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Biomedical subjects

A Stevens

Publications and source records attributed to A Stevens.

At least 73 records · Page 4Linked to original sources
PubMed2000

Health technology diffusion rates. Statins, coronary stents, and MRI in England.

OBJECTIVE: To analyze the rates and influences on the adoption of three selected health technologies: statins, coronary stents, and magnetic resonance imaging (MRI). METHODS: A retrospective diffusion study using primary care prescribing data and questionnaire responses from acute hospital trusts in the West Midlands region (population 5.3 million or 10% of England). RESULTS: The selected technologies had markedly different diffusion curves. Statins diffused rapidly soon after launch. Coronary stents were initially used 6 years after first availability, but within 2 years all responding hospitals reported using them. MRI scanners were initially purchased 6 years after first availability with a subsequently slow rate of diffusion, and are still absent from some hospitals. Influences on the adoption of each technology were different. Commercial marketing was reported as a major influence on the diffusion of statins but not at all on MRIs. Cost impact was a major negative influence on the diffusion of MRI scanners and statins, whereas enthusiastic individuals were key to the diffusion of stents. CONCLUSIONS: Influences on adoption and consequent diffusion rates are very different for different health technologies. It is not at all clear that such diffusion patterns relate well to an optimum timing rate. This has important implications for technology gatekeepers in health care.

Anticholesteremic Agents↗
PubMed2000

Comparison of once- and twice-daily dosing of fluticasone propionate 200 micrograms per day administered by diskus device in patients with asthma treated with or without inhaled corticosteroids.

BACKGROUND: There are limited published data regarding the efficacy of once- versus twice-daily administration of flutica-sone propionate. OBJECTIVE: Our purpose was to evaluate the effectiveness of fluticasone propionate powder 200 microg/d administered as a once- or twice-daily dosage regimen in patients who were currently being treated with bronchodilators only (BD patients) and in patients who required inhaled corticosteroids for maintenance treatment of asthma (ICS patients). METHODS: Five hundred seventy patients were randomly assigned to receive one of the following inhaled treatments through the Diskus device (Glaxo Wellcome, Research Triangle Park, NC) for 12 weeks: fluticasone propionate 100 microg twice daily (FP100BID) or 200 microg once daily (FP200QD) or placebo. RESULTS: BD patients treated with FP100BID, FP200QD, and placebo had mean increases in FEV(1) from baseline to end point of 0. 49 L, 0.37 L, and 0.21 L, respectively (P <.001, FP100BID vs placebo; P =.05, FP200QD vs placebo). ICS patients treated with FP100BID and FP200QD had mean increases in FEV(1) of 0.27 L and 0.11 L, respectively, compared with a decrease in FEV(1) of -0.08 L with placebo (P <.001, FP100BID vs placebo; P =.023, FP200QD vs placebo). BD patients treated with FP100BID and FP200QD had mean increases in morning peak expiratory flow from baseline to end point of 31 L/min and 27 L/min, respectively, compared with a 1 L/min increase in patients treated with placebo. ICS patients treated with FP100BID had a mean increase in morning peak expiratory flow (from baseline to end point) of 18 L/min compared with mean decreases of -3 L/min and -12 L/min in the FP200QD and placebo groups, respectively. More patients were withdrawn from placebo (26% and 48%, in BD and ICS patients, respectively) than from fluticasone propionate (7%-9% [BID-QD] and 18%-32% [BID-QD], in BD and ICS patients, respectively) because of failure to meet predetermined asthma stability criteria. CONCLUSION: The efficacies of FP100BID and FP200QD were comparable with regard to improvement in pulmonary function and asthma stability in BD patients. In ICS patients, asthma control was maintained with FP200QD, whereas FP100BID provided greater improvements in pulmonary function and asthma stability.

Administration, Inhalation↗
PubMed2000

Saccharomyces cerevisiae RAI1 (YGL246c) is homologous to human DOM3Z and encodes a protein that binds the nuclear exoribonuclease Rat1p.

