Search PubMed⌕ Search

Biomedical subjects

R Evans

Publications and source records attributed to R Evans.

At least 73 records · Page 4Linked to original sources
PubMed2002

Urinary tract ultrasonography in the evaluation of haematuria--a report of over 1,000 cases.

Over a 5-year period, 1007 patients with haematuria were investigated, using a protocol based on ultrasonography as the upper tract imaging modality of choice. Intravenous urography (IVU) was only used in selected individuals, including those patients with bladder cancer suspected on cystoscopy, suspicious or malignant cytology, previous investigation for haematuria, on-going haematuria at the time of their clinic visit, a history of flank pain or hydronephrosis on ultrasonography. Of this series, 840 (83%) had visible haematuria, 158 (15%) had microscopic or chemical haematuria and 9 (0.9%) had unspecified haematuria. A total of 133 bladder transitional cell tumours, 21 renal cell cancers and 2 upper tract transitional cell cancers (TCC) were diagnosed. The sensitivity of ultrasound with respect to bladder cancer was 63% and the specificity 99%. The odds ratio of diagnosing cancer in patients with visible haematuria compared to microscopic or unspecified haematuria was 3.3. No upper tract tumours were missed using this investigational protocol. An ultrasonography-based protocol could miss fewer upper tract TCCs than a standard IVU-based service would miss renal cell cancer. Provided there is no history of flank pain, no malignant cytology, no hydronephrosis and no previously investigated haematuria, IVU could be safely omitted.

Carcinoma, Renal Cell↗
PubMed2001

Activator-mediated disruption of sequence-specific DNA contacts by the general transcription factor TFIIB.

The transcription factor TFIIB plays a central role in preinitiation complex assembly, providing a bridge between promoter-bound TFIID and RNA Polymerase II. TFIIB possesses sequence-specific DNA-binding ability and interacts with the TFIIB-recognition element (BRE), present in many promoters. Here we show that the BRE suppresses the basal level of transcription elicited by a core promoter, which increases the amplitude of transcriptional stimulation in the presence of an activator protein. Further, we find that an activator can disrupt the TFIIB-BRE interaction within a promoter-bound complex. Our results reveal a novel function for activators in the modulation of core promoter recognition by TFIIB.

Adenoviridae↗
PubMed2001

Prevalence of cognitive impairment: data from the Indianapolis Study of Health and Aging.

BACKGROUND: The epidemiology and natural history of cognitive impairment that is not dementia is important to the understanding of normal aging and dementia. OBJECTIVE: To determine the prevalence and outcome of cognitive impairment that is not dementia in an elderly African American population. METHOD: A two-phase, longitudinal study of aging and dementia. A total of 2212 community-dwelling African American residents of Indianapolis, IN, aged 65 and older were screened, and a subset (n = 351) received full clinical assessment and diagnosis. Subsets of the clinically assessed were seen again for clinical assessment and rediagnosis at 18 and 48 months. Weighted logistic regression was used to generate age-specific prevalence estimates. RESULTS: The overall rate of cognitive impairment among community-dwelling elderly was 23.4%. Age-specific rates indicate increasing prevalence with increasing age: 19.2% for ages 65 to 74 years, 27.6% for ages 75 to 84 years, and 38.0% for ages 85+ years. The most frequent cause of cognitive impairment was medically unexplained memory loss with a community prevalence of 12.5%, followed by medical illness-associated cognitive impairment (4.0% prevalence), stroke (3.6% prevalence), and alcohol abuse (1.5% prevalence). At 18-month follow-up, 26% (17/66) of the subjects had become demented. CONCLUSIONS: Cognitive impairment short of dementia affects nearly one in four community-dwelling elders and is a major risk factor for later development of dementia.

Age Distribution↗
PubMed2001

Near-critical confined fluids and Ising films: density-matrix renormalization-group study.

Two-dimensional Ising strips subject to identical surface fields h(1)=h(2) > or =0 are studied for temperatures above and below the bulk critical temperature T(c) and a range of bulk fields h by means of the density-matrix renormalization-group method. In the case of nonvanishing surface fields, the near-critical behavior of the solvation force f(solv), total adsorption Gamma, inverse longitudinal correlation length xi(parallel)( -1) and specific heat C(H) is strongly influenced by the (pseudo) capillary condensation that occurs below T(c). We obtain scaling functions of f(solv), Gamma, and xi(parallel)(-1). C(H) exhibits a weakly rounded singularity on crossing the pseudocoexistence line. We contrast these results with those for the case of free boundaries where, for temperatures slightly below T(c), f(solv) and C(H) exhibit a sharp extremum away from h=0. Our results have direct repercussions for the properties of near-critical Ising films in three dimensions and we argue that the long-ranged solvation (Casimir) force in confined fluids should be more attractive in the neighborhood of the capillary critical point than exactly at the bulk critical point.

