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Biomedical subjects

I A Campbell

Publications and source records attributed to I A Campbell.

At least 19 recordsLinked to original sources
PubMed2006

Extended scaling scheme for critically divergent quantities in ferromagnets and spin glasses.

From a consideration of high temperature series expansions in ferromagnets and in spin glasses, we propose an extended scaling scheme involving a set of scaling formulas which expresses to leading order the temperature (T) and the system size (L) dependences of thermodynamic observables over a much wider range of T than the corresponding one in the conventional scaling scheme. The extended scaling, illustrated by data on the canonical 2d ferromagnet and on the 3d bimodal Ising spin glass, leads to consistency in the estimates of critical parameters obtained from scaling analyses for different observables.

Journal Article↗
PubMed2006

Active surveillance for tuberculosis in Wales: 1996-2003.

AIMS: To estimate the incidence of active tuberculosis (TB) and study the use of chemoprophylaxis for latent TB in children in Wales, and to identify potential areas for improving prevention and management. METHODS: Active surveillance for TB in children aged 0-15 years from July 1996 to December 2003, using the Welsh Paediatric Surveillance Scheme. RESULTS: A total of 232 children, 102 with active TB (2.3 per 100 000) and 130 with latent TB (2.9 per 100 000), were identified. Nearly half (45%) belonged to ethnic minorities (19% were of black African origin), a much higher proportion than the base population. Pulmonary disease was the most common presentation (47%), including six (9%) children who were sputum smear positive. There were 10 cases of disseminated TB, nearly all in white children under 10 years of age. Less than two thirds of eligible children (27/46, 59%) were known to have received BCG immunisation. The source of infection was an adult household contact in most cases, but was not known in 44 cases, particularly among teenagers. Four community outbreaks occurred during the surveillance period, including three in high schools. CONCLUSION: TB incidence in children in Wales remains low, but the epidemiology is changing with an increasing proportion of cases in black African children. The high proportion of patients with disseminated TB is of particular concern. TB in teenagers was often associated with school outbreaks. Many eligible children do not receive BCG immunisation, indicating further scope for prevention.

Adolescent↗
PubMed2004

Five year study of etidronate and/or calcium as prevention and treatment for osteoporosis and fractures in patients with asthma receiving long term oral and/or inhaled glucocorticoids.

BACKGROUND: Glucocorticoids are associated with a reduction in bone density and an increased risk of fracture. Concurrent treatment with bisphosphonates reduces bone loss and may prevent fractures. A randomised study was performed to determine whether treatment with cyclical etidronate and/or calcium for 5 years prevents fractures or reverses/reduces bone loss in patients receiving glucocorticoid treatment for asthma. METHODS: A multicentre, randomised, parallel group comparison of etidronate alone, calcium alone, etidronate + calcium, and no treatment, with stratification according to level of glucocorticoid exposure was carried out in 39 chest clinics in the UK. Three hundred and forty nine postmenopausal female and male outpatients with asthma aged 50-70 years were randomised. The main outcome measures were fractures and changes in bone mineral density (BMD). RESULTS: Overall, 8% of the patients experienced symptomatic fractures and 17.5% developed either a symptomatic fracture and/or a semiquantitative vertebral fracture by the end of 5 years There were no significant differences between the four treatment groups. Comparing etidronate with no etidronate, the rates of new fractures were not significantly different for symptomatic fractures (OR 1.07 (95% CI 0.46 to 2.47)) or for any fractures (OR 0.82 (95% CI 0.45 to 1.47)). For the comparison of calcium with no calcium the corresponding ORs were 1.43 (95% CI 0.62 to 3.33) and 0.91 (95% CI 0.50 to 1.63). In post hoc analysis the effect of etidronate was greater in women than in men (interaction p value 0.02) with the fracture incidence roughly halved (OR 0.39, 95% CI 0.14 to 0.99). Etidronate increased BMD at the lumbar spine by 4.1% (p = 0.001) while calcium had no significant effect. At the proximal femur the effects of treatment were not significant (relative increases etidronate 1.6%; calcium 1.1%). The rate of new fractures in patients with fractures at entry (23.7%) was higher than in those without fractures at entry (14.3%): OR 1.87 (95% CI 1.06 to 3.07). No association was found between change in BMD and new fractures. CONCLUSIONS: In patients receiving glucocorticoids for asthma etidronate significantly increased BMD over 5 years at the lumbar spine but not at the hip and had little if any protective effect against fractures, except possibly in postmenopausal women. The effects of calcium were not significant. Combination treatment had no advantage but increased unwanted effects.