The RAT1 gene of Saccharomyces cerevisiae encodes a 5'-->3' exoribonuclease which plays an essential role in yeast RNA degradation and/or processing in the nucleus. We have cloned a previously uncharacterized gene (YGL246c) that we refer to as RAI1 (Rat1p interacting protein 1). RAI1 is homologous to Caenorhabditis elegans DOM-3 and human DOM3Z. Deletion of RAI1 confers a growth defect which can be complemented by an additional copy of RAT1 on a centromeric vector or by directing Xrn1p, the cytoplasmic homolog of Rat1p, to the nucleus through the addition of a nuclear targeting sequence. Deletion of RAI1 is synthetically lethal with the rat1-1(ts) mutation and shows genetic interaction with a deletion of SKI2 but not XRN1. Polysome analysis of an rai1 deletion mutant indicated a defect in 60S biogenesis which was nearly fully reversed by high-copy RAT1. Northern blot analysis of rRNAs revealed that rai1 is required for normal 5.8S processing. In the absence of RAI1, 5.8S(L) was the predominant form of 5.8S and there was an accumulation of 3'-extended forms but not 5'-extended species of 5. 8S. In addition, a 27S pre-rRNA species accumulated in the rai1 mutant. Thus, deletion of RAI1 affects both 5' and 3' processing reactions of 5.8S rRNA. Consistent with the in vivo data suggesting that RAI1 enhances RAT1 function, purified Rai1p stabilized the in vitro exoribonuclease activity of Rat1p.

Amino Acid Sequence↗
PubMed2000

Neuroprotective effect of postischemic administration of progesterone in spontaneously hypertensive rats with focal cerebral ischemia.

OBJECT: Exogenous progesterone has been shown to reduce brain edema and ischemia-induced cell damage and to improve physiological and neurological function during the early stage of focal cerebral ischemia. In the present study, the authors assessed the neuroprotective potential of progesterone during the late stage of ischemia in a transient middle cerebral artery (MCA) occlusion model in the rat. METHODS: Forty-eight male spontaneously hypertensive rats were randomly assigned to six groups. Progesterone was dissolved in dimethyl sulfoxide (DMSO). In four groups of rats, the dissolved progesterone (4 mg/kg or 8 mg/kg) was administered for 2 or 7 days after ischemia. In two control groups DMSO was administered for 2 or 7 days after ischemia. Occlusion of the MCA was induced by insertion of an intraluminal suture, and reperfusion was accomplished by withdrawal of the suture. Treatment was initiated on reperfusion, which followed 2 hours of MCA occlusion, and continued once a day. Lesion volume, neurological deficit, and body weight loss were measured 2 or 7 days after ischemia, depending on the animal group. Treatment with a high dose of progesterone (8 mg/kg) resulted in reductions in lesion size, neurological deficits, and body weight, compared with control rats. CONCLUSIONS: Administration of progesterone to male rats 2 hours after MCA occlusion reduces ischemic brain damage and improves neurological deficit even 7 days after ischemia.

Analysis of Variance↗
PubMed2000

Coronary artery stents in the treatment of ischaemic heart disease: a rapid and systematic review.

