Search PubMed⌕ Search

Biomedical subjects

A P Turner

Publications and source records attributed to A P Turner.

At least 19 recordsLinked to original sources
PubMed2006

Influence of caffeine on perception of effort, metabolism and exercise performance following a high-fat meal.

This study examined the effects of caffeine, co-ingested with a high fat meal, on perceptual and metabolic responses during incremental (Experiment 1) and endurance (Experiment 2) exercise performance. Trained participants performed three constant-load cycling tests at approximately 73% of maximal oxygen uptake (VO2max) for 30 min at 20 degrees C (Experiment 1, n = 8) and to the limit of tolerance at 10 degrees C (Experiment 2, n = 10). The 30 min constant-load exercise in Experiment 1 was followed by incremental exercise (15 W . min-1) to fatigue. Four hours before the first test, the participants consumed a 90% carbohydrate meal (control trial); in the remaining two tests, the participants consumed a 90% fat meal with (fat + caffeine trial) and without (fat-only trial) caffeine. Caffeine and placebo were randomly assigned and ingested 1 h before exercise. In both experiments, ratings of perceived leg exertion were significantly lower during the fat + caffeine than fat-only trial (Experiment 1: P < 0.001; Experiment 2: P < 0.01). Ratings of perceived breathlessness were significantly lower in Experiment 1 (P < 0.01) and heart rate higher in Experiment 2 (P < 0.001) on the fat + caffeine than fat-only trial. In the two experiments, oxygen uptake, ventilation, blood [glucose], [lactate] and plasma [glycerol] were significantly higher on the fat + caffeine than fat-only trial. In Experiment 2, plasma [free fatty acids], blood [pyruvate] and the [lactate]:[pyruvate] ratio were significantly higher on the fat + caffeine than fat-only trial. Time to exhaustion during incremental exercise (Experiment 1: control: 4.9, s = 1.8 min; fat-only: 5.0, s = 2.2 min; fat + caffeine: 5.0, s = 2.2 min; P > 0.05) and constant-load exercise (Experiment 2: control: 116 (88 - 145) min; fat-only: 122 (96 - 144) min; fat + caffeine: 127 (107 - 176) min; P > 0.05) was not different between the fat-only and fat + caffeine trials. In conclusion, while a number of metabolic responses were increased during exercise after caffeine ingestion, perception of effort was reduced and this may be attributed to the direct stimulatory effect of caffeine on the central nervous system. However, this caffeine-induced reduction in effort perception did not improve exercise performance.

Adult↗
PubMed2006

Deafened tutors' experiences of delivering the challenging deafness (CD) course: 'recharging my motivational battery'.

The objective was to examine tutors' views regarding motivation to become a lay tutor on a generic, lay-led self-management programme, 'Challenging Deafness' (CD); their experience of course delivery; and the impact of being a tutor on their own lives. Eight tutors (6 male) were interviewed face-to-face. Data were analysed using content analysis. Motivation to become a tutor was associated with desire to help others and establish a new purpose in life. Tutors derived a satisfaction from sharing experiences with course participants and felt their contribution to the welfare of others was valued not only by course participants, but also by friends, family and society. Delivering CD courses reinforced tutors' own self-management, helped develop new skills (e.g. giving presentations), and enhanced confidence. Challenges associated with the tutor role included fatigue, travelling to venues, and managing some course participants. Although tutors felt supported in their role, some felt that advertising materials should reflect the psychosocial nature of the course. Several tutors suggested course modifications specific to the needs of deafened adults.

Adaptation, Psychological↗
PubMed2005

Prevalence and correlates of depression among veterans with multiple sclerosis.

OBJECTIVES: To establish the prevalence of major depressive episode (MDE) in a large sample of veterans with multiple sclerosis (MS); to identify demographic characteristics, aspects of disease presentation, and perceptions of disability associated with greater concurrent risk for MDE; and to examine the relationship between MDE, service utilization, and activity participation. METHODS: Veterans with MS (n = 1,032) were identified via computer database and surveyed by mail; 451 (43.7%) responded. RESULTS: Twenty-two percent of the sample met criteria for current MDE. Low income, unemployment, presence of falls, younger age, absence of a marital partner, and high levels of perceived disability due to bowel functioning were independently associated with MDE. Disease subtype, disease duration, use of disease modifying therapies, and perceived disability due to mobility or bladder problems were unrelated to MDE. Current MDE was in turn associated with increased primary care visits and increased impact of disease upon activity participation. Similar correlates were associated with minor depressive episode. CONCLUSIONS: Unlike the general population, rates of depression in this predominantly male sample were similar to those found in predominantly female samples of persons with multiple sclerosis. Specific aspects of disability were differentially associated with depression, and depression was independently associated with increased service utilization and increased participation limitations.

