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Biomedical subjects

R Evans

Publications and source records attributed to R Evans.

At least 19 recordsLinked to original sources
PubMed2007

Model colloidal fluid with competing interactions: bulk and interfacial properties.

Using a simple mean field density functional theory (DFT), the authors investigate the structure and phase behavior of a model colloidal fluid composed of particles interacting via a pair potential which has a hard core of diameter sigma, is attractive Yukawa at intermediate separations, and is repulsive Yukawa at large separations. The authors analyze the form of the asymptotic decay of the bulk fluid correlation functions, comparing results from DFT with those from the self-consistent Ornstein-Zernike approximation (SCOZA). In both theories the authors find rich crossover behavior, whereby the ultimate decay of correlation functions changes from monotonic to long wavelength damped oscillatory decay on crossing certain lines in the phase diagram or sometimes from oscillatory to oscillatory with a longer wavelength. For some choices of potential parameters the authors find, within the DFT, a lambda line at which the fluid becomes unstable with respect to periodic density fluctuations. SCOZA fails to yield solutions for state points near such a lambda line. The propensity towards clustering of particles, which is reflected by the presence of a long wavelength (>>sigma) slowly decaying oscillatory pair correlation function, and a structure factor that exhibits a very sharp maximum at small but nonzero wave numbers, is enhanced in states near the lambda line. The authors present density profiles for the planar liquid-gas interface and for fluids adsorbed at a planar hard wall. The presence of a nearby lambda transition gives rise to pronounced long wavelength oscillations in the one-body density profiles at both types of interface.

Journal Article↗
PubMed2007

The use of local isolates in Western blots improves serological diagnosis of Lyme disease in Scotland.

Nine Scottish Borrelia burgdorferi isolates were investigated in IgG Western blot tests. Sera previously found to be positive and negative when tested by routine Western blots prepared from reference strain B. burgdorferi sensu stricto antigen had different outcomes with these isolates. Two isolates, E5 (Borrelia afzelii) and G4 (B. burgdorferi sensu stricto) performed well, reproducing Western blot-positive results in 90 and 95% of tests, respectively. When antigens from both isolates were incorporated into a single IgG Western blot, the results of a panel of sera were improved when compared to the routine reference strain IgG Western blot. All of the sera positive by the routine Western blot remained positive using the Scottish isolate antigen mix. Twenty-three of the 25 negative sera remained negative and two produced an equivocal result. Of the 15 samples that tested IgG Western blot equivocal with the B. burgdorferi sensu stricto reference strain, 11 (73%) became weak or strong positive when tested with the B. afzelii/B. burgdorferi sensu stricto antigen mix (chi(2)=14.35, Yates' correction, P<0.001). In seven of these, a clinical picture of Lyme disease was consistent with the new results. The use of Scottish strains of B. afzelii and B. burgdorferi sensu stricto to provide antigen for the IgG Western blot improves the diagnosis of Lyme disease for patients in Scotland.

Antibodies, Bacterial↗
PubMed2006

Personalised risk communication for informed decision making about taking screening tests.