BACKGROUND: Coronary artery stents are prosthetic linings inserted into coronary arteries via a catheter to widen the artery and increase blood flow to ischaemic heart muscle. They are used in the treatment of ischaemic heart disease (IHD). IHD is a major cause of morbidity and mortality (123,000 deaths per annum) in the UK and a major cost to the NHS. Clinical effects of IHD include subacute manifestations (stable and unstable angina) and acute manifestations (particularly myocardial infarction [MI]). Treatment includes attention to risk factors, drug therapy, percutaneous invasive interventions (PCIs) (including percutaneous transluminal coronary angioplasty [PTCA] and stents) and coronary artery bypass graft surgery (CABG). In the last decade there has been a steady and significant increase in the rate of PCIs for IHD. In the UK, rates per million population increased from 174 in 1991 to 437 in 1998. Stents are now used in about 70% of PCIs. Data from the rest of Europe suggest there is potential for PCI and stent rates to increase considerably. In the UK there is evidence of under-provision and inequity of access to revascularisation procedures. OBJECTIVES: The following questions were addressed. 1. What are the effects and effectiveness of elective stent insertion versus PTCA in subacute IHD, particularly stable angina and unstable angina? 2. What are the effects and effectiveness of elective stent insertion versus CABG in subacute IHD, particularly stable angina and unstable angina? 3. What are the effects and effectiveness of elective stent insertion versus PTCA in acute MI (AMI)? 4. What are best estimates of UK cost for elective stent insertion, PTCA and CABG in the circumstances of review questions 1 to 3? 5. What are best estimates of cost-effectiveness and cost-utility for elective stent insertion relative to PTCA or CABG in the circumstances of review questions 1 to 3? METHODS: A systematic review addressing the objectives was undertaken. DATA SOURCES: A search was made for RCTs comparing stents (inserted during a PTCA procedure) with PTCA alone or with CABG in any manifestation of IHD. The search strategy covered the period from 1990 to November 1999 and included searches of electronic databases (MEDLINE, EMBASE, BIDS ISI, The Cochrane Library), Internet sites, and hand-searches of cardiology conference abstracts and 1999 issues of cardiology journals. Lead researchers and local clinical experts were contacted. Manufacturers' submissions to the National Institute for Clinical Excellence were searched. The search strategy was expanded to look for relevant economic analyses and information to inform the economic model (including searching MEDLINE, the NHS Economic Evaluation Database and the Database of Abstracts of Reviews of Effectiveness). Searches focused on research that reported costs and quality of life data associated with IHD and interventional cardiology. STUDY SELECTION: For the review of clinical effectiveness, inclusion criteria were: (i) RCT design; (ii) study population comprising adults with IHD in native or graft vessels (including patients with subacute IHD or AMI); (iii) procedure involving elective insertion of coronary artery stents; (iv) elective PTCA (including PTCA with provisional stenting) or CABG as comparator; (v) outcomes defined as one or more of: combined event rate (or event-free survival), death, MI, angina, target vessel revascularisation, CABG, repeat PTCA, angiographic outcomes; (vi) trials that had closed and reported results for all or almost all recruited patients. For the economic evaluation, studies of adults with IHD were included if they were of the following types: studies reporting UK costs; comparative economic evaluation combining both costs and outcomes; economic evaluations reporting costs and outcomes separately for the years 1998 and 1999 (to ensure current practice was included).(ABSTRACT TRUNCATED)

Adult↗
PubMed1999

The Toll-like receptor 2 is recruited to macrophage phagosomes and discriminates between pathogens.

Macrophages orchestrate innate immunity by phagocytosing pathogens and coordinating inflammatory responses. Effective defence requires the host to discriminate between different pathogens. The specificity of innate immune recognition in Drosophila is mediated by the Toll family of receptors; Toll mediates anti-fungal responses, whereas 18-wheeler mediates anti-bacterial defence. A large number of Toll homologues have been identified in mammals, and Toll-like receptor 4 is critical in responses to Gram-negative bacteria. Here we show that Toll-like receptor 2 is recruited specifically to macrophage phagosomes containing yeast, and that a point mutation in the receptor abrogates inflammatory responses to yeast and Gram-positive bacteria, but not to Gram-negative bacteria. Thus, during the phagocytosis of pathogens, two classes of innate immune receptors cooperate to mediate host defence: phagocytic receptors, such as the mannose receptor, signal particle internalization, and the Toll-like receptors sample the contents of the vacuole and trigger an inflammatory response appropriate to defence against the specific organism.

Adaptor Proteins, Signal Transducing↗
PubMed1999

First-episode schizophrenics show normal duration and topography of quasistationary EEG segments as compared to controls, during rest as well as during active tasks.