Journal Article↗
PubMed2001

Theory of asymmetric nonadditive binary hard-sphere mixtures.

It is shown that the formal procedure of integrating out the degrees of freedom of the small spheres in a binary hard-sphere mixture works equally well for nonadditive as it does for additive mixtures. For highly asymmetric mixtures (small size ratios) the resulting effective Hamiltonian of the one-component fluid of big spheres, which consists of an infinite number of many-body interactions, should be accurately approximated by truncating after the term describing the effective pair interaction. Using a density functional treatment developed originally for additive hard-sphere mixtures the zero, one, and two-body contribution to the effective Hamiltonian are determined. It is demonstrated that even small degrees of positive or negative nonadditivity have significant effect on the shape of the depletion potential. The second virial coefficient B2, corresponding to the effective pair interaction between two big spheres, is found to be a sensitive measure of the effects of nonadditivity. The variation of B2 with the density of the small spheres shows significantly different behavior for additive, slightly positive and slightly negative nonadditive mixtures. Possible repercussions of these results for the phase behavior of binary hard-sphere mixtures are discussed and it is suggested that measurements of B2 might provide a means of determining the degree of nonadditivity in real colloidal mixtures.

Journal Article↗
PubMed2001

Binary Gaussian core model: fluid-fluid phase separation and interfacial properties.

Using a mean-field equation of state we calculate the density-concentration phase diagrams for a binary mixture of repulsive Gaussian core particles over a range of size ratios. A simple mean-field density functional (DFT) approach, equivalent to the random phase approximation, is used to calculate the surface tension and density profiles of the interface between the demixed fluid phases of the binary mixture. For certain coexisting states oscillations are found in the density profiles on both sides of the interface, i.e., approaching both bulk phases. The form of the oscillations is determined by the asymptotic decay of the bulk total pairwise correlations, and the onset of oscillations in the interfacial density profiles depends on the location of the crossover line (Fisher-Widom line) in the bulk phase diagram where the asymptotic decay changes from monotonic to damped oscillatory. For certain particle size ratios we find another crossover line that separates a region of the phase diagram where the longest-range decay of the pairwise correlations is damped oscillatory from a region where the longest-range decay is damped oscillatory but with a different wavelength. We argue that many of the predictions of the simple DFT approach should remain valid in more refined treatments.

Journal Article↗
PubMed2001

Chronic lymphocytic leukemia incidence is substantially higher than estimated from tumor registry data.

BACKGROUND: Although chronic lymphocytic leukemia (CLL) often is described as the most common leukemia in the U.S. and Western Europe, to the authors' knowledge the true incidence of CLL in the U.S. is unknown. CLL incidence is estimated from tumor registry reports based on tissue pathology and cancer treatment data. Tumor registry data may underestimate the incidence of CLL substantially because CLL can be diagnosed by flow cytometric analysis of peripheral blood cells, and the majority of patients do not require treatment at the time of diagnosis. METHODS: To test the hypothesis that CLL has a higher incidence than estimated from tumor registry data, the authors compared the actual and reported incidence of CLL for a 10-year interval at the Central Arkansas Veterans Healthcare System (CAVHS). The accuracy of surveillance methods for new diagnoses of CLL was confirmed by reviewing the lymphocyte counts in 45,009 CAVHS patients over a 4-year period. RESULTS: The tumor registry correctly reported 58 of 93 patients with CLL (62.4%) who were diagnosed between January 1, 1990 and December 31, 1999. The tumor registry correctly reported 100% of patients with CLL diagnosed between 1990-1991 but reported only 34.5% of patients with CLL diagnosed between 1998-1999. CONCLUSIONS: The incidence of CLL in the CAVHS was 37.6% higher than estimated from tumor registry data due to an increase in the use of peripheral blood immunophenotype as the only diagnostic test for CLL over the time period of the study. These data suggest that the true incidence of CLL may be substantially higher than estimated from tumor registry data.

Humans↗
PubMed2001

Wetting and capillary nematization of a hard-rod fluid: a simulation study.

