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Biomedical subjects

P Walker

Publications and source records attributed to P Walker.

At least 19 recordsLinked to original sources
PubMed2006

Cervical screening in HIV-positive women: characteristics of those who default and attitudes towards screening.

OBJECTIVES: To determine the characteristics of HIV-positive women who undergo cervical screening and to identify negative attitudes and experiences of these women to screening and the factors associated with these. METHODS: We compared the Royal Free Cohort data from 59 newly diagnosed HIV-infected women, 31 of whom did and 28 of whom did not attend for cervical screening in 2001, and from 227 women under active cervical screening follow-up (at least one cervical screen since June 2001) and 88 HIV-infected women lost to follow-up (not screened since January 2001). Attitudes to screening were investigated with the aid of a questionnaire given to all women attending clinic who had had a previous colposcopy. RESULTS: Of the 59 newly HIV diagnosed women, 31 (53%) underwent cervical screening. These 31 women were more likely to be heterosexual (100 vs 89%, P=0.05), to have lower median viral loads (< 50 vs 3210 HIV-1 RNA copies/mL) and to be receiving antiretrovirals (ARVs) (74 vs 54%, P=0.1) than those not screened. Of the 315 women who had at least one screen, 72% returned for further follow-up. There were no differences in age or ethnicity between these groups. Those under active follow-up had a higher CD4 count (P=0.04) and lower viral load (P=0.0001) at their last visit. They were also more likely to be on highly active antiretroviral therapy (HAART) (68 vs 52%, P=0.006). A total of 78 of 104 questionnaires (75%) were returned. Women participating in the questionnaire study were mainly of back ethnicity (68%), did not speak English as their first language (59%) and were taking ARVs (76%). Most agreed that regular smears and colposcopy were valuable. Women of white ethnicity, and those speaking English as a first language, were more likely to dislike colposcopy compared with those of nonwhite ethnicity (87 vs 25%, respectively, P=0.0007) and not speaking English as a first language (74 vs 26%, respectively, P=0.002). Those of white ethnicity were more likely to find smears and colposcopy painful (60 and 73%) compared with those of black ethnicity (46 and 51%, P=0.47 and 0.28, respectively). CONCLUSIONS: Our results suggest that women on HAART with better disease control, older women, and those of black African ethnicity are more likely to take up cervical screening. Cervical screening experience varies by ethnicity and language.

Adult↗
PubMed2006

Bristol COPD Knowledge Questionnaire (BCKQ): testing what we teach patients about COPD.

Health professionals recommend education of patients about COPD. There is no satisfactory instrument to measure their knowledge and therefore to assess the results of education. A multiple-choice questionnaire (BCKQ) has been designed and tested. Each of 13 topics contains five statements for which there is a right or wrong answer. Its validity and consistency has been assessed, and the test re-test reliability and responsiveness measured after an interval of eight weeks. A copy of the multiple-choice questionnaire is given in the Appendix. The questionnaire was judged by patients and health professionals to have good content and face validity. It has good internal consistency for the 65 items. (Cronbach's alpha 0.73). It can be completed and scored within twenty minutes. The average score in subjects who had not received prior education was 54.7%. In a group not receiving education there was good test-retest reliability (r = 0.71). Following an eight-week education programme there was a significant improvement of 18.3 percentage points, and most of the increase was maintained for six months without any further formal education. BCKQ is suitable for both clinical and research purposes. It will test knowledge that is appropriate for COPD patients and can be used as an assessment tool for individual patients, or as a broad cross-sectional survey instrument. It will enable the effectiveness of education to be assessed and will be of value in developing and comparing different educational interventions.

Aged↗
PubMed2005

Intravenous aminophylline in patients admitted to hospital with non-acidotic exacerbations of chronic obstructive pulmonary disease: a prospective randomised controlled trial.

BACKGROUND: Intravenous aminophylline is commonly used in the treatment of exacerbations of chronic obstructive pulmonary disease (COPD), despite limited evidence for its efficacy and known risks of toxicity. We hypothesised that adding intravenous aminophylline to conventional treatment would not produce clinically important changes in the speed of spirometric or symptomatic recovery or shorten hospital stay in patients with exacerbations of COPD. METHODS: Eighty patients admitted to hospital with non-acidotic exacerbations of COPD were recruited at admission to a randomised, double blind, placebo controlled study comparing intravenous aminophylline 0.5 mg/kg/hour after an appropriate loading dose with an equivalent volume of 0.9% saline. The primary outcome was the change in post-bronchodilator forced expiratory volume in 1 second (FEV(1)) over the first 5 days of the admission. Secondary end points were changes in self-reported breathlessness, arterial blood gas tensions, forced vital capacity (FVC), and length of hospital stay. RESULTS: There was no difference in the post-bronchodilator FEV(1) over the first 5 days between the aminophylline and placebo groups. In the aminophylline group, 2 hours of treatment produced a small but significant rise in arterial pH (p = 0.001) and a fall in arterial carbon dioxide tension (p = 0.01) compared with placebo treatment. There were no differences in the severity of breathlessness, post-bronchodilator FVC, or length of hospital stay between the groups. Nausea was a more frequent side effect in the aminophylline group (46% v 22%; p<0.05), but palpitations and headache were noted equally in both groups. CONCLUSIONS: Although intravenous aminophylline produced small improvements in acid-base balance, these did not influence the subsequent clinical course. No evidence was found for any clinically important additional effect of aminophylline treatment when used with high dose nebulised bronchodilators and oral corticosteroids. Given its known toxicity, we cannot therefore recommend the use of intravenous aminophylline in the treatment of non-acidotic COPD exacerbations.

