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Biomedical subjects

J Britton

Publications and source records attributed to J Britton.

At least 55 records · Page 3Linked to original sources
PubMed2003

Oral magnesium and vitamin C supplements in asthma: a parallel group randomized placebo-controlled trial.

BACKGROUND: Epidemiological studies suggest that higher intakes of dietary vitamin C and magnesium may be associated with a reduced risk of asthma. OBJECTIVE: To determine whether vitamin C or magnesium supplements improve the clinical control of asthma in primary care patients. METHODS: A randomized, placebo-controlled, double-blind parallel group trial of 16 weeks supplementation with 1 g/day vitamin C, 450 mg/day magnesium chelate or matched placebo. Three hundred patients aged 18-60 years with physician-diagnosed asthma, controlled with at least one dose of an inhaled corticosteroid daily, were recruited from 24 primary care practices in Nottingham, UK. The main outcome measures were change in forced expiratory volume in 1 s, forced vital capacity, airway responsiveness to methacholine, mean morning and evening peak flow, symptom scores and bronchodilator use, both individually and as a combined summary statistic. RESULTS: There was no evidence of any beneficial effect of either supplement on any outcome measure of asthma control in the primary intention-to-treat analysis, or in an analysis restricted to participants who completed the study. CONCLUSIONS: Regular dietary supplementation with vitamin C or magnesium adds no clinical benefit to current standard therapy of asthma in primary care patients.

Adolescent↗
PubMed2003

Phase II study of primary temozolomide chemotherapy in patients with WHO grade II gliomas.

BACKGROUND: The aim of this study was to assess the efficacy of temozolomide in patients with World Health Organisation (WHO) grade II gliomas treated with surgery alone using imaging and clinical criteria. PATIENTS AND METHODS: Thirty patients with histologically verified WHO grade II gliomas (17 astrocytoma, 11 oligodendroglioma, two mixed oligoastrocytoma) following surgery 2-104 months (median 23 months) after initial diagnosis received temozolomide 200 mg/m(2)/day for 5 days, on a 28-day cycle, for a maximum of 12 cycles or until tumour progression. Median age was 40 years (range 25-68 years). Median follow-up from entry into the study was 3 years [range 23-47 months (for patients alive)]. Objective response was assessed by 3-monthly magnetic resonance imaging and monthly health-related quality of life (HQoL) and clinical assessment. Tumour size was measured as the high signal intensity area on fluid attenuated inversion recovery sequences. Responses were assessed using change in the product of two perpendicular diameters as complete response (CR), partial response (PR), minimal response (MR), stable disease (SD) and progressive disease (PD). RESULTS: Twenty-nine of 30 patients entered into the study were evaluable for response. Three patients had a PR, 14 MR, 11 SD and one PD. Twenty-four patients received 12 cycles of chemotherapy. Of 29 evaluable patients, three discontinued after four, five and six cycles and two after 10 cycles. Nine patients progressed (three during chemotherapy-one PD and two initial SD-and six after completion of chemotherapy); five had evidence of transformation. The 3-year progression-free survival was 66%. Five patients died; the actuarial 3-year survival was 82%. Ninety-six per cent of patients with impaired HQoL had improvement in at least one HQoL domain. There was improvement in 115 of the 207 domains (56%). Fifteen of 28 patients (54%) with epilepsy had reduction in seizure frequency, of whom six became seizure free. Six patients had transient grade III/IV haematological toxicity (11 episodes; 3.5%). CONCLUSIONS: Temozolomide has single-agent activity in patients with WHO grade II cerebral glioma, with modest improvement in quality of life and improvement in epilepsy control. On present evidence, temozolomide cannot be considered as primary therapy without formal comparison with other treatment modalities.

Administration, Oral↗
PubMed2003

Effects of volatile organic compounds, damp, and other environmental exposures in the home on wheezing illness in children.

BACKGROUND: The effects of indoor exposure to volatile organic compounds (VOCs), including formaldehyde, on respiratory health are not clearly understood. The aim of this study was to determine the independent effects of VOCs and other common environmental exposures in the home on the risk and severity of persistent wheezing illness in children. METHODS: Total volatile organic compounds, formaldehyde, nitrogen dioxide, damp (on a four category scale of % wood moisture equivalent), and environmental tobacco smoke (from salivary cotinine) were measured objectively in the homes of 193 children with persistent wheezing illness and 223 controls aged 9-11 years in Nottingham, UK. RESULTS: The risk of wheezing illness was significantly increased only in relation to damp (odds ratio (OR) per increasing category=1.32 (95% confidence interval (CI), 1.00 to 1.75)), and was unrelated to the other exposures measured. Among cases, formaldehyde and damp were associated with more frequent nocturnal symptoms (OR per increasing quartile and category, respectively, 1.45 (1.06 to 1.98) and 1.97 (1.10 to 3.53)), significantly more so in atopic cases, but there was no effect of total volatile organic compounds, nitrogen dioxide, or cotinine. CONCLUSIONS: Domestic volatile organic compounds are not a major determinant of risk or severity of childhood wheezing illness, though formaldehyde may increase symptom severity. Indoor damp increases both the risk and severity of childhood wheezing illness.

