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Biomedical subjects

R Turner

Publications and source records attributed to R Turner.

At least 181 records · Page 10Linked to original sources
PubMed1994

Cost utility of maintenance treatment of recurrent depression with sertraline versus episodic treatment with dothiepin.

The objective of this study was to model, for patients at risk of recurrent depression, the cost-utility of maintenance therapy with sertraline compared with treatment of acute episodes with dothiepin ('episodic treatment'). Using clinical decision analysis techniques, a Markov state-transition model was constructed to estimate the lifetime costs and quality-adjusted life-years (QALYs) of the 2 therapeutic strategies. The model follows 2 cohorts of 35-year-old women at high risk for recurrent depression over their lifetimes. Model construction and relevant data (probabilities) for performing the analysis were based on existing clinical knowledge. Two physician panels were used to obtain estimates of recurrence probabilities not available in the literature, health utilities, and resource consumption. Costs were obtained from published sources. The baseline analysis showed that it costs 2172 British pounds sterling ($US3692, 1991 currency) to save an additional QALY with sertraline maintenance treatment. Sensitivity analysis showed that the incremental cost-utility ratio ranged from 557 British pounds sterling to 5260 British pounds sterling per QALY. Overall, the resulting ratios are considered to be well within the range of cost-utility ratios that support the adoption and appropriate utilisation of a technology. Based on the study assumptions, long term maintenance treatment with sertraline appears to be clinically and economically justified choice for patients at high risk of recurrent depression.

1-Naphthylamine↗
PubMed1994

Audit of the use of doctors' holding power under Section 5(2) of the Mental Health Act 1983.

The legal documentation and hospital case-notes of all patients detained during 1989 in Nottingham and Lincoln under Section 5(2) of the Mental Health Act 1983 (empowering the emergency detention of a voluntary inpatient who wishes to leave), were audited to establish if there were any predictors of conversion to longer-term restraint under that Act. Of the 146 Section 5(2) orders, 80 were converted to a Section 2 or 3; the conversion rate in people detained outside normal working hours and those detained within 12 hours of admission was significantly lower; and the conversion rate was significantly higher in people with a mental illness, compared with those with personality disorders, substance abuse and stress reactions. No differences existed in the overall conversion rates of people managed by senior or junior doctors, but junior doctors who did not seek the advice of a senior doctor had a significantly lower rate of conversion than those who did. These results indicate that Section 5(2) may have been inappropriately used in up to 45% of cases, and underline the need for appropriate consultation.

Commitment of Persons with Psychiatric Disorders↗
PubMed1994

Quality of life: experience with sertraline.

The socioeconomic impact of major depression is considerable, due to poor patient functioning and increased social impairment, bed disability days, and use of health care resources. Major depression and the side effects of antidepressants medication also adversely affect patients' quality of life (QOL). However, few clinical trials of major depression examine QOL as a measure of treatment outcome. A comprehensive, quantitative QOL instrument for depression was recently tested and validated as conforming to accepted psychometric standards. The sertraline quality of life battery (SQOLB) consists of nine domains measuring health perceptions: energy/vitality, cognitive function, social interaction, alertness behavior, work behavior, home management, life satisfaction, and bed disability days. The SQOLB has been used in two open-label trials of sertraline. In the first study, the SQOLB was administered to 400 patients with major depression at baseline and final visit in a 6 week, open-label, general practice study. At endpoint, mean Montgomery-Asberg Depression Rating Scale (MADRS) and Clinical Global Impression (CGI) scores were significantly improved. The QOL battery also showed significant (p < 0.001) positive changes from baseline to final visit in all nine domains measured. In the second study, the SQOLB was used as part of an 8 week, open-label trial of sertraline in 308 UK hospital outpatients being treated for depression by psychiatrists. Sertraline was effective in managing the depression and caused statistically significant improvements (p < 0.001) in all QOL domains measured. The QOL scales give a better indication of the effect of pervasive depressive symptoms on a patient's life than rating scales of depressive symptomatology.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Naphthylamine↗
PubMed1994

Diabetes screening.

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Diabetes Mellitus, Type 2↗
PubMed1993

Activation of human primary visual cortex during visual recall: a magnetic resonance imaging study.

The degree to which the process involved in visual perception and visual imagery share a common neuroanatomical substrate is unclear. Physiological evidence for localization of visual imagery early in the visual pathways would have important bearing on current theories of visual processing. A magnetic resonance imaging technique sensitive to regional changes in blood oxygenation was used to obtain functional activation maps in the human visual cortex. During recall of a visual stimulus, focal increases in signal related to changes in blood flow were detected in V1 and V2 cortex in five of seven subjects. These experiments show that the same areas of the early visual cortex that are excited by visual stimulation are also activated during mental representation of the same stimulus. Some of the processes used in topographically mapped cortical areas during visual perception may also be utilized during visual recall.

