with five restriction enzymes, including AluI and MboI, of the 1,500 bp fragments of rDNA amplified by polymerase chain reaction did not discriminate the genomic variations among the eight strains of T equigenitalis. Thus, pulsed-field gel electrophoresis was shown to discriminate these eight organisms better than random amplified polymorphic DNA analysis, while amplified rDNA restriction analysis was found to be unsuitable for subtyping T equigenitalis.

Animals↗
PubMed2001

Demonstration of heterogeneous genotypes of Taylorella equigenitalis isolated from horses in six European countries by pulsed-field gel electrophoresis.

Forty-six isolates of Taylorella equigenitalis were analysed by pulsed-field gel electrophoresis (PFGE) after separate digestion of the genomic DNA with ApaI and with NotI. The isolates had been obtained from horses in six European countries and were classified into 18 genotypes. In Belgium, 2 genotypes were detected in 2 isolates, in England 9 among 15, in Finland 2 in 2, in France 2 among 10, in Sweden 3 among 5, and in Switzerland 3 among 12. Two English isolates and 4 French isolates gave identical PFGE profiles to those of Kentucky 188 from the United States. A common genotype was found in 5 isolates from Belgium and England and also in 10 isolates from France and Switzerland. The analysis of genomic DNA from 12 isolates of T equigenitalis obtained from male horses in France, Sweden and Switzerland gave no evidence of a sex-related difference in the genomic DNA. Genomic DNA from 11 streptomycin (STM)-susceptible isolates obtained in Sweden and Switzerland were classified into four genotypes by PFGE. Each of the six genotypes determined among the 17 isolates from these two countries had single phenotypes for resistance or susceptibility to STM.

Animals↗
PubMed2001

A rapid molecular assay for the detection of antibiotic resistance determinants in causal agents of infective endocarditis.

AIMS: To develop and employ a PCR amplification system, directly from clinical specimens, for the rapid molecular detection of common antimicrobial resistance genes for streptococci, staphylococci and enterococci organisms causing infective endocarditis (IE). METHODS AND RESULTS: Eleven antibiotic resistance genes were targeted by PCR along with four identification-related loci. Blood culture and heart valve material from staphylococcal endocarditis patients were directly examined for methicillin resistance. PCR conditions were optimized for the following antibiotic resistance loci: staphylococci (mecA, aacA-aphD), streptococci (PBP 1A, PBP 2B, gyrB, parE) and enterococci (vanA, vanB, vanC-1, vanC-2, aacA-aphD, aphA3). The presence of methicillin resistance was confirmed in one of the eight IE patients examined. CONCLUSION: This study presents a PCR amplification system for the detection of antibiotic resistance genes. Detection of such genes may indicate susceptibility of the causal agents of IE to commonly prescribed antimicrobial agents. SIGNIFICANCE AND IMPACT OF THE STUDY: Rapid detection of antibiotic resistant organisms may reduce the use of inappropriate antibiotic agents or enable the use of the most appropriate combinations of antibiotics, other than those that would normally be prescribed empirically for IE. Such a method may be particularly valuable in cases of culture-negative endocarditis. Detection of antibiotic resistance genes by molecular-based techniques, namely PCR, will allow more directed antibiotic therapy and may also provide opportunities for earlier identification of resistant organisms.

Drug Resistance, Microbial↗
PubMed2001

Occurrence and molecular genotyping of Cryptosporidium spp. in surface waters in Northern Ireland.

AIMS: To investigate the incidence and genotype of Cryptosporidium parvum oocysts in drinking water sources in Northern Ireland for the period 1996-1999, and to compare conventional and molecular methods of detection. METHODS AND RESULTS: Four hundred and seventy-four waters were investigated by conventional methods, namely immuno-fluorescent antibody detection (IFA; 380) and immuno-magnetic separation-IFA (IMS-IFA; 94), of which 14/474 (3%) were positive. Two hundred and fourteen samples (214/474) were also investigated by PCR techniques, targeting both the 18S rRNA and TRAP-C2 genes, of which 11/214 (5.1%) were positive. These 11 samples were classified as genotype II following sequence analysis of the TRAP-C2 amplicon. CONCLUSIONS: This study demonstrated the low incidence of oocysts of C. parvum in water sources in Northern Ireland. SIGNIFICANCE AND IMPACT OF THE STUDY: Such molecular-based techniques offer a number of advantages over conventional detection methodologies, namely greater sensitivity and specificity as well as the ability to provide accurate genotyping data rapidly, which may be valuable in directing operational management in potential outbreak situations.

Animals↗
PubMed2001

recA genotyping of Salmonella enteritidis phage type 4 isolates by restriction fragment length polymorphism analysis.