We present results of a simulation study of a fluid of hard spherocylinders with a length-to-diameter ratio of 15 in contact with a planar hard wall and confined by two parallel hard walls. A Monte Carlo method is developed for simulating fluids in contact with a single wall. Using this method, we find a transition from a uniaxial to a biaxial surface phase, followed, at larger bulk densities, by the formation of a thick nematic film, with the director parallel to the wall, at the wall-isotropic fluid interface. As the density far from the wall cb approaches the value at bulk isotropic-nematic coexistence cI, the thickness of the nematic film appears to increase as -ln(cI-cb). For a fluid confined by two parallel hard walls, a first-order capillary nematization transition is found. The phase equilibria are determined by Gibbs ensemble Monte Carlo simulations for several wall separations. The difference in the coexisting densities of the capillary condensed nematic and isotropic phases becomes smaller upon decreasing the wall separation, and no capillary nematization transition is found when the wall separation is smaller than about twice the length of the spherocylinders. These features imply that the capillary nematization transition ends in a capillary critical point at a critical wall separation. Our simulation results are fully consistent with the findings of our recent theoretical study of the Zwanzig model for a hard-rod fluid.

Journal Article↗
PubMed2001

A randomized clinical trial of exercise and spinal manipulation for patients with chronic neck pain.

STUDY DESIGN: A randomized, parallel-group, single-blinded clinical trial was performed. After a 1-week baseline period, patients were randomized to 11 weeks of therapy, with posttreatment follow-up assessment 3, 6, and 12 months later. OBJECTIVES: To compare the relative efficacy of rehabilitative neck exercise and spinal manipulation for the management of patients with chronic neck pain. SUMMARY OF BACKGROUND DATA: Mechanical neck pain is a common condition associated with substantial morbidity and cost. Relatively little is known about the efficacy of spinal manipulation and exercise for chronic neck pain. Also, the combination of both therapies has yet to be explored. METHODS: Altogether, 191 patients with chronic mechanical neck pain were randomized to receive 20 sessions of spinal manipulation combined with rehabilitative neck exercise (spinal manipulation with exercise), MedX rehabilitative neck exercise, or spinal manipulation alone. The main outcome measures were patient-rated neck pain, neck disability, functional health status (as measured by Short Form-36 [SF-36]), global improvement, satisfaction with care, and medication use. Range of motion, muscle strength, and muscle endurance were assessed by examiners blinded to patients' treatment assignment. RESULTS: Clinical and demographic characteristics were similar among groups at baseline. A total of 93% of the patients completed the intervention phase. The response rate for the 12-month follow-up period was 84%. Except for patient satisfaction, where spinal manipulative therapy and exercise were superior to spinal manipulation with (P = 0.03), the group differences in patient-rated outcomes after 11 weeks of treatment were not statistically significant (P = 0.13). However, the spinal manipulative therapy and exercise group showed greater gains in all measures of strength, endurance, and range of motion than the spinal manipulation group (P < 0.05). The spinal manipulation with exercise group also demonstrated more improvement in flexion endurance and in flexion and rotation strength than the MedX group (P < 0.03). The MedX exercise group had larger gains in extension strength and flexion-extension range of motion than the spinal manipulation group (P < 0.05). During the follow-up year, a greater improvement in patient-rated outcomes were observed for spinal manipulation with exercise and for MedX exercise than for spinal manipulation alone (P = 0.01). Both exercise groups showed very similar levels of improvement in patient-rated outcomes, although the spinal manipulation and exercise group reported greater satisfaction with care (P < 0.01). CONCLUSIONS: For chronic neck pain, the use of strengthening exercise, whether in combination with spinal manipulation or in the form of a high-technology MedX program, appears to be more beneficial to patients with chronic neck pain than the use of spinal manipulation alone. The effect of low-technology exercise or spinal manipulative therapy alone, as compared with no treatment or placebo, and the optimal dose and relative cost effectiveness of these therapies, need to be evaluated in future studies.

Adult↗
PubMed2001

Inhomogeneous model colloid-polymer mixtures: adsorption at a hard wall.

We study the equilibrium properties of inhomogeneous model colloid-polymer mixtures. By integrating out the degrees of freedom of the ideal polymer coils, we derive a formal expression for the effective one-component Hamiltonian of the (hard sphere) colloids that is valid for arbitrary external potentials acting on both the colloids and the polymers. We show how one can recover information about the distribution of polymer in the mixture given knowledge of the colloid correlation functions calculated using the effective one-component Hamiltonian. This result is then used to furnish the connection between the free-volume and perturbation theory approaches to determining the bulk phase equilibria. For the special case of a planar hard wall the effective Hamiltonian takes an explicit form, consisting of zero-, one-, and two-body, but no higher-body, contributions provided the size ratio q=sigma(p)/sigma(c)<0.1547, where sigma(c) and sigma(p) denote the diameters of colloid and polymer respectively. We employ a simple density functional theory to calculate colloid density profiles from this effective Hamiltonian for q=0.1. The resulting profiles are found to agree well with those from Monte Carlo simulations for the same Hamiltonian. Adding very small amounts of polymer gives rise to strong depletion effects at the hard wall which lead to pronounced enhancement of the colloid density profile (close to the wall) over what is found for hard spheres at a hard wall.

