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Biomedical subjects

M Bradley

Publications and source records attributed to M Bradley.

At least 19 recordsLinked to original sources
PubMed2002

Susceptibility loci for atopic dermatitis on chromosomes 3, 13, 15, 17 and 18 in a Swedish population.

Atopic dermatitis is a hereditary, pruritic, inflammatory and chronic skin disease that typically presents in early childhood and may continue or recur later. The etiology of atopic dermatitis is unknown, but several lines of evidence indicate that it is a multifactorial disorder caused by the combined influence of genetic and environmental factors, even though the relative contributions of genes and environment are not known. To identify important loci that contribute to the development of atopic dermatitis, we conducted a genome-wide linkage analysis with 367 microsatellite markers, using a non-parametric affected relative-pair method in 109 pedigrees. Three qualitative phenotypes and one semi-quantitative phenotype were studied. For the phenotype atopic dermatitis, linkage to chromosome region 3p24-22 was found. For another phenotype, atopic dermatitis combined with raised allergen-specific IgE levels, a suggestive linkage was found to chromosome region 18q21. For the semi-quantitative phenotype severity score of atopic dermatitis, suggestive linkage was found to chromosome regions 3q14, 13q14, 15q14-15 and 17q21. Identifying chromosome regions linked to susceptibility genes for atopic dermatitis provides a platform from which the search for atopic dermatitis genes can proceed.

Chromosome Mapping↗
PubMed2002

Analysis of association and linkage for the interleukin-4 and interleukin-4 receptor b;alpha; regions in Swedish atopic dermatitis families.

BACKGROUND: Atopic dermatitis (AD) is caused by genetic and environmental factors that interact to determine disease susceptibility and severity. Several lines of evidence suggest that the IL-4 gene and the IL-4-receptor alpha (IL-4Ralpha) gene are involved in the development of atopic diseases. OBJECTIVE: The objective of this study was to evaluate the possible involvement of the chromosomal regions 5q31 and 16p12, which include the genes coding for the IL-4 and the IL-4Ralpha in AD. METHODS: We conducted linkage analysis and association studies using the microsatellite markers D16S298 and D16S403 and a single nucleotide polymorphism in the promoter region of the IL-4 gene (- 590C/T) in 406 Swedish families with at least two siblings affected with AD, in total 1514 individuals. RESULTS AND CONCLUSION: We report linkage (P < 0.005) to the - 590C/T polymorphism in the promoter of the IL-4 gene for the semiquantitative trait severity score of AD. Neither linkage nor association was found to the IL-4Ralpha chromosomal region.

Chromosome Mapping↗
PubMed2002

Clinical and genetic studies of Birt-Hogg-Dubé syndrome.

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant cancer syndrome characterised by benign skin tumours, renal tumours, and spontaneous pneumothorax. The gene has been mapped to chromosome 17p11.2 and recently identified, expressing a novel protein called folliculin. We report the clinical and genetic studies of four sporadic BHD cases and four families with a total of 23 affected subjects. Haplotype analysis of these families using BHD linked markers showed they did not share the same affected alleles, excluding common ancestry. Mutation analysis of the BHD gene identified two germline mutations on exon 11 (c.1733insC and c.1733delC) in three of four families as well as two of four sporadic cases. A novel somatic mutation, c.1732delTCinsAC, was detected in a BHD related chromophobe renal carcinoma. Our results confirmed the (C)8 tract in exon 11 as a mutational hot spot in BHD and should always be considered for future genetic testing. Our observation also indicated that the second hit (of Knudson's two hit theory) in some BHD related tumours is in the form of somatic mutation rather than LOH. In a large French family in which eight affected subjects carry the c.1733delC mutation, a phenocopy who has multiple episodes of spontaneous pneumothorax was identified. A total of five mutation carriers (aged between 37 to 66) did not have any evidence of BHD features, suggesting either reduced penetrance or late age of onset of the disease. In addition, six out of eight affected subjects who have positive germline mutation have confirmed neoplastic colonic polyps, indicating that colorectal neoplasia is an associated feature of BHD in some families. Our studies have observed several interesting genetic features in BHD: (1) the poly (C) tract in exon 11 as a mutational hot spot; (2) the existence of phenocopy; (3) reduced penetrance or late age of onset of disease; (4) association with colorectal neoplasia in some families; and (5) somatic mutation instead of LOH as the second hit in BHD tumours.

Adult↗
PubMed2002

Effective and culturally acceptable water storage in Zimbabwe: maintaining the quality of water abstracted from upgraded family wells.

Because domestic water can be a vehicle of disease transmission in the home, there is a need for intervention. In Zimbabwe. 60 rural households obtaining water from shallow wells were selected for a field study. A water urn was designed, pretested, and field-tested. Thirty households designated as the case group were given two water urns each to substitute for traditional water storage containers (paint containers, oil containers, etc.). The remaining 30 households served as a control group. Samples were collected twice, at two-week intervals, from the water supply source (upgraded family wells) and storage containers (water urn or traditional containers) of each household (228 samples). Total coliform bacteria and fecal coliform bacteria were enumerated with the membrane filtration technique. A pretest of the water urn design showed a decline in turbidity that corresponded with a decline in bacterial counts. Wells supplying the case households had higher bacterial counts than those supplying the control households, but bacterial loads in the water urns were significantly lower than those observed in the corresponding supply wells (paired t-test: t = 3.97, df = 55, p < .01). Bacterial loads in traditional containers were similar to those observed in the supply wells (paired t-test; t = 0.2, df = 57, p > .05). The case group eagerly substituted water urns for traditional containers. The use of water urns was found to prevent or to reduce further contamination of well water after collection.