Aged↗
PubMed2005

Mortality experience of male workers at a UK tin smelter.

BACKGROUND: Between 1937 and 1991, Capper Pass and Sons Limited operated a tin smelter complex in North Humberside, UK, at which employees were potentially exposed to a number of substances, including lead, arsenic, cadmium and natural series radionuclides. Decommissioning and site clearance continued until 1995. Between 1967 and 1995 the company was a subsidiary of Rio Tinto plc. AIMS: The aim was to identify any significant excess, or deficits, in mortality among former employees that might be attributable to factors associated with occupation. METHODS: We defined a cohort of 1462 males who had been employed for at least 12 months between 1/11/1967 and 28/7/1995, followed-up through to 31/12/2001. The mortality of the cohort was compared against that expected for both national and regional populations. RESULTS: Mortality from all causes and all cancers did not differ from that expected. Mortality from ischaemic heart disease showed a deficit and mortality from lung cancer showed a statistically significant excess. Mortality from smoking related diseases other than lung cancer showed a non-significant deficit. CONCLUSIONS: The pattern of lung cancer mortality is consistent with the hypothesis that the risk of lung cancer has been enhanced by occupational exposure to one or more carcinogens, the effect of which diminishes with time since exposure. The deficit in ischaemic heart disease may be attributed to a protective effect from manual labour. The results provide no evidence for attribution of other excess or deficits in mortality to factors associated with employment.

Adult↗
PubMed2004

[STEP--standardized assessment of elderly people in primary care].

BACKGROUND: There is a need for a standard preventive assessment scheme, which is effective, feasible and acceptable throughout European primary care. METHODS: A consensus based guideline including systematic reviews of the evidence was done by an expert panel of general practitioners (core group) and epidemiologists / geriatricians from seven European countries. RESULTS: The Step group identified 8 health domains to be considered in a preventive assessment; client's perspective and attitudes. physical state, functional state, significant symptoms, mental function, social circumstances, medication and primary preventive issues. To select the health areas with a proven preventive potential the strength of scientific evidence and the relevance to primary preventive care was assessed. The final recommendations graded as the preventive primary care impact factor as follows: A1=strongly recommended were hypertension, symptomatic heart failure, urinary incontinence, hearing impairment, vision impairment, falls, breathlessness, depression, dementia, medication review, functional status, activity and physical exercise. A2=recommended: Hypertension over the age of 80, history of myocardial infarction, symptomatic coronary heart disease, atrial fibrillation, history of TIA or stroke, peripheral vascular disease, diabetes, thyroid dysfunction, osteoporosis, lipids, faecal incontinence, weight status, foot problems, oral heath, osteoarthritis, sleeplessness, pain, social circumstances, tobacco and alcohol use, psychological support for patients with chronic disease and (national) immunization & cancer programs. CONCLUSIONS: The rising population of elderly people in Europe gives cause for health care professionals and policy makers to consider optimal ways to preserve health and function in old age. An Evidence based, proactive preventive geriatric assessment can help to promote heath and function in older people.

Age Factors↗
PubMed2004

Criteria for elective admission to the paediatric intensive care unit following adenotonsillectomy for severe obstructive sleep apnoea.

During the period 1997 to 2002, 42 children were electively admitted to the Paediatric Intensive Care Unit at the John Hunter Children's Hospital following adenotonsillectomy for severe obstructive sleep apnoea. Forty children had a preoperative sleep study, of which 33 were complete polysomnograms. Of the 42 children admitted, 35 required no intervention while seven (17%) required an additional intervention beyond supplemental oxygen. Our criteria for elective admission to Paediatric Intensive Care following adenotonsillectomy for severe obstructive sleep apnoea are presented.

Adenoidectomy↗
PubMed2004

Avoidance of laser ignition of endotracheal tubes by wrapping in aluminium foil tape.