Data Collection↗
PubMed2005

A 12-month follow-up study of self-management training for people with chronic disease: are changes maintained over time?

OBJECTIVE: A previous study reported some improved outcomes at 4-month follow-up after attendance on a lay-led, chronic disease self-management course (CDSMC). The purpose of this study was to determine whether changes were maintained over time (i.e. at 12 months) and to describe participants' current use of self-management techniques. DESIGN: The study was a 12-month follow-up of a sample of 171 participants who attended a CDSMC in the UK. METHOD: Data were collected by self-administered questionnaires mailed to participants 12 months after they commenced a CDSMC and via telephone interviews with a sub-sample. RESULTS: The sample had a mean age of 54 years, mean disease duration of 16 years, 73% were women, and chronic diseases included endometriosis, depression, diabetes, myalgic encephalomyelitis, osteoporosis and polio. The significant improvements in outcomes identified at 4 months (i.e. cognitive symptom management, self-efficacy, communication with physician, fatigue, anxious and depressed moods and health distress) were sustained at 12 months. No significant changes between 4- and 12-month assessments were found on any study variables. Interview data confirmed that participants continued to use some of the self-management techniques learned on the course. CONCLUSION: Attendance on the CDSMC may lead to longer-term changes in key outcomes such as self-efficacy, use of some self-management behaviours and some aspects of health status (e.g. fatigue, depressed mood).

Activities of Daily Living↗
PubMed2004

Absence of long-term modulation of ventilation by dead-space loading during moderate exercise in humans.

The stability of arterial PCO(2) (P(a)CO(2)) during moderate exercise in humans suggests a CO(2)-linked control that matches ventilation (V(E)) to pulmonary CO(2) clearance (VCO(2)). An alternative view is that V(E) is subject to long-term modulation (LTM) induced by "hyperpnoeic history". LTM has been reported with associative conditioning via dead-space (V(D)) loading in exercising goats (Martin and Mitchell 1993). Whether this prevails in humans is less clear, which may reflect differences in study design (e.g. subject familiarisation; V(D) load; whether or not V(E) is expressed relative to VCO(2); choice of P(a)CO(2) estimator). After familiarisation, nine healthy males performed moderate constant-load cycle-ergometry (20 W-80 W-20 W; <lactate threshold, theta;(L)): day 1, pre-conditioning, n=3; day 2, conditioning (V(D)=1.59 l, doubling V(E) at 20 W and 80 W), n=8 with 10 min rest between tests; and, after 1 h rest, post-conditioning, n=3. Gas exchange was determined breath-by-breath. Post-conditioning, neither the transient [phase 1, phase 2 (capital EF, Cyrillic1, capital EF, Cyrillic2)] nor steady-state V(E) exercise responses, nor their proportionality to VCO(2), differed from pre-conditioning. For post-conditioning trial 1, steady-state V(E) was 28.1 (4.7) l min(-1) versus 29.1 (3.8) l min(-1) pre-conditioning, and mean-alveolar PCO(2) (a validated P(a)CO(2) estimator) was 5.53 (0.48) kPa [41.5 (3.6) mmHg] versus 5.59 (0.49) kPa [41.9 (3.7) mmHg]; the capital EF, Cyrillic1 V(E) increment was 4.2 (2.9) l min(-1) versus 5.2 (1.9) l min(-1); the capital EF, Cyrillic2 V(E) time-constant (tau) was 64.4 (24.1) s versus 64.1 (25.3) s; tauV(E)/tauVCO(2) was 1.12 (0.04) versus 1.10 (0.04); and the V(E)-VCO(2) slope was 21.7 (3.4) versus 21.2 (3.2). In conclusion, we could find no evidence to support ventilatory control during moderate exercise being influenced by hyperpnoeic history associated with dead-space loading in humans.

Adaptation, Physiological↗
PubMed2004

Volunteer, lay tutors' experiences of the Chronic Disease Self-Management Course: being valued and adding value.