In patients suffering from chronic schizophrenia, both altered temporospatial structure of the EEG and impaired activation during cognitive tasks have repeatedly been demonstrated. The present study evaluates whether similar abnormalities are present in drug-naive first-episode schizophrenics. The EEGs of 32 schizophrenic patients and of 52 healthy controls were recorded during a simple and a complicated motor task, a simple and a complicated auditory stimulus, and during resting periods between the tasks. The temporospatial characteristics were evaluated by adaptive segmentation of EEG, which decomposes an EEG into temporal segments of quasistationary activity. No differences in the temporal and topographic aspects of the EEGs were found between the first-episode schizophrenic patients and the controls, neither during the resting EEGs nor during active tasks. Moreover, the dynamic course of the EEGs, defined as the alternation between task-related changes of temporospatial patterns and the reappearance of resting patterns, was identical in patients and controls. The present findings suggest that while abnormal EEG power spectra seem a consistent finding in treated as well as in never-treated schizophrenics, altered temporospatial patterns and reduced task-related EEG changes are inconsistent signs.

Adult↗
PubMed1999

Monitoring mRNA decapping activity.

mRNA decapping is a common step shared between two important mRNA decay pathways in yeast, Saccharomyces cerevisiae. To investigate how mRNAs are decapped, we have developed an assay that can be easily used to measure the decapping activity. This assay has been used to isolate yeast strains with altered decapping activities. The results demonstrated that decreased decapping activity in vitro corresponds well with the decapping-deficient phenotype in vivo. This assay has been applied to the purified yeast decapping enzyme Dcp1 protein as well as crude yeast extracts and Xenopus oocyte extracts.

Animals↗
PubMed1999

The lack of associations between rheumatoid arthritis and both nulliparity and infertility.

OBJECTIVES: Rheumatoid arthritis (RA) is an autoimmune disease that occurs more commonly in women and frequently onsets in women of childbearing age. Pregnancy often causes disease remission, with a subsequent flare postpartum. Nulliparity may be a risk factor for RA, but the literature does not consistently report this finding. There may be a production of antibodies in women with RA that could lead to infertility, and subsequent nulliparity, but this has not been proved. We wanted to determine whether there was a relationship between nulliparity, infertility, oral contraceptive use, and adverse pregnancy outcome in women with newly diagnosed RA. METHODS: Through a case control study, using a mailed questionnaire, we compared the fertility and pregnancy outcome histories of 34 women between the ages of 19 and 44 years with recent-onset RA with 68 healthy controls matched for age and marital status. The response rate was 97%. A review of the literature also was performed to study the associations between RA and infertility and nulliparity, using Medline searching key references. RESULTS: We found no association between infertility and the onset of RA. Seventy-one percent of women with RA and 68% of controls had been pregnant. There was a trend toward increased nulliparity in these patients, but the result was not statistically significant (odds ratio [OR], 1.4; P<.6). There were no differences in the number of children (2.6 v. 2.7; P<.6) and parity outcomes in the two groups. Age at first pregnancy was younger in the women with RA (22.6 v. 25.5 years; P<.008), but the education level was higher in the controls (P<.0001), which may explain these differences. Oral contraceptive use was lower in the RA women, but more RA women had long-term use (greater than or equal to 5 years), and neither result was statistically significant. Literature review shows that at best, there are weak negative associations between current estrogen use and RA, and no association with nulliparity and infertility. CONCLUSIONS: It appears that infertility, the number of pregnancies, and pregnancy outcome are not strongly associated with the risk of developing RA in women of childbearing age. However, in this study there may have been selection biases in the women with RA and the controls that differentially could have affected their reproductive outcomes. Thus, a true association could have been missed. Most other published studies find no association between nulliparity and RA.

Adolescent↗
PubMed1999

Malignant melanoma occurring within a previously irradiated area.

The commonest radiation-induced neoplasms are sarcomas. Ionizing radiation is not usually associated with the development of malignant melanoma. We report two patients with malignant melanoma occurring within a previously irradiated area. There is evidence to support radiation in the pathogenesis of melanoma but the family histories, especially in one patient, suggest that genetic mutations may also have played a role, particularly in relation to the short latent period.

Adult↗
PubMed1999

Pilot study of televideo psychiatric assessments in an underserviced community.