A 12-month-old child with a history of prematurity, severe respiratory compromise and failure to thrive required laser supraglottoplasty for severe laryngotracheobronchomalacia. Maintaining adequate oxygenation intraoperatively proved very difficult. Our usual technique with no endotracheal tube was not possible and CO2 lasering was commenced with a polyvinylchloride endotracheal tube in the operative field. The endotracheal tube was struck by the laser but did not ignite. Concern about the very serious morbidity from a laser-induced fire in the airway prompted a search for possible solutions. No commercially available laser-resistant tube is available in small enough diameter to use in an infant. An aluminium foil tape (3M #425) was evaluated and found to be potentially very useful to protect against an airway fire in this uncommon situation.

Aluminum↗
PubMed2004

The effects of margination and red cell augmented platelet diffusivity on platelet adhesion in complex flow.

The effects of platelet margination and enhanced platelet diffusivity, as induced by red blood cells, on the adhesion of platelets, were investigated for a range of haematocrits, under 2D axi-symmetric flow, simulating previous in vitro experiments [Microvasc. Res. 17 (1979), 238-262]. The effect of margination was incorporated via use of an elevated platelet inlet mass fraction, Phie, in a manner similar to that of Wootton [Ann. Biomed. Eng. 29 (2001), 321-329], and a shear and haematocrit dependent platelet diffusivity, according to the model presented by Zydney and Colton [Physico Chem. Hydrodyn. 10 (1988), 77-96] was used. A combination of the two models was required to simulate the deposition of platelets to a collagen coated surface, under the complex flow, which exhibited a recirculation zone and stagnation point. Results obtained showed qualitative agreement with in vitro results, for a range of haematocrits (11-50%), and also showed that the effects of margination were not linearly dependent on haematocrit. Agreement may be improved in future simulations by incorporating the effects of depleted cell concentrations in the vortex which have been observed previously [Phil. Trans. Roy. Soc. (Lond.) B279 (1977), 413-445]. It would also be advantageous to devise a full mathematical description for platelet margination effects as a function of shear rate and haematocrit and a description of the accompanying effect of apparent blood viscosity.

Blood Platelets↗
PubMed2003

A phase 1 study of tazarotene in adults with advanced cancer.

Tazarotene is an acetylenic retinoid which is metabolised to tazarotenic acid and which binds selectively to the retinoid receptors RARbeta and RARgamma. The safety, toxicity and pharmacokinetics of oral tazarotene were determined over 12 weeks of treatment in 34 patients with advanced cancer. Commonly seen toxicities were mucocutaneous symptoms, musculoskeletal pain and headache. Dose-limiting toxicities were hypercalcaemia, hypertriglyceridaemia and musculoskeletal pain. The maximum tolerated dose of tazarotene in this schedule is 25.2 mg day(-1). Plasma concentrations of tazarotenic acid were found to peak rapidly within 1-3 h of dosing and thereafter declined quickly. The C(max) and AUC values on day 0, and weeks 2 and 4 were similar indicating no drug accumulation. The dose-normalised C(max) and AUC values at different dose levels and different study days appeared to be similar indicating linear pharmacokinetics. No objective responses were seen, although stable disease was seen in six out of eight evaluable patients receiving the three highest dose levels of tazarotene (16.8, 25.2 or 33.4 mg day(-1)). We conclude that oral tazarotene is well tolerated when administered daily for 12 weeks, has a favourable toxicity profile compared with other retinoids and merits further investigation as an anticancer therapy.

Adult↗
PubMed2003

Role of ventrolateral periaqueductal gray neurons in the behavioral and cardiovascular responses to contextual conditioned fear and poststress recovery.

We have previously shown that conditioned fear to context increases Fos expression in the caudal ventrolateral region of the periaqueductal gray in the rat. To understand the reason for this activation and its role in the expression of the contextual fear response, the ventrolateral periaqueductal gray was temporarily blocked with bilateral microinjections (0.4 microl) of the GABA agonist muscimol (0.2 mM) or the glutamate antagonist kynurenic acid (0.1 M). Cardiovascular changes and activity were recorded by radio-telemetry and the microinjections were made immediately before testing the conditioned response in the aversive context. Muscimol and kynurenic acid had the same effects: when compared to saline controls, freezing immobility and ultrasonic vocalizations were reduced and replaced by marked locomotor activity, and the increase in heart rate was enhanced; however, the increase in arterial blood pressure remained the same. Interesting changes were also observed when animals were returned to the safe context of their home box after fear (recovery). Basically, the recovery response was either prevented or delayed: instead of returning to resting immobility, the rats remained agitated in their home box with a moderately elevated activity, heart rate and blood pressure. However, the effect of ventrolateral periaqueductal gray blockade on heart rate, arterial pressure and activity did not appear to be specific to the fear response or its recovery because they were also observed in animals returned to the safe context of their home box immediately after injection. The later response was also a recovery response from the milder stress of handling and the injection procedure.We discuss the results by arguing that the ventrolateral periaqueductal gray is involved in the immobility component of both the fear response and poststress recovery responses. To explain our interpretation we consider the findings in relation to the classic descending defence-arousal system and the hyporeactive-hypotensive immobility pattern that has been attributed to the ventrolateral periaqueductal gray. We propose that there is a dual activation of the defence-arousal system and of the ventrolateral periaqueductal gray during fear, with the ventrolateral periaqueductal gray acting as a brake on the defence-arousal system. The role of this brake is to impose immobility and hold off active defence responses such as fight and flight. The result of this combination of arousal and immobility is a hyperreactive freezing immobility associated with ultrasonic vocalizations, and a pressor response accompanied with a slow rise in heart rate. Basically, the animal is tense and ready for action but temporarily immobilised. The ventrolateral periaqueductal gray also acts to impose immobility during recovery; however, this is without coactivation of the defence-arousal system. The result is a return to resting immobility, associated with a return to baseline blood pressure and heart rate. This is an active process that insures a faster and complete return to rest. We conclude that the ventrolateral periaqueductal gray is an immobility center involved not only in the fear response but also in poststress recovery responses.