Adsorption↗
PubMed2001

830-nm irradiation increases the wound tensile strength in a diabetic murine model.

BACKGROUND AND OBJECTIVE: The purpose of this study was to investigate the effects of low-power laser irradiation on wound healing in genetic diabetes. STUDY DESIGN/MATERIALS AND METHODS: Female C57BL/Ksj/db/db mice received 2 dorsal 1 cm full-thickness incisions and laser irradiation (830 nm, 79 mW/cm(2), 5.0 J/cm(2)/wound). Daily low-level laser therapy (LLLT) occurred over 0-4 days, 3-7 days, or nonirradiated. On sacrifice at 11 or 23 days, wounds were excised, and tensile strengths were measured and standardized. RESULTS: Nontreated diabetic wound tensile strength was 0.77 +/- 0.22 g/mm(2) and 1.51 +/- 0.13 g/mm(2) at 11 and 23 days. After LLLT, over 0-4 days tensile strength was 1.15 +/- 0.14 g/mm(2) and 2.45 +/- 0.29 g/mm(2) (P = 0.0019). Higher tensile strength at 23 days occurred in the 3- to 7-day group (2.72 +/- 0.56 g/mm(2) LLLT vs. 1.51 +/- 0.13 g/mm(2) nontreated; P < or = 0.01). CONCLUSION: Low-power laser irradiation at 830 nm significantly enhances cutaneous wound tensile strength in a murine diabetic model. Further investigation of the mechanism of LLLT in primary wound healing is warranted.

Animals↗
PubMed2001

Cytoplasmic recruitment of INI1 and PML on incoming HIV preintegration complexes: interference with early steps of viral replication.

During the early phase of the retroviral life cycle, only a fraction of internalized virions end up integrating their genome into the chromosome, even though the resulting proviruses are almost systematically expressed. Here, we reveal that incoming retroviral preintegration complexes trigger the exportin-mediated cytoplasmic export of the SWI/SNF component INI1 and of the nuclear body constituent PML. We further show that the HIV genome associates with these proteins before nuclear migration. In the presence of arsenic, PML is sequestered in the nucleus, and the efficiency of HIV-mediated transduction is markedly increased. These results unveil a so far unsuspected cellular response that interferes with the early steps of HIV replication.

Active Transport, Cell Nucleus↗
PubMed2001

Isolation, synthesis, and structure-activity relationships of bioactive benzoquinones from Miconia lepidota from the Suriname rainforest.

Bioactivity-directed fractionation of an EtOAc extract from the leaves of Miconia lepidota afforded the two benzoquinones 2-methoxy-6-heptyl-1,4-benzoquinone (1) and 2-methoxy-6-pentyl-1,4-benzoquinone (primin) (2). This is the first reported isolation of 1. Both quinones 1 and 2 exhibited activity toward mutant yeast strains based on Saccharomyces cerevisiae, indicative of their cytotoxicity and potential anticancer activity. A number of previously synthesized and new analogues were prepared and tested in the same strains. Compounds 1, 2, 2-methoxy-6-butyl-1,4-benzoquinone (5), and 2-methoxy-6-decyl-1,4-benzoquinone (6) were tested in two cytotoxicity assays. In the M109 tumor cell lines, quinones 1, 2, and 6 had an IC(50) value of 10 microg/mL. In the A2780 cell line, compounds 1, 2 and 5 had IC(50) values of 7.9, 2.9, and 3.2 microg/mL, respectively.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Two bioactive saponins from Albizia subdimidiata from the Suriname rainforest.

Bioassay-guided fractionation of a methanol extract of Albizia subdimidiata using the engineered yeast strains 1138, 1140, 1353, and Sc7 of Saccharomyces cerevisiae as the bioassay tool resulted in the isolation of the two active saponins 1 and 2; one of these, albiziatrioside A (1), is described for the first time. The structures of 1 and 2 were established on the basis of HRMS, 1D and 2D NMR spectral data, and GC--MS analysis of the sugar units. Both isolated compounds showed significant cytotoxicity against the A2780 cell line.