Administration, Inhalation↗
PubMed2003

Pulmonary disease caused by Mycobacterium xenopi in HIV-negative patients: five year follow-up of patients receiving standardised treatment.

The literature concerning the management of pulmonary disease caused by Mycobacterium xenopi is scanty and consists of retrospective reports, mostly of small series of patients. Our aim was to document the clinical features and response to treatment of this rare but challenging disease. Patients were treated in a randomised, multi-centre trial with either rifampicin plus ethambutol or rifampicin, ethambutol and isoniazid. Clinical, bacteriological and radiological progress was monitored at set intervals for 5 years. As no differences emerged between the two groups, the results have been combined to provide this prospective survey. Forty-two patients were studied. Mean age was 65 years, three-quarters were male and two-thirds had other lung disease(s). Sputum was positive on direct smear in 62%. Cavitation was present in 81%, mostly large cavities, and disease was extensive in 38%. Despite good clinical response and little toxicity the death rate was high (69%), but less than 10% died primarily because of the M. xenopi disease. The failure of treatment/relapse rate was 12%. Only 11 (26%) were known to be alive at 5 years of whom seven (17%) were known to be cured. There was no correlation between failure of treatment/relapse and in vitro resistance. Better methods of susceptibility testing and more effective regimens are needed, but it is also evident that improved management of concomitant diseases and better general health will play a major part in increasing survival.

Adult↗
PubMed2002

Ordering in Heisenberg spin glasses.

For five different Heisenberg spin glass systems, torque experiments were performed in applied magnetic fields up to 4 T. The Dzyaloshinski-Moriya random anisotropy strengths, the in-field torque onset temperatures, and the torque relaxation were measured. Critical exponents were estimated independently using a standard protocol. The data are strong evidence for a true spin glass ordered state which survives under high applied magnetic fields; they can be interpreted consistently in terms of a chiral ordering model with replica symmetry breaking as proposed by Kawamura and co-workers.

Journal Article↗
PubMed2002

Controlled trial of three weeks nicotine replacement treatment in hospital patients also given advice and support.

BACKGROUND: Smoking is a major public health issue, estimated as causing 120 000 deaths in the UK per year. Smoking cessation is an important aspect of the treatment of many diseases. Nicotine replacement therapy (NRT) has been shown to increase cessation rates among healthy volunteers and in general practice, but it is not clear whether it has an effect in hospital patients. METHODS: Patients referred by their hospital doctor to the smoking cessation counsellor and who agreed to participate in the study were randomised to receive either NRT given as a nicotine patch daily and a nicotine inhalator on an as needed basis plus advice and support (AS+NRT), or to receive just advice and support (AS). Claims of smoking cessation were validated at 1 week, 3 months, 6 months, and 1 year by carbon monoxide (CO) breath testing. RESULTS: A total of 245 patients were randomised, 136 AS+NRT and 109 AS. There were no significant demographic differences between the two groups at baseline. At 1 year 35 (14%) had sustained cessation confirmed by a CO breath test, 20/136 (15%) AS+NRT and 15/109 (14%) AS, p=0.857. One hundred and ten patients gave up smoking for at least 1 week, 54% AS+NRT and 33% AS (p<0.001). By 6 months there was no significant difference between the two groups (22/136 (16%) AS+NRT and 15/109 (14%) AS). CONCLUSION: In hospital patients NRT, given as regular daily patches plus an inhalator to be used as needed, did not add to the smoking cessation rate achieved at 1 year by regular advice and support, despite significantly increasing the cessation rate at 1 week.

Administration, Cutaneous↗
PubMed2001

Detecting and reducing hospital adverse events: outcomes of the Wimmera clinical risk management program.