Chronic disease is a public health issue that could be addressed, in part, by increasing the ability of individuals to better manage their condition and its consequences on a day-to-day basis. One intervention designed to facilitate this is the Chronic Disease Self Management Course (CDSMC) that is delivered by volunteer, lay tutors who themselves have a chronic disease. Although there is growing evidence of course effectiveness for participants, the experiences of tutors have been neglected. This study aims to address this omission. Telephone interviews were conducted with 11 (six male) tutors: all interviews were transcribed and thematically analysed. Being a volunteer lay-tutor was perceived to be an enjoyable and valuable experience despite the challenges associated with course delivery, such as organizational demands and managing the diverse needs of mixed groups of chronic disease participants that led to a tension between disease-specific needs and the generic approach of the course. Being valued and adding value to the lives of others were key benefits of being a volunteer tutor, along with increased confidence that they were doing something positive for others. Course delivery prompted the initiation and maintenance of tutors' own self-management behaviours.

Adult↗
PubMed2004

Comparative responses of molluscs and fish to environmental estrogens and an estrogenic effluent.

It is now well established that there is a diverse array of chemical discharged into the environment that can mimic or antagonise the action of hormones. These endocrine-disrupting chemicals (EDCs) can thus interact with physiological systems and cause alterations in development, growth and reproduction in wildlife that are exposed to them. As yet, however, there is little information on the relative sensitivities of different wild life groups to these chemicals and/or mixtures of them (e.g. estrogenic effluents) and hence, there are fundamental shortfalls in our knowledge of the ecological chemicals (17alpha-ethinylestradiol; EE2, bisphenol-A, and 4-tert octylphenol) and a mixture containing these chemicals (treated sewage effluent) on embryo production in the prosobranch mollusc, Potamopyrgus antipodarum, were studied and compared with the effects of EE2 and the same estrogenic effluent on vitellogenin induction and/or egg production in various species of freshwater fish (fathead minnow; Pimaphales promelas, rainbow trout (Oncorhynchus mykiss); Cyprinus carpio, carp; Cyprinus carpio). The lab-based studies demonstrated that all of the tested chemicals (known to be estrogenic and to cause reproductive effects in fish) also affected embryo production in P. antipodarum. Furthermore, exposure to EE2 induced similar reproductive responses in the snails as in the fathead minnow (Pimephales promelas), stimulating egg/embryo production at low doses (up to 1 ng/l in the minnow and 25 ng/l in the snail) and causing inhibitory effects at higher doses. A similar pattern of embryo production occurred in P. antipodarum when it was exposed to a graded concentration of treated sewage effluent containing mixtures of estrogenic EDCs and hence, the total number of new embryos produced by the snails increased steadily over the 9 week exposure period in treated snails. Plasma vitellogenin concentrations in two species of male fish (the rainbow trout and the carp) also increased over the same time period. These data indicate that both the nature of the response and the relative sensitivities to environmental estrogens in P. antipodarum and three different fish species fish are comparable. P. andtipodarum is thus, potentially a sensitive test organism for assessing estrogenicity of chemicals with a relevance to their activity in vertebrates.

Analysis of Variance↗
PubMed2003

Comparative responses of molluscs and fish to environmental estrogens and an estrogenic effluent.

It is now well established that there is a diverse array of chemicals discharged into the environment that can mimic or antagonise the action of hormones. These endocrine-disrupting chemicals (EDCs) can thus interact with physiological systems and cause alterations in development, growth and reproduction in wildlife that are exposed to them. As yet, however, there is little information on the relative sensitivities of different wildlife groups to these chemicals and/or mixtures of them (e.g. estrogenic effluents) and hence, there are fundamental shortfalls in our knowledge of the ecological importance of endocrine disruption in wildlife. In this study, the effects of exposure to individual estrogenic chemicals (17alpha-ethinylestradiol; EE2, bisphenol-A, and 4-tert octylphenol) and a mixture containing these chemicals (treated sewage effluent) on embryo production in the prosobranch mollusc, Potamopyrgus antipodarum, were studied and compared with the effects of EE2 and the same estrogenic effluent on vitellogenin induction and/or egg production in various species of freshwater fish (fathead minnow; Pimaphales promelas, rainbow trout (Oncorhynchus mykiss); Cyprinus carpio, carp; Cyprinus carpio). The lab-based studies demonstrated that all of the tested chemicals (known to be estrogenic and to cause reproductive effects in fish) also affected embryo production in P. antipodarum. Furthermore, exposure to EE2 induced similar reproductive responses in the snails as in the fathead minnow (Pimephales promelas), stimulating egg/embryo production at low doses (up to 1 ng/l in the minnow and 25 ng/l in the snail) and causing inhibitory effects at higher doses. A similar pattern of embryo production occurred in P. antipodarum when it was exposed to a graded concentration of treated sewage effluent containing mixtures of estrogenic EDCs and hence, the total number of new embryos produced by the snails increased steadily over the 9 weeks exposure period in treated snails. Plasma vitellogenin concentrations in two species of male fish (the rainbow trout and the carp) also increased over the same time period. These data indicate that both the nature of the response and the relative sensitivities to environmental estrogens in P. antipodarum and three different fish species fish are comparable. P. antipodarum is thus, potentially a sensitive test organism for assessing estrogenicity of chemicals with a relevance to their activity in vertebrates.