Carbohydrate Conformation↗
PubMed2001

The effect of an infusion of esmolol on the incidence of myocardial ischaemia during tracheal extubation following coronary artery surgery.

The aim of this randomised controlled study was to determine whether an esmolol infusion affected the incidence of ST segment changes during weaning from intermittent positive pressure ventilation and tracheal extubation after coronary artery surgery. Thirty-one patients received an infusion of esmolol 0-300 microg x kg(-1) x min(-1) and 37 patients comprised the control group. ST segment changes were monitored using a continuous ambulatory surveillance system. The electrocardiogram, direct arterial pressure and pulse oximetry were monitored continuously. The period of analysis was from 120 min before until 180 min after tracheal extubation. Three patients in the esmolol group developed myocardial ischaemia during the study period compared with 12 in the control group (p = 0.05). Heart rate increased with time during the study period (p = 0.002) in the control group but was unchanged in the esmolol group. Mean heart rate was significantly higher in the control group than in the esmolol group from 40 min before until 180 min after tracheal extubation. Seven patients in the esmolol group suffered adverse events related to the esmolol infusion. Although the use of esmolol reduced the incidence of myocardial ischaemia, the incidence of adverse effects makes it unsuitable prophylaxis for patients after coronary artery surgery.

Adrenergic beta-Antagonists↗
PubMed2001

Success in the toxoplasma dye test.

OBJECTIVES: To compare the success rate of the toxoplasma dye test using different accessory factors (human serum as a source of complement) and different batches of tachyzoites produced in vivo and in vitro. METHODS: Twenty-five accessory factors were used in the dye test to assess both types of tachyzoite. Batches of tachyzoites were produced in vivo (n = 49) and in vitro (n = 23) and their performance assessed against panels of accessory factors. Performance was recorded as success or failure (incorrect results, total killing or no killing). RESULTS: With in vivo tachyzoites 21/25 accessory factors were successful in P > or = 1 dye test runs, whereas with in vitro tachyzoites all 25 were successful. One or more failure was recorded for 19/25 and 12/25 accessory factors using in vivo and in vitro tachyzoites, respectively (P < 0.05). The number of successful dye test runs was less for in vivo (92/141, 65%) than in vitro (140/163, 86%) tachyzoites (P < 0.001). This was due to a higher success rate in citrated accessory factors used for in vitro tachyzoites compared to the corresponding uncitrated accessory factors used for in vivo tachyzoites (P < 0.001). Success in the dye test was recorded for 48/49 and 23/23 batches of in vivo and in vitro tachyzoites, respectively. The number of successful dye test runs was lower with in vivo (156/234, 67%) than in vitro (116/142, 82%) tachyzoites (P < 0.01). CONCLUSIONS: Success in the dye test may be due to the accessory factor, tachyzoites, or a combination of both. Problems due to the accessory factor can be minimized by careful quality control or use of modification procedures. Tachyzoites produced in vitro may also increase success in the dye test. Careful selection of accessory factor/tachyzoite combination makes it possible to use the dye test in a district general hospital.

Animals↗
PubMed2001

Changes in sports injuries to children between 1983 and 1998: comparison of case series.

BACKGROUND: Sports injuries sustained by children are worrying because they prevent and deter participation in physical activity. Before we can address such injuries we need to understand the size of the problem and whether there have been changes in occurrence. A study of sports injuries to children, carried out in a Cardiff Accident and Emergency department in 1983, provided the data against which to compare data gathered in 1998. METHODS: Data on all sports injuries to children aged 16 and under treated between September and December 1998 were compared with those reported for the same hospital, age group, injury and period in 1983. RESULTS: A total of 953 injuries were treated in 1998, representing an increase of 54 per cent [95 per cent confidence interval (CI) 44-64 per cent]. The male:female distribution remained constant and the majority of injuries were due to rugby and soccer. The number of females injured playing rugby and soccer increased and a wider range of sports led to injuries for both males and females. Amongst 10-15-year-olds injury risk increased from 1 in 78 for boys in 1983 to 1 in 22 in 1998 (p < 0.0001). For girls, the increase was from 1 in 117 to 1 in 55 (p < 0.0001). The number of soccer- and rugby-related fractures increased by 52 per cent (95 per cent CI 22-87 per cent). CONCLUSIONS: Sports injury rates have increased considerably over 15 years. With minimal population change, little variation in minor injuries and only small improvements in data capture, the main reason for change appears to be increased participation.

Adolescent↗