BACKGROUND: There is a trend towards greater patient involvement in healthcare decisions. Adequate discussion of the risks and benefits associated with different choices is often required if involvement is to be genuine and effective. Achieving both the adequate involvement of consumers and informed decision making are now seen as important goals for any screening programme. Personalised risk estimates have been shown to be effective methods of risk communication in general, but the effectiveness of different strategies has not previously been examined. OBJECTIVES: To assess the effects of different types of personalised risk communication for consumers making decisions about taking screening tests. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2004), MEDLINE (1985 to December 2005), EMBASE (1985 to December 2005), CINAHL (1985 to December 2005), and PsycINFO (1989 to December 2005). Follow-up searches involved hand searching Preventive Medicine, citation searches on seven authors, and searching reference lists of articles. For the original version of this review (Edwards 2003c) we also searched CancerLit (1985 to 2001) and Science Citation Index Expanded (searched March 2002). SELECTION CRITERIA: Randomised controlled trials addressing the decision by consumers of whether or not to undergo screening, incorporating an intervention with a 'personalised risk communication element' and reporting cognitive, affective, or behavioural outcomes. A 'personalised risk communication element' is based on the individual's own risk factors for a condition (such as age or family history). It may be calculated from an individual's risk factors using formulae derived from epidemiological data, and presented as an absolute or relative risk or as a risk score, or it may be categorised into, for example, high, medium or low risk groups. It may be less detailed still, involving a listing, for example, of a consumer's risk factors as a focus for discussion and intervention. DATA COLLECTION AND ANALYSIS: Two authors independently assessed each trial for quality and extracted data. We extracted data about the nature and setting of the intervention, and relevant outcome data, along with items relating to methodological quality. We then used standard statistical methods of the Consumers and Communication Review Group to combine data using MetaView, including analysis according to different levels of detail of personalised risk communication, different condition for screening, and studies based only on high risk participants rather than people at 'average' risk. MAIN RESULTS: Twenty-two studies were included, nine of which were added in the 2006 update of this review. There was weak evidence, consistent with a small effect, that personalised risk communication (whether written, spoken or visually presented) increases uptake of screening tests (odds ratio (OR) 1.31 (random effects, 95% confidence interval (CI) 0.98 to 1.77). In three studies the interventions showed a trend towards more accurate risk perception (OR 1.65 (95% CI 0.96 to 2.81), and three other trials with heterogenous outcome measures showed improvements in knowledge with personalised risk interventions. There was little other evidence from these studies that the interventions promoted or achieved informed decision making by consumers about participation in screening. More detailed personalised risk communication may be associated with a smaller increase in uptake of tests. That is, for personalised risk communication which used and presented numerical calculations of risk, the OR for test uptake was 0.82 (95% CI 0.65 to 1.03). For risk estimates or calculations which were categorised into high, medium or low strata of risk, the OR was 1.42 (95% CI 1.07 to 1.89). For risk communication that simply listed personal risk factors the OR was 1.42 (95% CI 0.95 to 2.12). Over half of the included studies assessed interventions in the context of mammography. These studies showed similar effects to the overall dataset. The five studies examining risk communication in high risk individuals (individuals at higher risk due to, for example, a family history of breast cancer or other conditions) showed larger odds ratios for uptake of tests than the other studies (random effects OR 1.74; 95% CI 1.05 to 2.88). There were insufficient data from the included studies to report odds ratios on other key outcomes such as: intention to take tests, anxiety, satisfaction with decisions, decisional conflict, knowledge and resource use. AUTHORS' CONCLUSIONS: Personalised risk communication (as currently implemented in the included studies) may have a small effect on increasing uptake of screening tests, and there is only limited evidence that the interventions have promoted or achieved informed decision making by consumers.

Communication↗
PubMed2006

Screening in Yukawa fluid mixtures.

The effective pair potential between mesoscopic charged particles in a neutralizing background medium takes a Yukawa form exp(-lambda r)/r with screening length lambda(-1). We consider a dilute suspension of such Yukawa particles dispersed in a solvent with correlation length xi<lambda(-1) and show that the Yukawa interaction is screened if the pair potentials between solvent particles exhibit Yukawa decay with the same screening length lambda(-1). However, if the solvent pair potentials are shorter ranged than the solute Yukawa potentials, then the effective potential between pairs of solute particles is unscreened, i.e., the effective potential between the solute particles is equal to the bare potential at large particle separations.

Journal Article↗
PubMed2006

Human LBP-32/MGR is a repressor of the P450scc in human choriocarcinoma cell line JEG-3.

Steroid hormones regulate a wide range of physiologic functions in humans. The cholesterol side-chain cleavage enzyme P450scc regulates the initial step of biosynthesis of all steroid hormones. We investigated the expression of P450scc by studying a potential regulator of P450scc, LBP-32/MGR. Using a Northern blot, we found that LBP-32/MGR mRNA was expressed mainly in the human placenta. Using radiation hybrid mapping, we identified LBP-32/MGR on human chromosome 2p25. Recombinant LBP-32/MGR protein bound preferentially to a DNA fragment from the promoter of P450scc in vitro and exhibited clear nuclear localization in transfected cells. Luciferase reporter gene assays showed that LBP-32/MGR specifically repressed transcriptional activation of the human P450scc promoter. Because placental P450scc expression is essential for pregnancy and steroid biosynthesis, the placental expression and transcriptional repressor activity of LBP-32/MGR in JEG-3 cells suggest it has a role as a transcriptional modulator of steroid biosynthesis.