Animals↗
PubMed2003

Self-management training for people with chronic disease: an exploratory study.

OBJECTIVE: To determine the effectiveness of a community-based Chronic Disease Self-management Course (CDC) for UK participants with a range of chronic diseases. DESIGN: The study was a multiple baseline, pre-test post test design with a sample of 185 participants who attended a CDC delivered in community settings by lay tutors, in the UK. METHOD: Data were collected by self-completed questionnaires before attendance and at four-month follow-up. RESULTS: The sample comprised 72% women (mean age = 53 years, mean disease duration = 16 years). The main chronic diseases included endometriosis, depression, diabetes, myalgic encephalomyelitis, osteoporosis and polio. Adjusting for baseline values and gender, small to moderate increases were found on cognitive symptom management, self-efficacy (disease and symptoms) and communication with physician. A similar sized decrease was found on fatigue, and small decreases were evident on anxious and depressed moods, and health distress. There were no changes in the use of health care resources, or on self-reported exercise behaviour. CONCLUSION: The results of this exploratory study suggest that self-management training for people with chronic diseases can offer benefits in terms of enhanced self-efficacy, greater use of cognitive behavioural techniques, and improvement in some aspects of physical and psychological well-being.

Analysis of Variance↗
PubMed2001

Surface-grafted molecularly imprinted polymers for protein recognition.

A technique for coating microplate wells with molecularly imprinted polymers (MIPs) specific for proteins is presented. 3-Aminophenylboronic acid was polymerized in the presence of the following templates: microperoxidase, horseradish peroxidase, lactoperoxidase, and hemoglobin, via oxidation of the monomer by ammonium persulfate. This process resulted in the grafting of a thin polymer layer to the polystyrene surface of the microplates. Imprinting resulted in an increased affinity of the polymer toward the corresponding templates. The influence of the washing procedure, template concentration, and buffer pH on the polymer affinity was analyzed. It was shown that the stabilizing function of the support and spatial orientation of the polymer chains and template functional groups are the major factors affecting the imprint formation and template recognition. Easy preparation of the MIPs, their high stability, and their ability to recognize small and large proteins, as well as to discriminate molecules with small variations in charge, make this approach attractive and broadly applicable in biotechnology, assays and sensors.

Animals↗
PubMed2001

Molecular imprinting: at the edge of the third millennium.

Molecularly imprinted polymers (MIPs) represent a new class of materials that have artificially created receptor structures (1-3). Since their discovery in 1972, MIPs have attracted considerable interest from scientists and engineers involved with the development of chromatographic adsorbents, membranes, sensors and enzyme and receptor mimics.

Biotechnology↗
PubMed2001

"Bite-and-Switch" approach using computationally designed molecularly imprinted polymers for sensing of creatinine.

A method for the selective detection of creatinine is reported, which is based on the reaction between polymerised hemithioacetal, formed by allyl mercaptan, o-phthalic aldehyde, and primary amine leading to the formation of fluorescent isoindole complex. This method has been demonstrated previously for the detection of creatine using creatine-imprinted molecularly imprinted polymers (MIPs) Since MIPs created using traditional methods were unable to differentiate between creatine and creatinine, a new approach to the rational design of a molecularly imprinted polymer (MIP) selective for creatinine was developed using computer simulation. A virtual library of functional monomers was assigned and screened against the target molecule, creatinine, using molecular modelling software. The monomers giving the highest binding score were further tested using simulated annealing in order to mimic the complexation of the functional monomers with template in the monomer mixture. The result of this simulation gave an optimised MIP composition. The computationally designed polymer demonstrated superior selectivity in comparison to the polymer prepared using traditional approach, a detection limit of 25 microM and good stability. The "Bite-and-Switch" approach combined with molecular imprinting can be used for the design of assays and sensors, selective for amino containing substances.

Biosensing Techniques↗
PubMed2001

Substitution of antibodies and receptors with molecularly imprinted polymers in enzyme-linked and fluorescent assays.