Animals↗
PubMed2003

The microbiology of glue ear in Australian Aboriginal children.

OBJECTIVE: To study the bacterial cultures of middle ear aspirates from 27 Aboriginal children with otitis media with effusion. METHODS: Standard bacteriological techniques were used to analyse the middle-ear aspirates collected during surgery to insert grommets in 27 Aboriginal children. Swabs of the tympanic membrane were taken for comparison. RESULTS: Forty-five aspirates were collected from 59 myringotomies. Positive cultures were obtained from 19 of these (13 children) with potentially pathogenic organisms identified in 11 children including Staphylococcus, Pseudomonas, Haemophilus influenzae, Moraxella, Achromobacter, Enterobacter and Corynebacterium. CONCLUSION: This is only the second study to look at the bacteria in middle ear effusions in Aboriginal children. Streptococcus pneumoniae was notable in its absence as was found in a previous study.

Age Distribution↗
PubMed2003

Optimizing the frequency of outpatient short-contact dithranol treatment used in combination with broadband ultraviolet B for psoriasis: a randomized, within-patient controlled trial.

BACKGROUND: Recent concerns over the side-effects of psoralen plus ultraviolet (UV) A, immunosuppressive and cytotoxic treatments have led to increased interest in dithranol for treatment of psoriasis. Few studies have investigated how frequently dithranol should be applied. Dithranol-induced inflammation is maximal at 48-72 h, suggesting that daily application of dithranol may not be optimal. OBJECTIVES: To investigate the effectiveness of five times weekly application of short-contact dithranol (SCD) compared with three times weekly application in a dedicated hospital outpatient treatment unit. METHODS: A randomized, within-patient, controlled study was performed. Patients had SCD applied five times weekly to one half of the body, and three times weekly to the other side. Whole-body UVB irradiation was given 5 days a week. Patients were assessed weekly for 8 weeks. Principal outcome measures were percentage reduction in modified Psoriasis Area and Severity Index (mPASI) at the end of study and time to 50% improvement in mPASI score. RESULTS: Twenty-nine patients were recruited; four were excluded from analysis. Mean percentage reduction in mPASI score at the end of study for five times weekly application was 57.3% (95% confidence interval, CI 39.6-75.0%) and for three times weekly application was 55.4% (95% CI 37.8-73.1%; P = 0.34). Mean time to 50% improvement in mPASI for five times weekly treatment was 4.1 weeks and for three times weekly treatment was 4.0 weeks (P = 0.50). There was no difference in the frequency or severity of burning episodes for each side. CONCLUSIONS: This study suggests that three times weekly application of SCD may be as effective as five times weekly when used in conjunction with UVB administered five times weekly. Large studies of whole-body comparisons are warranted to assess further the optimal frequency of SCD and UVB therapy for psoriasis.

Administration, Topical↗
PubMed2001

INSIGHT: a framework for determining impacts of changes in land and water policies.

CSIRO Sustainable Ecosystems is constructing a spatially explicit modelling system capable of exploring alternative land and water policy alternatives against plausible price, cost, and climate scenarios for the next 20 years. INSIGHT will be used to identify the likely impacts of land and water policy options on regional economies and structural adjustment. Flowcharts have been constructed for most of the major crop and pasture and associated economic models for commodities produced in the Lachlan River Catchment of New South Wales. This enabled the most important components and interrelationships within these models to be readily identified. The next step has been to construct models at the regional scale that contain the essential elements of the more-detailed point models. The paper describes the progress to date in describing these models, and how they have been integrated into a coordinated agricultural crop production evaluation system.

Agriculture↗