OBJECTIVE: The goal of this study was to evaluate patient and physician acceptance of televideo interviews for general psychiatric assessments. METHOD: DSM-III-R diagnoses for axes I and II were made for 40 patients by using the Structured Clinical Interview for DSM-III-R. The patients were then randomly assigned to face-to-face or televideo interviews for general psychiatric assessments conducted by psychiatrists. After each interview the patient and psychiatrist completed measures evaluating perceived rapport and level of satisfaction with the interview. RESULTS: The patients gave high ratings to both satisfaction and ability to develop rapport for both the televideo and face-to-face interviews. The psychiatrists expressed significantly less satisfaction with the televideo interviews, but their actual ratings were positive. CONCLUSIONS: Despite geographic distance, televideo interviews allow a sense of connection between patient and psychiatrist. Lower-cost technology may increase the use of televideo to extend psychiatric service to geographically isolated communities.

Adolescent↗
PubMed1999

Axon repulsion from the midline of the Drosophila CNS requires slit function.

Guidance of axons towards or away from the midline of the central nervous system during Drosophila embryogenesis reflects a balance of attractive and repulsive cues originating from the midline. Here we demonstrate that Slit, a protein secreted by the midline glial cells provides a repulsive cue for the growth cones of axons and muscle cells. Embryos lacking slit function show a medial collapse of lateral axon tracts and ectopic midline crossing of ventral muscles. Transgene expression of slit in the midline restores axon patterning. Ectopic expression of slit inhibits formation of axon tracts at locations of high Slit production and misdirects axon tracts towards the midline. slit interacts genetically with roundabout, which encodes a putative receptor for growth cone repulsion.

Animals↗
PubMed1999

Work practices and histopathological changes in the tenosynovium and flexor retinaculum in carpal tunnel syndrome in women.

We studied 58 women of employable age with the carpal tunnel syndrome in order to determine whether the histological appearances of the carpal tunnel, tenosynovium and flexor retinaculum are influenced by work practices. Age, body mass index and the duration of symptoms did not correlate with the extent of oedema or fibrosis within the tenosynovium. The incidence of abnormality on histological examination of the tenosynovium was the same in employed and unemployed patients (p = 1.0), and was not influenced by the level of repetition (p = 0.89) or force (p = 0.29) of work. Myxoid degeneration within the flexor retinaculum was, however, more common in women undertaking 'high-force' work. Apart from this finding, the results suggest that work practices do not affect tenosynovial thickening, fibrosis or oedema in patients with carpal tunnel syndrome.

Adult↗
PubMed1999

A method for the standardized offline collection of exhaled nitric oxide.

STUDY OBJECTIVES: Exhaled nitric oxide (ENO) is a noninvasive marker of airway inflammation. The purpose of this study was to compare a standardized offline ENO measurement apparatus with a validated on-line method. DESIGN: Asthmatic volunteers (n = 21) had ENO measured by the two following methods: (1) inhalation to total lung capacity (TLC) followed by exhalation at a constant flow (45 mL/s) against a high resistance, while monitoring nitric oxide (NO) and pressure on-line; and (2) inhalation to TLC and exhalation into mylar balloons via an apparatus that included the same resistance and flow rate as used in the on-line method. We also examined NO stability in mylar balloons over 48 h. MEASUREMENTS AND RESULTS: ENO values (given as geometric mean in parts per billion [ppb]; 95% confidence intervals) differed between the on-line method (69.6; 42.6 to 113.8) and the offline method (49.5; 30.9 to 79.3), indicating that the offline method gave lower ENO measures than the on-line method (p < 0.001). Furthermore, this difference between measures increased with increasing mean values. The intraclass correlation coefficient (0.931), however, showed excellent correlation between the on-line and offline methods. Within-subject repeatability, as assessed by the coefficient of repeatability (CR), was good for both the on-line and offline methods (CR, 1.09 and 1.17, respectively). Geometric mean NO concentrations (95% confidence limits) in mylar balloons containing exhalate increased from a baseline of 55.8 ppb (36.9, 84.4) to 64.5 ppb (45.6, 91.1) and 69.5 ppb (51.4, 94.0) at 24 h and 48 h, respectively. CONCLUSIONS: The offline method gave reproducible ENO values that were consistently smaller than, but showed good correlation with, values obtained with on-line ENO collection. This method is suitable for offline collection, but the measured values are not interchangeable with those obtained by on-line measurement.

Airway Resistance↗