OBJECTIVES: To determine if an integrated clinical risk management program that detects adverse patient events in a hospital, analyses their risk and takes action can alter the rate of adverse events. DESIGN: Longitudinal survey of adverse patient events over eight years of progressive implementation of the risk management program. PARTICIPANTS AND SETTING: 49,834 inpatients (July 1991 to September 1999) and 20,050 emergency department patients (October 1997 to September 1999) at a rural base hospital in the Wimmera region of Victoria. MAIN OUTCOME MEASURES: Rates of adverse events detected by medical record review and clinical incident and general practitioner reporting. RESULTS: The annual rate of inpatient adverse events decreased between the first and eighth years of the study from 1.35% of all patient discharges (69 events) to 0.74% (49 events) (P<0.001). Absolute risk reduction was 0.61% (95% CI, 0.23%-0.99%), and relative risk reduction was 44.9% (95% CI, 16.9%-72.9%). The quarterly rate of emergency department adverse events decreased between the first and eighth quarters of monitoring from 3.26% of all attendances (84 events) to 0.48% (12 events) (P< 0.001). Absolute risk reduction was 2.78% (95% CI, 2.04%-3.52%), and relative risk reduction was 85.3% (95% CI, 62.7%-100%). CONCLUSIONS: Adverse patient events can be detected, and their frequency reduced, using multiple detection methods and clinical improvement strategies as part of an integrated clinical risk management program.

Clinical Competence↗
PubMed2001

CD1 genotyping of patients with Mycobacterium malmoense pulmonary disease.

Mycobacterium malmoense is an opportunistic mycobacterium that occasionally causes disease in non-immunosuppressed individuals. As only a few individuals exposed to these organisms actually develop clinical disease, it is possible there is a genetic component to susceptibility. CD1 molecules are capable of presenting antigens from more virulent mycobacteria to T cells; therefore, we were interested in discovering whether recently described polymorphisms in CD1 molecules modulated susceptibility to M. malmoense pulmonary disease. The CD1 system comprises five genes (CD1A, -B, -C, -D, and -E) located on chromosome 1 (1q22-23). CD1 molecules are structurally and functionally related to major histocompatibility complex (MHC) class I molecules and are expressed on dedicated antigen-presenting cells. The primary function of CD1 molecules is to present lipid and glycolipid antigens to T cells. We have developed an allele-specific polymerase chain reaction-sequence-specific primer (PCR-SSP) method of CD1 genotyping. Using this method, we compared the allele and haplotype frequencies of CD1 in 49 HIV-negative patients with M. malmoense pulmonary disease with those in 342 normal controls. The CD1A and CD1E alleles were nominally identified as CD1A*01, CD1A*02, CD1E*01 and CD1E*02, and the control gene frequencies were found to be 5%, 95%, 67% and 33%, respectively. No significant difference was observed between the patient and control cohorts. Positive linkage disequilibrium values of 0.73 were observed between CD1A*02 and CD1E*01 (P<0.0001; chi2 test), and 0.94 between CD1A*01 and CD1E*02 (P<0.0001; chi2 test). Typing was also performed for two previously described CD1D alleles (CD1D*01 and CD1D*02), although only CD1D*01 was detected.

Antigens, CD1↗
PubMed2001

Cost effectiveness of an outpatient multidisciplinary pulmonary rehabilitation programme.

BACKGROUND: Pulmonary rehabilitation programmes improve the health of patients disabled by lung disease but their cost effectiveness is unproved. We undertook a cost/utility analysis in conjunction with a randomised controlled clinical trial of pulmonary rehabilitation versus standard care. METHODS: Two hundred patients, mainly with chronic obstructive pulmonary disease, were randomly assigned to either an 18 visit, 6 week rehabilitation programme or standard medical management. The difference between the mean cost of 12 months of care for patients in the rehabilitation and control groups (incremental cost) and the difference between the two groups in quality adjusted life years (QALYs) gained (incremental utility) were determined. The ratio between incremental cost and utility (incremental cost/utility ratio) was calculated. RESULTS: Each rehabilitation programme for up to 20 patients cost pound 12,120. The mean incremental cost of adding rehabilitation to standard care was pound -152 (95% CI -881 to 577) per patient, p=NS. The incremental utility of adding rehabilitation was 0.030 (95% CI 0.002 to 0.058) QALYs per patient, p=0.03. The point estimate of the incremental cost/utility ratio was therefore negative. The bootstrapping technique was used to model the distribution of cost/utility estimates possible from the data. A high likelihood of generating QALYs at negative or relatively low cost was indicated. The probability of the cost per QALY generated being below pound 0 was 0.64. CONCLUSIONS: This outpatient pulmonary rehabilitation programme produces cost per QALY ratios within bounds considered to be cost effective and is likely to result in financial benefits to the health service.