Disease Transmission, Infectious↗
PubMed2001

Site distribution in resin beads as determined by confocal Raman spectroscopy.

Scanning confocal Raman spectroscopy was used to study the distribution of reactive sites within a resin bead used for solid-phase synthesis. The distribution of NH2 groups in aminomethylated polystyrene resin (APS) was determined by doping with varying amounts of 4-cyanobenzoic acid. The extent of loading was determined by both elemental analysis and ninhydrin assays. The spatial distribution of the coupled 4-cyanobenzamide within the bead was determined to an in-plane resolution of 1 microm and depth resolution of about 4 microm, using the strong Raman CN stretching vibrational transition at 2230 cm(-1). Dry and swollen beads were studied and the distribution was found to be essentially uniform throughout the bead in all cases.

Journal Article↗
PubMed2001

Birt-Hogg-Dubé syndrome: mapping of a novel hereditary neoplasia gene to chromosome 17p12-q11.2.

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant neoplasia syndrome characterized mainly by benign skin tumors, and to a lesser extent, renal tumors and spontaneous pneumothorax. To map the BHD locus, we performed a genome-wide linkage analysis using polymorphic microsatellite markers on a large Swedish BHD family. Evidence of linkage was identified on chromosome 17p12-q11.2, with a maximum LOD score of 3.58 for marker D17S1852. Further haplotype analysis defined a approximately 35 cM candidate interval between the two flanking markers, D17S1791 and D17S798. This information will facilitate the identification of the BHD gene, leading to the understanding of its underlying molecular etiology.

Carcinoma, Renal Cell↗
PubMed2001

Linkage and association to candidate regions in Swedish atopic dermatitis families.

We have studied, in 406 families with at least two siblings affected with atopic dermatitis (in total 1514 individuals) from the Swedish population, linkage and association to five chromosomal regions (2q35, 5q31-33, 6p21, 11q13 and 14q11) previously implicated in atopic diseases. The region on 14q11 gave evidence for linkage to atopic dermatitis (NPL-score: 2.36, P<0.009). In the 11q13 region, there was a clear association to an intragenic marker in the beta-subunit of the high-affinity IgE receptor for raised allergen-specific serum IgE levels (P<0.009). When a quantitative variable for the severity of atopic dermatitis was studied, evidence was found in favour of linkage to the 5q31-33 region, with the highest Z-score (2.06) close to the marker D5S458 (P<0.005).

Age of Onset↗
PubMed2001

In-vitro visualization of biopsy needles with ultrasound: a comparative study of standard and echogenic needles using an ultrasound phantom.

AIM: To demonstrate the circumstances where echogenically enhanced biopsy needles confer an increase in visualization during ultrasound-guided biopsy using an in-vitro experiment. MATERIALS AND METHODS: An experiment using both standard and echogenically enhanced needles was conducted in a purpose built interventional phantom. The needle tip echogenicity and shaft visualization was recorded at different angles (20 and 60 degrees ) between the ultrasound probe and needle. The needle tip echogenicity was also recorded in four different angles of bevel rotation. The experiment was performed using a total of 18 different needles of 18 and 20 gauge. RESULTS: The experiment confirmed some previous findings. The needle was better visualised at an angle of approximately 60 degrees to the probe. The needle tip was optimally visualized with the bevel facing the transducer or 180 degrees to it. Needle tip movement improved conspicuity. Using an optimal angle of approach (60 degrees ) the use of an echogenic needle did not confer any increase in conspicuity. If the transducer to needle angle was suboptimal (20 degrees ) then there was increased visualization of some echogenically enhanced needles. CONCLUSION: Optimisation of the conditions prior to ultrasound-guided needle biopsy will increase the visualization of the chosen device thus aiding the interventionalist. Needle gauge, bevel position, movement of the needle and the probe to needle angle all affect conspicuity. Needle coating or roughening does not improve tip visualization if the angle between the needle and probe can be optimized (60 degrees ). In unfavourable situations when the angle is suboptimal (20 degrees ), we have shown that echogenic enhancement of the needle tip can make it more visible.

Biopsy, Needle↗
PubMed2001

Physician perceptions of a national formulary.