Adult↗
PubMed1993

Paradoxical pain.

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Drug Interactions↗
PubMed1993

Cytochrome bo from Escherichia coli: identification of haem ligands and reaction of the reduced enzyme with carbon monoxide.

Inner membranes were prepared from Escherichia coli strain RG 145, which is deficient in cytochrome bd, but overexpresses cytochrome bo [Au and Gennis (1987) J. Bacteriol. 169, 3237-3242]. The latter was purified 7-fold by extracting the membranes with octyl beta-D-glucopyranoside, followed by chromatography on DEAE-Sepharose, yielding 150 mg of protein/150 g wet weight of cells. Optical e.p.r. and low-temperature m.c.d. (magnetic circular dichroism) spectroscopies were used to investigate the nature of the protein ligands to the two haems in cytochrome bo from E. coli. Low-spin ferric haem b, the origin of a rhombic e.p.r. spectrum with g = 2.98, 2.26 and 1.50, gives rise to a charge-transfer band in the near-i.r. m.c.d. spectrum at 1622 nm. It is therefore concluded that haem b is co-ordinated by two histidine residues. The low-temperature m.c.d. spectrum of dithionite-reduced cytochrome bo comprises bands due both to low-spin ferrous haem b and to high-spin ferrous haem o. The bands arising from haem o show a direct correspondence with those in the m.c.d. spectrum of five-co-ordinate histidine-ligated ferrous haems such as myoglobin, implying that the protein residue liganding haem o is also histidine. This assignment was confirmed by measuring the e.p.r. spectrum of the nitric oxide derivative of fully reduced cytochrome bo. This showed a rhombic spectrum with g = 2.098, 2.008 and 1.987, and nuclear hyperfine splitting consistent with the co-ordination of ferrous haem by NO and histidine. The hyperfine splittings observed were 1.95 +/- 0.05 mT for the 14N of the NO ligand and 0.75 +/- 0.05 mT for the 14N of the proximal histidine. The e.p.r. spectrum of some samples of oxidized cytochrome bo show, at temperatures below 15 K, broad signals at g = 7.6, 3.6 and 2.8, and other preparations in the presence of glycerol yield signals at g = 10.8, 3.2 and 2.6. These signals, which are abolished by the addition of cyanide, are assigned to the binuclear centre, cytochrome o-CuB, suggesting that the binuclear site may display heterogeneity. Carbon monoxide reacts with the reduced enzyme with a stoichiometry of 1:1, and the dissociation constant for this reaction was determined to be 1.7 x 10(-6)M. The second-order rate constants for this reaction were measured and shown to be similar to those determined for bovine cytochrome aa3 [Gibson and Greenwood (1963) Biochem. J. 86, 541-554].

Carbon Monoxide↗
PubMed1993

Functional mapping of the human visual cortex at 4 and 1.5 tesla using deoxygenation contrast EPI.

The effects of photic stimulation on the visual cortex of human brain were studied by means of gradient-echo echo-planar imaging (EPI). Whole-body 4 and 1.5 T MRI systems, equipped with a small z axis head gradient coil, were used. Variations of image intensity of up to 28% at 4 T, and up to 7% at 1.5 T, were observed in primary visual cortex, corresponding to an increase of blood oxygenation in regions of increased neural activity. The larger effects at 4 T are due to the increased importance of the susceptibility difference between deoxygenated and oxygenated blood at high fields.

Adult↗
PubMed1993

The protein kinase C, calcium-independent and calcium-dependent kinase activities of glial cells in primary culture and subculture.

The activity of calcium-independent, calcium-dependent and calcium + phospholipid-dependent (protein kinase C) kinases in cytosol fractions from rat brain glial cells in primary culture and from subcultured astrocytes and in oligodendrocyte-type 2 astrocyte lineage glia has been measured with histone Type IIIS as substrate. Accurate measurement of protein kinase C activity was achieved only after chromatography of glial cytosols on DE-52 anion exchange columns to remove an endogenous inhibitor, identified tentatively as a phosphatase possibly of the protein phosphatase 2A class. The specific activity of protein kinase C in glial cell cytosol increased from 7.5 +/- 0.8 to 37.9 +/- 0.9 nmol32P incorporated/mg protein/10 min with increasing culture age. Protein kinase C activity in glial cytosol was significantly higher when primary cultures were grown in a defined medium lacking serum. Astrocyte-conditioned medium and phorbol esters caused a rapid translocation of glial cell protein kinase C activity from cytosol to membrane compartments. Myelin basic protein and protamine have been compared with histone as substrates for measurement of calcium-independent, calcium-dependent and calcium + phospholipid-dependent kinase activities in glial cytosol.