Cell Line, Transformed↗
PubMed2006

The DNA sequence and biological annotation of human chromosome 1.

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Base Sequence↗
PubMed2006

The development of a semi-structured home interview (CHIF) to directly assess function in cognitively impaired elderly people in two cultures.

BACKGROUND: Assessing function is a crucial element in the diagnosis of dementia. This information is usually obtained from key informants. However, reliable informants are not always available. METHODS: A 10-item semi-structured home interview (the CHIF, or Clinician Home-based Interview to assess Function) to assess function primarily by measuring instrumental activities of daily living directly was developed and tested for inter-rater reliability and validity as part of the Indianapolis-Ibadan dementia project. The primary validity measurements were correlations between scores on the CHIF and independently gathered scores on the Blessed Dementia Scale (from informants) and the Mini-mental State Examination (MMSE). Sensitivities and specificities of scores on the CHIF and receiver operator characteristic (ROC) curves were constructed with dementia as the dependent variable. RESULTS: Inter-rater reliability for the CHIF was high (Pearson's correlation coefficient 0.99 in Indianapolis and 0.87 in Ibadan). Internal consistency, in both samples, was good (Cronbach's alpha 0.95 in Indianapolis and 0.83 in Ibadan). Scores on the CHIF correlated well with the Blessed Dementia scores at both sites (-0.71, p < 0.0001 for Indianapolis and -0.56, p < 0.0001 for Ibadan) and with the MMSE (0.75, p < 0.0001 for Indianapolis and 0.44, p < 0.0001 for Ibadan). For all items at both sites, the subjects without dementia performed significantly better than those with dementia. The area under the ROC curve for dementia diagnosis was 0.965 for Indianapolis and 0.925 for Ibadan. CONCLUSION: The CHIF is a useful instrument to assess function directly in elderly participants in international studies, particularly in the absence of reliable informants.

Activities of Daily Living↗
PubMed2006

Herbicidal inhibitors of amino acid biosynthesis and herbicide-tolerant crops.

Acetohydroxyacid synthase (AHAS) inhibitors interfere with branched-chain amino acid biosynthesis by inhibiting AHAS. Glyphosate affects aromatic amino acid biosynthesis by inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Glufosinate inhibits glutamine synthetase and blocks biosynthesis of glutamine. AHAS gene variants that confer tolerance to AHAS inhibitors have been discovered in plants through selection or mutagenesis. Imidazolinone-tolerant crops have been commercialized based on these AHAS gene variants. A modified maize EPSPS gene and CP4-EPSPS gene from Agrobacterium sp. have been used to transform plants for target-based tolerance to glyphosate. A gox gene isolated from Ochrobactrum anthropi has also been employed to encode glyphosate oxidoreductase to detoxify glyphosate in plants. Glyphosate-tolerant crops with EPSPS transgene alone or both EPSPS and gox transgenes have been commercialized. Similarly, bar and pat genes isolated from Streptomyces hygroscopicus and S. viridochromogenes, respectively, have been inserted into plants to encode phosphinothricin N-acetyltransferase to detoxify glufosinate. Glufosinate-tolerant crops have been commercialized using one of these two transgenes.

Adaptation, Physiological↗
PubMed2006

Pair-correlation functions and phase separation in a two-component point Yukawa fluid.

We investigate the structure of a binary mixture of particles interacting via purely repulsive point Yukawa pair potentials with a common inverse screening length lambda. Using the hypernetted chain closure to the Ornstein-Zernike equations, we find that for a system with "ideal" (Berthelot mixing rule) pair-potential parameters for the interaction between unlike species, the asymptotic decay of the total correlation functions crosses over from monotonic to damped oscillatory on increasing the fluid total density at fixed composition. This gives rise to a Kirkwood line in the phase diagram. We also consider a "nonideal" system, in which the Berthelot mixing rule is multiplied by a factor (1+delta). For any delta>0 the system exhibits fluid-fluid phase separation and remarkably the ultimate decay of the correlation functions is now monotonic for all (mixture) state points. Only in the limit of vanishing concentration of either species does one find oscillatory decay extending to r=infinity. In the nonideal case the simple random-phase approximation provides a good description of the phase separation and the accompanying Lifshitz line.