Air Pollution, Indoor↗
PubMed2003

Clinical trial comparing nicotine replacement therapy (NRT) plus brief counselling, brief counselling alone, and minimal intervention on smoking cessation in hospital inpatients.

BACKGROUND: Guidelines recommend that smoking cessation interventions are offered in all clinical settings to all smokers willing to make a quit attempt. Since the effectiveness of routine provision of behavioural counselling and nicotine replacement therapy (NRT) to smokers admitted to hospital has not been established, a randomised controlled trial of these interventions given together compared with counselling alone or minimal intervention was performed in hospital inpatients. METHODS: Medical and surgical inpatients who were current smokers at the time of admission were randomised to receive either usual care (no additional advice at admission), counselling alone (20 minute intervention with written materials), or NRT plus counselling (counselling intervention with a 6 week course of NRT). Continuous and point prevalence abstinence from smoking (validated by exhaled carbon monoxide <10 ppm) was measured at discharge from hospital and at 3 and 12 months, and self-reported reduction in cigarette consumption in smokers was assessed at 3 and 12 months. RESULTS: 274 inpatient smokers were enrolled. Abstinence was higher in the NRT plus counselling group (n=91) than in the counselling alone (n=91) or usual care (n=92) groups. The difference between the groups was significant for validated point prevalence abstinence at discharge (55%, 43%, 37% respectively, p=0.045) and at 12 months (17%, 6%, 8%, p=0.03). The respective differences in continuous validated abstinence at 12 months were 11%, 4%, 8% (p=0.25). There was no significant difference between counselling alone and usual care, or in reduction in cigarette consumption between the treatment groups. CONCLUSIONS: NRT given with brief counselling to hospital inpatients is an effective routine smoking cessation intervention.

Administration, Intranasal↗
PubMed2003

Relationship between FEV1 reduction and respiratory symptoms in the general population.

Obstructive airways diseases typically present with dyspnoea, cough and wheeze, and are defined by a reduced forced expiratory volume in one second (FEV1/forced vital capacity (FVC) ratio. Traditionally, however, the severity of chronic obstructive pulmonary disease is graded by the FEV1 % predicted rather than the FEV1/FVC ratio, whilst other potentially valid measures of FEV1 impairment, such as the absolute difference of FEV1 from predicted or the absolute level of FEV1, tend not to be used. The authors have therefore explored the relationship between these different measures of FEV1 impairment and chronic respiratory symptoms in a general population sample. FEV1 and FVC were measured and questionnaire data were obtained on cough, wheeze, shortness of breath and general self-reported breathing trouble in a cross-sectional survey of 2,633 adults aged 18-70 yrs from a district of Nottingham, UK. Odds ratios for each symptom were calculated for declining levels of absolute FEV1, FEV1 % pred, absolute difference of FEV1 from predicted, and FEV1/FVC ratio. They were plotted to display the shape and strength of these relationships before and after adjustment for each other measure. The odds of symptoms increased with declining levels of all FEV1 measures, particularly for wheeze and general breathing trouble. Although this study was not sufficiently powerful to detect significant differences between measures, these relationships were consistently strongest, before and after adjustment, for FEV1 % pred, particularly below a threshold of approximately 75%. The authors conclude that forced expiratory volume in one second % predicted appears to be the measure of airflow impairment most closely associated with chronic respiratory symptoms in the general population.

Adolescent↗
PubMed2002

Experimental demonstration of a controlled-NOT wave-packet gate.

We report the experimental demonstration of a controlled-NOT (CNOT) quantum logic gate between motional and internal-state qubits of a single ion where, as opposed to previously demonstrated gates, the conditional dynamics depends on the extent of the ion's wave packet. Advantages of this CNOT gate over one demonstrated previously are its immunity from Stark shifts due to off-resonant couplings and the fact that an auxiliary internal level is not required. We characterize the gate logic through measurements of the postgate ion state populations for both logic basis and superposition input states, and we demonstrate the gate coherence via an interferometric measurement.

Journal Article↗
PubMed2002

Trapped-ion quantum simulator: experimental application to nonlinear interferometers.