OBJECTIVE: To assess the perceptions of US Department of Veterans Affairs (VA) physicians regarding effects of a National Formulary (NF) on patient care, access to drugs, physician workload, and resident training approximately 1 year after it was implemented. STUDY DESIGN: Cross-sectional survey. METHODS: A questionnaire was sent to attending physicians working within the VA healthcare system. Participants included general internists (n = 2824), neurologists (n = 238), psychiatrists (n = 997), general surgeons (n = 429), and urologists (n = 152). The response rate was 45%. RESULTS: Most physicians (63%) thought that they could prescribe needed drugs; 65% agreed that patients could obtain needed nonformulary drugs. One third disagreed that access to prescription pharmaceuticals had increased; 29% stated the NF impinged on providing quality care to their own patients, and 21% thought it did so to patients from other VA facilities. Thirty eight percent of physicians perceived the NF to be more restrictive than private sector formularies; 16% thought that the NF diminished the ability to train residents for managed care. Forty percent thought that the NF added to workload. Generalists more often perceived that the NF improved their ability to provide care compared with neurologists (27% vs 18%, P = .046), psychiatrists (27% vs 22%, P = .027), and internal medicine subspecialists (27% vs 18%, P = .001). Physicians with more clinic time were more likely to perceive that the NF increased workload. CONCLUSION: Although differences of opinions among physicians were noted, most responding VA physicians did not perceive that the NF adversely affected patient care, access to pharmaceuticals, physician workload, or resident training.

Attitude of Health Personnel↗
PubMed2000

Optimising inhibitors of trypanothione reductase using solid-phase chemistry.

A series of inhibitors of the enzyme trypanothione reductase has been identified using directed solid-phase chemistry. The compounds were based on a series of polyamine scaffolds and used the natural product kukoamine A as the lead structure. A compound with a Ki of 76 nM was identified, although somewhat surprisingly the compound appeared to be noncompetitive in nature.

Animals↗
PubMed2000

Systematic review of water fluoridation.

OBJECTIVE: To review the safety and efficacy of fluoridation of drinking water. DESIGN: Search of 25 electronic databases and world wide web. Relevant journals hand searched; further information requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. MAIN OUTCOME MEASURES: Decayed, missing, and filled primary/permanent teeth. Proportion of children without caries. Measure of effect was the difference in change in prevalence of caries from baseline to final examination in fluoridated compared with control areas. For potential adverse effects, all outcomes reported were used. RESULTS: 214 studies were included. The quality of studies was low to moderate. Water fluoridation was associated with an increased proportion of children without caries and a reduction in the number of teeth affected by caries. The range (median) of mean differences in the proportion of children without caries was -5.0% to 64% (14.6%). The range (median) of mean change in decayed, missing, and filled primary/permanent teeth was 0.5 to 4.4 (2.25) teeth. A dose-dependent increase in dental fluorosis was found. At a fluoride level of 1 ppm an estimated 12.5% (95% confidence interval 7.0% to 21.5%) of exposed people would have fluorosis that they would find aesthetically concerning. CONCLUSIONS: The evidence of a beneficial reduction in caries should be considered together with the increased prevalence of dental fluorosis. There was no clear evidence of other potential adverse effects.

Child↗
PubMed2000

Biomimetic synthesis of lantibiotics.

The lantibiotics are a class of highly posttranslationally modified small peptide antibiotics containing numerous lanthionine and dehydroamino acid residues. We have prepared peptides containing multiple dehydroamino acids and cysteine residues in order to probe the biomimetic synthesis of the lantibiotics from their precursor peptides. A novel synthetic methodology was developed to allow the synthesis of multiple dehydroamino acid containing peptides. Cyclisations were rapid, quantitative and regiospecific. Remarkably the peptide sequences alone appear to contain sufficient information to direct a series of stereo- and regiospecific ring closures. Thus both the two linear peptides for the B and E-rings closed stereoselectively. In the case of the A-ring precursor peptide which contained two dehydroamino acids, cyclisation was again totally regioselective, although not totally stereoselective.

Alanine↗
PubMed2000

Polymer-based materials to be used as the active element in microsensors: a scanning force microscopy study

Polymer-based materials can be incorporated as the active sensing elements in chemiresistor devices. Most of these devices take advantage of the fact that certain polymers will swell when exposed to gaseous analytes. To measure this response, a conducting material such as carbon black is incorporated within the nonconducting polymer matrix. In response to analytes, polymer swelling results in a measurable change in the conductivity of the polymer/carbon composite material. Arrays of these sensors may be used in conjunction with pattern recognition techniques for purposes of analyte recognition and quantification. We have used the technique of scanning force microscopy (SFM) to investigate microstructural changes in carbon-polymer composites formed from the polymers poly (isobutylene) (PIB), poly (vinyl alcohol) (PVA), and poly (ethylene-vinyl acetate) (PEVA) when exposed to the analytes hexane, toluene, water, ethanol, and acetone. Using phase-contrast imaging (PI), changes in the carbon nanoparticle distribution on the surface of the polymer matrix are measured as the polymers are exposed to the analytes in vapor phase. In some but not all cases, the changes were reversible (at the scale of the SFM measurements) upon removal of the analyte vapor. In this paper, we also describe a new type of microsensor based on piezoresistive microcantilever technology. With these new devices, polymeric volume changes accompanying exposure to analyte vapor are measured directly by a piezoresistive microcantilever in direct contact with the polymer. These devices may offer a number of advantages over standard chemiresistor-based sensors.

Journal Article↗