Journal Article↗
PubMed2006

Soft core fluid in a quenched matrix of soft core particles: a mobile mixture in a model gel.

We present a density-functional study of a binary phase-separating mixture of soft core particles immersed in a random matrix of quenched soft core particles of larger size. This is a model for a binary polymer mixture immersed in a cross-linked rigid polymer network. Using the replica "trick" for quenched-annealed mixtures we derive an explicit density functional theory that treats the quenched species on the level of its one-body density distribution. The relation to a set of effective external potentials acting on the annealed components is discussed. We relate matrix-induced condensation in bulk to the behavior of the mixture around a single large particle. The interfacial properties of the binary mixture at a surface of the quenched matrix display a rich interplay between capillary condensation inside the bulk matrix and wetting phenomena at the matrix surface.

Journal Article↗
PubMed2006

Cholesterol, APOE genotype, and Alzheimer disease: an epidemiologic study of Nigerian Yoruba.

OBJECTIVE: To examine the relationship between cholesterol and other lipids, APOE genotype, and risk of Alzheimer disease (AD) in a population-based study of elderly Yoruba living in Ibadan, Nigeria. METHODS: Blood samples and clinical data were collected from Yoruba study participants aged 70 years and older (N = 1,075) as part of the Indianapolis-Ibadan Dementia Project, a longitudinal epidemiologic study of AD. Cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride levels were measured in fasting blood samples. DNA was extracted and APOE was genotyped. Diagnoses of AD were made by consensus using National Institute of Neurologic Disorders/Stroke-Alzheimer's Disease and Related Disorders Association criteria. RESULTS: Logistic regression models showed interaction after adjusting for age and gender between APOE-epsilon4 genotype and biomarkers in the risk of AD cholesterol*genotype (p = 0.022), LDL*genotype (p= 0.018), and triglyceride*genotype (p = 0.036). Increasing levels of cholesterol and LDL were associated with increased risk of AD in individuals without the APOE-epsilon4 allele, but not in those with APOE-epsilon4. There was no significant association between levels of triglycerides and AD risk in those without APOE-epsilon4. CONCLUSIONS: There was a significant interaction between cholesterol, APOE-epsilon4, and the risk of Alzheimer disease (AD) in the Yoruba, a population that has lower cholesterol levels and lower incidence rates of AD compared to African Americans. APOE status needs to be considered when assessing the relationship between lipid levels and AD risk in population studies.

Aged↗
PubMed2006

Improvement in quality of life with infliximab induction and maintenance therapy in patients with moderate-to-severe psoriasis: a randomized controlled trial.

BACKGROUND: Psoriasis has a well-documented, markedly negative effect on patient quality of life. OBJECTIVES: To evaluate the impact of long-term infliximab maintenance therapy on health-related quality of life (HRQoL) in patients with psoriasis. METHODS: The Dermatology Life Quality Index (DLQI) and 36-item Short Form Health Survey (SF-36) were administered as part of the pivotal double-blind, placebo-controlled efficacy and safety EXPRESS study of infliximab in chronic plaque psoriasis. In total, 378 patients with moderate-to-severe psoriasis were enrolled at 32 centres in Europe and Canada. Patients were randomized to receive either placebo or infliximab 5 mg kg(-1) induction at weeks 0, 2 and 6 followed by maintenance every 8 weeks; placebo patients crossed over at week 24 to receive the infliximab induction and maintenance regimen. RESULTS: At week 10, infliximab-treated patients had significantly greater improvement in DLQI scores (P < 0.001) and SF-36 physical and mental component summary scores (P < 0.001) than placebo-treated patients. Significant improvement (P < 0.001) was also seen in all eight SF-36 subscales, and was greatest for the "Bodily Pain" and "Social Functioning" scales. Significant improvement in HRQoL persisted with maintenance infliximab treatment at week 24 (P < 0.001), with patients achieving a Psoriasis Area and Severity Index score of 0 reporting the greatest benefit. Treatment-related HRQoL improvement remained substantial at week 50. CONCLUSIONS: Infliximab induction and maintenance regimens resulted in rapid, substantial, sustained and clinically meaningful improvement in both dermatology-specific and general quality of life indices in patients with psoriasis, with total clearance resulting in maximum improvement.

Adult↗