We show how an experimentally realized set of operations on a single trapped ion is sufficient to simulate a wide class of Hamiltonians of a spin-1/2 particle in an external potential. This system is also able to simulate other physical dynamics. As a demonstration, we simulate the action of two nth order nonlinear optical beam splitters comprising an interferometer sensitive to phase shift in one of the interferometer beam paths. The sensitivity in determining these phase shifts increases linearly with n, and the simulation demonstrates that the use of nonlinear beam splitters (n=2,3) enhances this sensitivity compared to the standard quantum limit imposed by a linear beam splitter (n=1).

Journal Article↗
PubMed2002

Is smoking a communicable disease? Effect of exposure to ever smokers in school tutor groups on the risk of incident smoking in the first year of secondary school.

OBJECTIVE: To estimate the effect of joining a first year secondary school tutor group with a high prevalence of ever smoking on the risk of incident smoking in schoolchildren. DESIGN: Cross-sectional questionnaire survey. SETTING: 10 randomly selected secondary schools in Nottinghamshire, UK. PARTICIPANTS: Pupils in years (grades) 7-11 (aged 11-16 years). MAIN OUTCOME MEASURE: Incident smoking in the first year of secondary education, defined as pupils who reported smoking their first cigarette during year 7. RESULTS: Of 6522 pupils (75% of those eligible) who completed the questionnaire, 17% were current smokers and 49% had ever smoked, of whom 23% had started smoking in year 7. Incident smoking in year 7 was more common in girls, in children with parents or siblings who smoke, and in more deprived children, and was independently increased in relation to the proportion of ever smokers in the year 7 tutor group joined by the child (adjusted odds ratio of incident smoking for a child joining a year 7 tutor group in the highest relative to the lowest quartile of ever smoking prevalence 1.45, 95% confidence interval (CI) 1.11 to 1.89). Exposure to ever smokers in year 7 tutor groups also accounted for most of the increased risk of incident smoking associated with socioeconomic deprivation. CONCLUSIONS: The risk of incident smoking in children entering secondary education is independently increased by exposure to other ever smokers in school tutor groups. Incident smoking in adolescents is thus to some extent a communicable disorder, and may be partly preventable by policies that reduce exposure to smoking at school.

Adolescent↗
PubMed2001

Living near a main road and the risk of wheezing illness in children.

The effect of road vehicle traffic pollution on asthma is still not clearly understood. However, any effect is likely to be most marked among those who live within 150 m of a main road, because this is the distance within which concentrations of primary vehicle traffic pollutants are raised above ambient background levels. We have investigated the relation between proximity of the family home to the nearest main road, estimated objectively using geographical information system software, and the risk of wheeze in the past year in a case-control sample of 6,147 primary schoolchildren (age 4 to 11 yr) and a random cross-sectional sample of 3,709 secondary schoolchildren (age 11 to 16 yr) in Nottingham, United Kingdom. Among children living within 150 m of a main road, the risk of wheeze increased with increasing proximity by an odds ratio (OR) of 1.08 (95% confidence interval [CI] 1.00 to 1.16) per 30-m increment in primary schoolchildren, and 1.16 (1.02 to 1.32) in secondary schoolchildren. Most of the increased risk was localized to within 90 m of the roadside. Among primary schoolchildren, effects were stronger in girls than boys (p(interaction) = 0.02). Living within approximately 90 m of a main road is associated with a proximity-related increase in the risk of wheezing illness in children.

Case-Control Studies↗
PubMed2001

Independent effects of intestinal parasite infection and domestic allergen exposure on risk of wheeze in Ethiopia: a nested case-control study.

BACKGROUND: Why asthma is rare in rural subsistence societies is not clear. We tested the hypotheses that the risk of asthma is reduced by intestinal parasites or hepatitis A infection, and increased by exposure to dust-mite allergen or organophosphorus insecticides in urban and rural areas of Jimma, Ethiopia. METHODS: From 12876 individuals who took part in a study of asthma and atopy in urban and rural Jimma in 1996, we identified all who reported wheeze in the previous 12 months, and a random subsample of controls. In 1999, we assessed parasites in faecal samples, Der p 1 levels in bedding, hepatitis A antibodies, serum cholinesterase (a marker of organophosphorus exposure), total and specific serum IgE, and skin sensitisation to Dermatophagoides pteronyssinus in 205 cases and 399 controls aged over 16 years. The effects of parasitosis, Der p 1 level, hepatitis A seropositivity, and cholinesterase concentration on risk of wheeze, and the role of IgE and skin sensitisation in these associations, were analysed by multiple logistic regression. FINDINGS: The risk of wheeze was independently reduced by hookworm infection by an odds ratio of 0.48 (95% CI 0.24-0.93, p=0.03), increased in relation to Der p 1 level (odds ratio per quartile 1.26 [1.00-1.59], p=0.05), and was unrelated to hepatitis A seropositivity or cholinesterase concentration. In the urban population, D pteronyssinus skin sensitisation was more strongly related to wheeze (9.45 [5.03-17.75]) than in the rural areas (1.95 [0.58-6.61], p for interaction=0.017), where D pteronyssinus sensitisation was common, but unrelated to wheeze in the presence of high-intensity parasite infection. INTERPRETATION: High degrees of parasite infection might prevent asthma symptoms in atopic individuals.