AIMS: To subtype Salmonella enteritidis phage type 4 isolates by using recA genotyping. METHODS AND RESULTS: Random amplified polymorphic DNA analysis using a primer ERIC2 of 76 isolates of Salmonella enteritidis phage type 4 obtained in Northern Ireland in 1998 and in 1999 demonstrated the presence of five genotypes. Restriction fragment length polymorphism analysis, using a degenerate primer pair designed to amplify a segment (about 640 bp in length) of the recA gene from several members of the Enterobacteriaceae with restriction enzymes, HhaI and Sau3AI, showed that the resulting fragments could differentiate the isolates into three groups, respectively. CONCLUSION: recA gene amplification and HhaI and Sau3AI restriction digestion was demonstrated to increase the differentiating power between isolates of Salmonella enteritidis phage type 4 by combining the patterns of the random amplified polymorphic DNA analysis procedure using a primer ERIC2. SIGNIFICANCE AND IMPACT OF THE STUDY: A novel restriction fragment length polymorphism assay for isolates of Salmonella enteritidis phage type 4, based on the amplification of the recA gene was attained and its comparison and its combination with random amplified polymorphic DNA analysis was provided.

Bacterial Proteins↗
PubMed2001

Long-term preservation of strains of Burkholderia cepacia, Pseudomonas spp. and Stenotrophomonas maltophilia isolated from patients with cystic fibrosis.

Long-term preservation methods are important in the maintenance of bacteria for downstream research applications. Most clinical laboratories have only limited resources for archiving isolates and therefore require cost-effective and simple methods. An effective and cheap storage method using debrinated blood and maintenance at -80 degrees C is described.

Bacteriological Techniques↗
PubMed2001

Rapid characterization of the genomovars of the Burkholderia cepacia complex by PCR-single-stranded conformational polymorphism (PCR-SSCP) analysis.

Four polymerase chain reaction (PCR) primer pairs (A-D), specific for the Burkholderia cepacia complex of organisms were designed to encompass the entire gene (approximately 1300 bp) from sequence alignments of the rec A operon of B. cepacia. Genomic bacterial DNA from type strains and wild-type B. cepacia complex isolates of previously determined genomovar status was amplified employing these four primer pairs, as well as a fifth primer set (E) already published. Primer sets B, C and E were successful in obtaining a PCR amplicon of correct estimated size of 598, 1107 and 1043 bp, respectively. Subsequent single-stranded conformational polymorphism (SSCP) analysis of PCR amplicons demonstrated unique profiles for the five genomovar types for primer pairs B and E, but was unable to differentiate distinguishable profile types for primer pair C. SSCP analysis was demonstrated to be simple, rapid and cost effective and may prove a useful method of genomovar typing of B. cepacia complex organisms from cystic fibrosis patients in busy diagnostic laboratories.

Burkholderia cepacia↗
PubMed2001

Ocular surface reconstruction in LOGIC syndrome by amniotic membrane transplantation.

PURPOSE: To determine whether preserved amniotic membrane can be used to reconstruct the ocular surface after excision of the invading granulation material typical of LOGIC syndrome (laryngeal and ocular granulation tissue in children from the Indian subcontinent). METHODS: Granulation tissue was dissected and excised from both eyes of a 10-year-old boy with LOGIC syndrome. This procedure was followed by coverage of the corneal, scleral, and subtarsal regions of each eye with amniotic membrane, which had been stored for 6 months at -70 degrees C. RESULTS: Initial 2.5-month follow up demonstrated complete disappearance of granulation tissue. The fornices were patent, there was no recurrence of symblepharon, ocular inflammation was suppressed, and the patient reported markedly increased comfort. Both eyelids remained ptotic because of levator muscle atrophy secondary to many years of inability to open either eye. No residual scarring or evidence of granulation tissue was observed in that period. The 10-month follow up demonstrated limited recurrence, particularly where there was an intraoperative break in the amniotic membrane. CONCLUSIONS: After 24 operations to treat the ocular complications induced by LOGIC syndrome, amniotic membrane transplantation was the first effective treatment. In the early follow up period (2-3 months), there was complete cessation of the proliferation of granulation tissue and reepithelialization of the corneal surface. Longer follow up (10 months) demonstrated limited recurrence, which will require retreatment.

Amnion↗
PubMed2001

Frequency dependence of dynamic curvature effects on flow through coronary arteries.