Animals↗
PubMed1993

Gradient coil design: a review of methods.

Methods of coil design for MRI gradient coils and other purposes are discussed. The conflicting requirements for satisfactory gradient coil performance are described and analyzed. Design methods are classified into discrete wire techniques and current density techniques. The advantages and disadvantages of each group of methods are described, and optimization methods are summarized. These include the target field approach, and constrained inductance and power minimization. Design for low fringe fields is described, including active shielding.

Equipment Design↗
PubMed1993

Is water diffusion restricted in human brain white matter? An echo-planar NMR imaging study.

Water diffusion is extremely anisotropic in brain white matter, depending on myelin fiber orientation. A suggested, but unproven cause of anisotropy is that, in the direction transverse to the myelin fibers, axonal water diffusion is prevented by the presence of the myelin sheath. We found, however, using an ultra-fast nuclear magnetic resonance imaging technique, that the dependence of the diffusion coefficient on the diffusion time does not support the model of water restriction by impenetrable barriers. These results, which were obtained non-invasively in vivo in the human brain, imply that water diffuses with a measurable rate across myelin fibers.

Body Water↗
PubMed1993

Hip sepsis from retroperitoneal rupture of diverticular disease.

Retroperitoneal perforation of diverticular disease is very uncommon and can be difficult to diagnose because of possible pathways of communication between the retroperitoneal space and the thigh. An iliopsoas abscess from a ruptured diverticulum may drain into the hip joint if the capsule has been violated. Cases of abscesses or gas in the thigh have been reported in which thigh pain was the predominant symptom, overshadowing any abdominal signs. We report a case in which hip sepsis due to a ruptured diverticulum was the presenting feature.

Aged↗
PubMed1993

Diffusion and perfusion magnetic resonance imaging in brain tumors.

The article reviews recent progress made in the field of diffusion and perfusion magnetic resonance (MR) imaging and presents possible applications in brain tumors. Diffusion, a new parameter, provides useful data to assess tissue structure and function. Perfusion MR imaging gives results that are somewhat similar to those obtained with classic non-MR imaging methods, but it offers several potential advantages.

Brain Neoplasms↗
PubMed1992

Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation.

Neuronal activity causes local changes in cerebral blood flow, blood volume, and blood oxygenation. Magnetic resonance imaging (MRI) techniques sensitive to changes in cerebral blood flow and blood oxygenation were developed by high-speed echo planar imaging. These techniques were used to obtain completely noninvasive tomographic maps of human brain activity, by using visual and motor stimulus paradigms. Changes in blood oxygenation were detected by using a gradient echo (GE) imaging sequence sensitive to the paramagnetic state of deoxygenated hemoglobin. Blood flow changes were evaluated by a spin-echo inversion recovery (IR), tissue relaxation parameter T1-sensitive pulse sequence. A series of images were acquired continuously with the same imaging pulse sequence (either GE or IR) during task activation. Cine display of subtraction images (activated minus baseline) directly demonstrates activity-induced changes in brain MR signal observed at a temporal resolution of seconds. During 8-Hz patterned-flash photic stimulation, a significant increase in signal intensity (paired t test; P less than 0.001) of 1.8% +/- 0.8% (GE) and 1.8% +/- 0.9% (IR) was observed in the primary visual cortex (V1) of seven normal volunteers. The mean rise-time constant of the signal change was 4.4 +/- 2.2 s for the GE images and 8.9 +/- 2.8 s for the IR images. The stimulation frequency dependence of visual activation agrees with previous positron emission tomography observations, with the largest MR signal response occurring at 8 Hz. Similar signal changes were observed within the human primary motor cortex (M1) during a hand squeezing task and in animal models of increased blood flow by hypercapnia. By using intrinsic blood-tissue contrast, functional MRI opens a spatial-temporal window onto individual brain physiology.

Animals↗
PubMed1992

A quantitative model for the mechanism of action of the cytochrome c peroxidase of Pseudomonas aeruginosa.

Each of the elementary reaction steps in both the activation process and catalytic cycle of the cytochrome c peroxidase of Pseudomonas aeruginosa was characterized using stopped-flow methods. A synthesis of these data led to the establishment of a quantitative model for the action of this enzyme. Comparisons were made between experimental data and calculations over a wide range of enzyme, reductant and H2O2 concentrations. Close agreement was found between empirical and simulated reaction time courses from millisecond to tens of seconds time ranges, giving us confidence in the validity of the quantitative model of this enzyme's actions.

Azurin↗