A new technique for coating microtitre plates with molecularly imprinted polymers (MIP), specific for low-molecular weight analytes (epinephrine, atrazine) and proteins is presented. Oxidative polymerization was performed in the presence of template; monomers: 3-aminophenylboronic acid (APBA), 3-thiopheneboronic acid (TBA) and aniline were polymerized in water and the polymers were grafted onto the polystyrene surface of the microplates. It was found that this process results in the creation of synthetic materials with antibody-like binding properties. It was shown that the MIP-coated microplates are particularly useful for assay development. The high stability of the polymers and good reproducibility of the measurements make MIP coating an attractive alternative to conventional antibodies or receptors used in enzyme linked immunosorbent assay (ELISA).

Antibodies↗
PubMed2001

Multivariate evaluation of factors influencing the performance of a formic acid biosensor for use in air monitoring.

A formic acid biosensor for air monitoring has been evaluated using chemometric methods. Using experimental design eleven factors that could influence the performance of the biosensor were examined. The response matrices consisted of six parameters (steady state currents at three different formic acid concentrations and response rates during changes in formic acid concentrations) describing the performance of the biosensor. The data were evaluated using a combination of principal component analysis (PCA) and multiple linear regression (MLR). To confirm the conclusions from the PCA-MLR partial least squares (PLS) was also used. The most important factor for the biosensor performance was found to be the enzyme concentration. Using the information from the chemometric analyses the optimum operation conditions for the biosensor were determined. The steady state currents were increased by 18-30% and the initial two response rates increased by 47-89% compared with a biosensor that had not been optimised.

Air Pollutants, Occupational↗
PubMed2001

Evaluating a brief alcohol intervention with fraternities.

OBJECTIVE: The current study tested the efficacy of a brief intervention designed to reduce drinking and drinking-related consequences among first-year fraternity members. METHOD: Twelve fraternities were randomly assigned to receive either a motivational enhancement intervention with individual and housewide feedback components (n = 6 houses) or a treatment-as-usual control condition (n = 6 houses). Individual feedback was delivered either by peer interviewers or professional research staff. Participants were assessed during their pledge (first) year of house membership and during a follow-up period 1 year later. RESULTS: Of the participants who completed follow-up (N = 120), fraternity members who received the brief intervention reported significant reductions in alcohol use (total average consumption) and typical peak blood alcohol concentrations when compared with fraternity members in the control condition. No differences in drinking-related consequences were observed. Fraternity members who received their individualized feedback from peer interviewers and professional members of the research staff reported similar outcomes. CONCLUSIONS: Results provide support for the efficacy of a brief motivational enhancement intervention in reducing drinking within this high-risk population. The cost-effective use of peer interviewers appears to be a promising strategy for delivering individualized prevention programming in college populations.

Adolescent↗
PubMed2000

Capillary electrophoresis coupled to biosensor detection.

The present review highlights some modern aspects of biosensor revelation, a detection method which has already found a large number of applications in healthcare, food industry and environmental analysis. First, the concept of bio-recognition, which is at the heart of biosensor technology, is discussed, with emphasis on host-guest-like recognition mechanisms. This detection device has been successfully coupled, in its first applications, to chromatographic columns, which allow a high resolution of complex mixtures of analytes prior to interaction with the biosensing unit. The properties of the transducing elements, which should generate a signal (e.g., electrochemical, thermal, acoustic, optical) of proper intensity and of relative fast rise, are additionally evaluated and discussed. The review then focuses on potential applications of biosensing units in capillary electrophoresis (CE) devices. CE appears to be an excellent separation methodology to be coupled to biosensor detection, since it is based on miniaturized electrophoretic chambers, fast analysis times, complete automation in sample handling and data treatment and requires extremely small sample volumes. Although only a few applications of CE-based biosensors have been described up to the present, it is anticipated that this hyphenated technique could have a considerable expansion in the coming years.

Biosensing Techniques↗
PubMed2000

An assay for ascorbic acid based on polyaniline-coated microplates.

A technique for modification of the microtiter reader plates well with a polyaniline (PANI) film sensitive for ascorbic acid is presented. The principle of the analyte detection is based on monitoring the changes in optical absorption of the PANI film resulting from the reduction process initiated by ascorbic acid. The detection limit for ascorbic acid is 1 mg/L. Testing with real samples (soft drinks, fruit juices) gave good correlation of the method with iodimetric titration. High sensitivity, stability, and good reproducibility of the measurements make the proposed system an attractive alternative to traditional assays, used in medicine, ecology, and biotechnology.

Aniline Compounds↗