The flow through a curved tube model of a coronary artery was investigated computationally to determine the importance of time-varying curvature on flow patterns that have been associated with the development of atherosclerosis. The entry to the tube was fixed while the radius of curvature varied sinusoidally in time at a frequency of 1 or 5 Hz. Angiographic data from other studies suggest that the radius of curvature waveform contains significant spectral content up to 6 Hz. The overall flow patterns were similar to those observed in stationary curved tubes; velocity profile skewed toward the outer wall, secondary flow patterns, etc. The effects of time-varying curvature on the changes in wall shear rate were expressed by normalizing the wall shear rate amplitude with the shear rate calculated at the static mean radius of curvature. It was found that the wall shear rate varied as much as 94 percent of the mean wall shear rate at the mid wall of curvature for a mean curvature ratio of 0.08 and a 50 percent change in radius of curvature. The effects of 5 Hz deformation were not well predicted by a quasi-static approach. The maximum values of the normalized inner wall shear rate amplitude were found to scale well with a dimensionless parameter equivalent to the product of the mean curvature ratio (delta), normalized change in radius of curvature (epsilon), and a Womersley parameter (alpha). This parameter was less successful at predicting the amplitudes elsewhere in the tube, thus additional studies are necessary. The mean wall shear rate was well predicted with a static geometry. These results indicate that dynamic curvature plays an important role in determining the inner wall shear rates in coronary arteries that are subjected to deformation levels of epsilon delta alpha > 0.05. The effects were not always predictable with a quasi-static approach. These results provide guidelines for constructing more realistic models of coronary artery flow for atherogenesis research.

Blood Flow Velocity↗
PubMed2001

PCR-based detection and identification of Burkholderia cepacia complex pathogens in sputum from cystic fibrosis patients.

PCR amplification of the recA gene followed by restriction fragment length polymorphism (RFLP) analysis was investigated for the rapid detection and identification of Burkholderia cepacia complex genomovars directly from sputum. Successful amplification of the B. cepacia complex recA gene from cystic fibrosis (CF) patient sputum samples containing B. cepacia genomovar I, Burkholderia multivorans, B. cepacia genomovar III, Burkholderia stabilis, and Burkholderia vietnamiensis was demonstrated. In addition, the genomovar identifications determined directly from sputum were the same as those obtained after selective culturing. Sensitivity experiments revealed that recA-based PCR could reliably detect B. cepacia complex organisms to concentrations of 10(6) CFU g of sputum(-1). To fully assess the diagnostic value of the method, sputum samples from 100 CF patients were screened for B. cepacia complex infection by selective culturing and recA-based PCR. Selective culturing identified 19 samples with presumptive B. cepacia complex infection, which was corroborated by phenotypic analyses. Of the culture-positive sputum samples, 17 were also detected directly by recA-based PCR, while 2 samples were negative. The isolates cultured from both recA-negative sputum samples were subsequently identified as Burkholderia gladioli. RFLP analysis of the recA amplicons revealed 2 patients (12%) infected with B. multivorans, 11 patients (65%) infected with B. cepacia genomovar III-A, and 4 patients (23%) infected with B. cepacia genomovar III-B. These results demonstrate the potential of recA-based PCR-RFLP analysis for the rapid detection and identification of B. cepacia complex genomovars directly from sputum. Where the sensitivity of the assay proves a limitation, sputum samples can be analyzed by selective culturing followed by recA-based analysis of the isolate.

Adolescent↗
PubMed2001

Improved cultural detection of Burkholderia cepacia from sputum in patients with cystic fibrosis.

AIMS: To evaluate the sensitivity and specificity of two selective media for the isolation of Burkholderia cepacia from sputum specimens in patients with cystic fibrosis (CF). METHODS: In total, 149 expectorated sputum specimens from 113 patients with CF (32 cepacia colonised patients and 81 non-cepacia colonised patients) attending three CF centres were examined for the presence of B cepacia on two selective media: (1) MAST selective agar, a commercially available selective medium widely used in the UK and (2) BCSA (B cepacia selective agar), a new medium recently described, which is used predominantly in North America. RESULTS: Burkholderia cepacia was isolated from 53 of 149 (35.6%) specimens examined, representing 32 of 113 (28.3%) patients, using both the MAST and BCSA media. Growth was most rapid on BCSA with all (53 of 53) isolates detectable after 48 hours, compared with 50 of the 53 isolates on MAST agar, with the remaining three isolates detectable at five days. Twenty eight contaminants were identified on MAST agar and 13 on BCSA agar; mainly Alcaligenes xylosoxidans and yeast on MAST agar and Flavobacterium indologenes on BCSA medium. BCSA was equivalent to MAST agar in its ability to isolate B cepacia from patients with CF with a history of B cepacia infection. CONCLUSIONS: The increased selectivity and reduced time to detection of BCSA makes it an attractive alternative to MAST. However, its present limited commercial availability in the UK may delay its use in routine diagnostic laboratories because of complications with media preparation and quality control.

Adult↗