Cost-Benefit Analysis↗
PubMed2000

Vitamin D receptor gene polymorphisms and susceptibility to Mycobacterium malmoense pulmonary disease.

Polymerase chain reaction using sequence-specific primers was utilized to ascertain the prevalence of 3 polymorphisms of the vitamin D receptor (VDR) gene (FokI F/f, ApaI A/a, and TaqI T/t) in 56 patients with Mycobacterium malmoense pulmonary disease. When compared with 101 controls, M. malmoense patients displayed an increased prevalence of Apa1 A (P=.03; Fisher's exact test), TaqI t (P=.04), and the At VDR haplotype (P=.04), and they displayed a decreased prevalence of FokI f (P=.04). Only 4 (7%) of 56 patients (vs. 29 [28%] of 101 controls) were both positive for FokI f and negative for At (P=.001). This indicates that polymorphisms in the VDR (or in closely linked genes) modulate the susceptibility to M. malmoense and that susceptibility involves multiple genetic and environmental factors.

Disease Susceptibility↗
PubMed2000

Results at 1 year of outpatient multidisciplinary pulmonary rehabilitation: a randomised controlled trial.

BACKGROUND: Pulmonary rehabilitation seems to be an effective intervention in patients with chronic obstructive pulmonary disease. We undertook a randomised controlled trial to assess the effect of outpatient pulmonary rehabilitation on use of health care and patients' wellbeing over 1 year. METHODS: 200 patients with disabling chronic lung disease (the majority with chronic obstructive pulmonary disease) were randomly assigned a 6-week multidisciplinary rehabilitation programme (18 visits) or standard medical management. Use of health services was assessed from hospital and general-practice records. Analysis was by intention to treat. FINDINGS: There was no difference between the rehabilitation (n=99) and control (n=101) groups in the number of patients admitted to hospital (40 vs 41) but the number of days these patients spent in hospital differed significantly (mean 10.4 [SD 9.7] vs 21.0 [20.7], p=0.022). The rehabilitation group had more primary-care consultations at the general-practitioner's premises than did the control group (8.6 [6.8] vs 7.3 [8.3], p=0.033) but fewer primary-care home visits (1.5 [2.8] vs 2.8 [4.6], p=0.037). Compared with control, the rehabilitation group also showed greater improvements in walking ability and in general and disease-specific health status. INTERPRETATION: For patients chronically disabled by obstructive pulmonary disease, an intensive, multidisciplinary, outpatient programme of rehabilitation is an effective intervention, in the short term and the long term, that decreases use of health services.

Aged↗
PubMed2000

Management of spontaneous pneumothorax-a Welsh survey.

The authors sought to determine to what degree current practice by hospital physicians and accident and emergency (A&E) departments in Wales conformed to the British Thoracic Society's guidelines for the management of spontaneous pneumothorax. Questionnaires were posted to all consultants involved in emergency medical admissions in Wales (149 consultant physicians and 23 A&E consultants) of whom 101 (59%) replied. Only 45% used the classification, "small, moderate, or complete" to describe the size of pneumothorax. Just 44% would do as recommended by the British Thoracic Society and discharge an asymptomatic patient with a primary pneumothorax and 34% would discharge a patient with a primary pneumothorax after successful aspiration. Only 20% were prepared to try aspiration initially for a secondary pneumothorax with a complete lung collapse. Thirty four per cent would follow the recommendation to remove a chest drain without prior clamping of the tube 24 hours after bubbling had stopped. In the event of a persistent air leak 69% would refer patients or seek a specialist opinion. Physicians with an interest in respiratory medicine tolerated persistent air leaks for significantly longer than did non-respiratory physicians (median of 7 v 5 days, p=0.001). The survey indicates that fewer than expected consultant physicians and A&E consultants in Wales manage spontaneous pneumothoraces in the way recommended by the guidelines. Physicians with an interest in respiratory medicine tended to comply with these guidelines more than general physicians with interests other than respiratory medicine or A&E consultants but the trend was not significant at the 5% level. It is felt that the guidelines should be disseminated more widely, ensuring that emergency admissions units and A&E departments have copies on display or easily accessible, and that they could be expanded to cover other aspects such as timing for surgery.