Adolescent↗
PubMed2001

Increased risk of allergy associated with the use of kerosene fuel in the home.

Allergic diseases are becoming increasingly prevalent in developing countries, consistent with an environmental etiology associated with affluence or urbanization. We have tested the hypothesis that the risk of allergy is increased by the use of non-biomass fuels (kerosene, gas or electricity) in the home, using data from a survey of the urban population of Jimma, Ethiopia. Questionnaire data on allergic symptoms, domestic fuel use and lifestyle factors were collected from 9844 adults and children, and allergen skin sensitization measured in a subsample of 2372. Use of any non-biomass fuel was reported by 959 individuals (10%), usually in combination with biomass fuel, and was significantly associated with an increased risk of allergic sensitization (age, sex and socio-economic status adjusted odds ratio (95% confidence interval) = 1.78 [1.06 to 2.97]) and wheeze (1.56 [1.07 to 2.26]), rhinitis (2.06 [1.46 to 2.91]) and eczema (2.82 [1.61 to 4.96]) relative to use of biomass fuel only. These effects were predominantly due to kerosene, which was significantly related to all outcomes, and gas, which was strongly related to allergic sensitization. Our findings suggest that domestic combustion of refined fossil fuels increases the risk of allergic sensitization and symptoms, and may have contributed to the increasing prevalence of allergic disease.

Adolescent↗
PubMed2001

Pattern- and growth-linked cell cycles in Drosophila development.

During Drosophila development the cell cycle is subject to diverse regulatory inputs. In embryos, cells divide in stereotypic patterns that correspond to the cell fate map. There is little cell growth during this period, and cell proliferation is regulated at G2/M transitions by patterned transcription of the Cdk1-activator, Cdc25/String. The string locus senses pattern information via a > 40 kb cis-regulatory region composed of many cell-type specific transcriptional enhancers. Later, in differentiated larval tissues, the cell cycle responds to nutrition via mechanisms that sense cellular growth. These larval cell cycles lack mitoses altogether, and are regulated at G/S transitions. Cells in developing imaginal discs exhibit a cycle that is regulated at both G1/S and G2/M transitions. G2/M progression in disc cells is regulated, as in the embryo, by string transcription and is thus influenced by the many transcription factors that interact with string's 'pattern-sensing' control region. G1/S progression in disc cells is controlled, at least in part, by factors that regulate cell growth such as Myc, Ras and phosphatidylinositol-3-kinase. Thus G1/S progression appears to be growth-coupled, much as in the larval endocycles. The dual control mechanism used by imaginal disc cells allows integration of diverse inputs which operate in both cell specification and cell metabolism.

Animals↗
PubMed2001

FLAIR imaging in the follow-up of low-grade gliomas: time to dispense with the dual-echo?

Fluid-attenuated inversion-recovery (FLAIR) imaging has established its utility in neuroimaging. We propose this imaging sequence as a replacement for proton density (PD) and T2-weighted spin-echo sequences in the follow-up of low-grade glioma. 26 MRI examinations of 18 patients with such tumours were reviewed by three neuroradiologists and a neurosurgeon. FLAIR was found to be superior for appreciation of the lesion (91% of studies) and for demonstration of its margin (92%). FLAIR was also better at showing different tumour components, particularly in regions difficult to demonstrate in some planes, such as the vertex in axial imaging. The sequence also defines the postoperative cavity, shows the least amount of susceptibility effect associated with surgical clips, and demonstrates local spread (to white matter tracts, subependymal and capsular) more distinctly. We conclude that FLAIR can replace PD and T2-weighted spin-echo imaging in radiological follow-up of low-grade glioma.

Adult↗
PubMed2000

Dietary vitamin E, IgE concentrations, and atopy.

Vitamin E inhibits IgE responses to allergic stimuli in animals. We investigated the relation between dietary vitamin E intake and serum IgE concentrations and atopy, measured as allergen skin sensitisation, in a random sample of 2633 adults. Higher concentrations of vitamin E intake were associated with lower serum IgE concentrations and a lower frequency of allergen sensitisation. These findings may explain the beneficial effect of dietary vitamin E on the incidence of asthma.

Adult↗