Chest Tubes↗
PubMed2000

Smoking cessation.

Explore the source record for details and available documents.

Administration, Cutaneous↗
PubMed1999

Dielectric investigation of the temperature dependence of the nonexponentiality of the dynamics of polymer melts.

Using broad band dielectric spectroscopy (10(-5)-10(9) Hz), combining time domain and frequency domain techniques, we study the temperature dependence of the non-Debye character of the alpha relaxation of polymer melts in the glass transition temperature T(g) range. The alpha relaxation process is described in terms of the Kohlrausch-Williams-Watts relaxation function which has a single parameter beta to characterize the nonexponentiality of the relaxation. At high temperatures, beta remains nearly insensitive to temperature changes, whereas in the vicinity of T(g) a nearly linear increasing of beta with temperature is found. The temperature range where the change of the beta(T) behavior occurs is located for all the polymers investigated around 1.2T(g). Moreover, our results indicate a common value of beta approximately equal to 1/3 at the temperature where the relaxation time diverges. The beta(T) behavior near T(g) is discussed in terms of a "rugged landscape" phase space which allows us to rationalize both the beta(T) behavior observed as well as the similarities of our findings near T(g) with the results reported in simulations on Ising spin glasses and other model systems.

Journal Article↗
PubMed1998

Nutrition in adults with cystic fibrosis.

Improved survival has been associated with better nutritional status in patients with cystic fibrosis (CF). In this study we examined the relationship between nutritional state and other measures of clinical severity in adult patients with CF, attending a regional centre. Eighty-one patients (median age 21 years) were studied. Patients with CF were significantly under weight, compared to healthy individuals but were of similar height. Measurements of lung function, FEV1 and FVC were significantly related to body mass index. Lung function was poorer in patients with chronic pseudomonal infection but body weight and body mass index were not significantly different compared to those without such infection. In 53 patients who were alive 4 years later, FEV1 had declined by -10.5 (2.1)% (P < 0.001) but there was no significant change in body weight 1.5 (6.5) kgs. In 23 patients who died or had lung transplantation the change from 1994 to the date of death or transplantation the FEV1 was reduced by -7.9 (11.2)% (P = 0.004) and body weight -2.8 (4.4) kgs (P < 0.01). In 12 patients who had supplemental enteral feeding, the median increase in body weight was 7|kgs over a period of 12 months. This study confirms that young adult patients with CF are significantly under weight and declining health is associated with significant weight loss. In patients with severe malnutrition significant improvement can be achieved by enteral feeding.

Adolescent↗
PubMed1998

Refined tuberculosis contact tracing in a low incidence area.

Our aim was to evaluate the efficacy of a revised tuberculosis (TB) contact tracing procedure in South Glamorgan whereby routine annual radiological surveillance was abandoned and contacts were either discharged or referred to chest clinic following their initial screening. We reviewed and evaluated data from the TB contact tracing clinic, the Public Health Service Mycobacterium Reference Unit, Cardiff and the Consultant in Communicable Diseases Control, South Glamorgan Health Authority and compared these results with those of our previous study. One hundred and three index cases and 732 contacts were identified. Seven hundred and seven contacts, 526 close and 181 casual, were screened, of whom 102 casuals should not have been. One hundred and sixty-one contacts were given BCG vaccination. Fifty-four contacts were referred to the chest clinic. Seven cases of TB were detected, all in young, unvaccinated, close contacts of pulmonary disease. Twenty-one contacts were given chemoprophylaxis, 20 of whom were close contacts of pulmonary TB and one of extrapulmonary disease. Five contacts who were screened and initially discharged developed TB later: in two the protocol had not been followed and three presented with extrapulmonary TB. Compared with the results of the previous protocol fewer contacts were unnecessarily screened and referrals to the chest clinic increased, as did the number given chemoprophylaxis. The case finding rate is similar to that found prior to the revision of the protocol. The yield from tracing casual contacts continues to be nil. It is very low in contacts of extrapulmonary disease. When the protocol was followed no case of pulmonary TB was missed. The revised protocol seems to be as effective as the previous, more complex protocol. In our area, one of low incidence of TB, screening of casual contacts and of contacts of extrapulmonary TB is not cost-effective. We will concentrate even more on screening close contacts of pulmonary TB.

Adolescent↗