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Biomedical subjects

C R Simpson

Publications and source records attributed to C R Simpson.

6 recordsLinked to original sources
PubMed2002

Coincidence of immune-mediated diseases driven by Th1 and Th2 subsets suggests a common aetiology. A population-based study using computerized general practice data.

BACKGROUND: The recent rise in the prevalence of immune-mediated diseases has been attributed to environmental factors such as a lack of microbial challenge, or dietary change, that deviate the overall balance between mutually antagonistic subsets of T helper (Th) cells. OBJECTIVE: An alternative proposal is that recent environmental changes have resulted in an immune system that is more likely to produce both Th1 and Th2 responses against benign antigens. The prediction of this hypothesis, that Th1 and Th2-mediated diseases are not mutually exclusive, and may be positively associated, is tested here in a whole population. METHODS: Data from General Practices participating in the Scottish Continuous Morbidity Recording (CMR) project were used to determine the coincidence of the major Th2-mediated atopic diseases; asthma, eczema and allergic rhinitis, with the Th1-mediated autoimmune conditions; type I diabetes, rheumatoid arthritis and psoriasis. We also identified the prescription rates of inhaled therapy for asthma in patients with Th1-mediated disease. RESULTS: There was a significant increase in the risk of presenting with a Th1-mediated autoimmune condition in patients with a history of allergic disease (standardized prevalence ratio (95% confidence interval) 1.28 (1.18-1.37)). Likewise, the standardized prevalence ratios of presenting with either eczema (1.67 (1.48-1.87)) or allergic rhinitis (1.22 (1.02-1.44)) were significantly increased in subjects with a history of Th1-mediated disease. There was a particularly strong association between current psoriasis and current eczema (standardized prevalence ratio ofpsoriasis in subjects with eczema 2.88, 95% confidence interval (CI) 2.38-3.45). There was also a significant increase in prescriptions for inhaled asthma therapy in patients with Th1 disease. CONCLUSION: It is concluded that Th1- and Th2-mediated diseases are significantly associated in a large General Practice population. This finding supports the proposal that autoimmune and atopic diseases share risk factors that increase the propensity of the immune system to generate both Th1- and Th2-mediated inappropriate responses to non-pathological antigens.

Adolescent↗
PubMed2000

Respiratory morbidity in primary care. A population based study, using practices from the Scottish Continuous Morbidity Recording Research Database.

OBJECTIVE: To elucidate the patterns and period prevalences of respiratory disease with special reference to asthma (including wheezing) in view of its increasing reported prevalence. DESIGN: Observational study based on prospectively entered data. SETTING/SUBJECTS: Fifty five Continuous Morbidity Recording (CMR) practices with 290,000 patients located throughout Scotland. RESULTS: Respiratory problems accounted for a large proportion (17%) of total general practice workload. Upper respiratory tract infections were the commonest presentation in pre-school children, followed by asthma but with an ever increasing proportion of consultations for bronchitis and lower respiratory tract infections with advancing adult age. There was no significant correlation between deprivation and the incidence of asthma. CONCLUSIONS: Observed rates and patterns of disease for CMR practices, were similar to previously reported studies. The large number of presentations by patients in early childhood with minor respiratory illnesses and in particular upper respiratory tract infections are likely to reflect a heightened level of parental anxiety where interpretation of clinical signs and separation of simple and significant illness can be difficult. CMR has also been shown to be of use in helping to investigate links between deprivation and disease incidence or severity. Potential uses for CMR include the study of whole population morbidity and utilisation of primary care services.

Database Management Systems↗
PubMed1998

Generating the Snellen Chart by computer.

The Snellen Chart is the eye chart that is commonly used to measure visual acuity. The chart has combinations of nine different letters in eleven different lines, each smaller than the one above. Repeated measures of visual acuity may result in chart memorization and false information. Thus, a computer program was written to produce randomized multiple versions of Snellen eye charts. The chart may be changed at some distance from the computer in order to hear subject letter identifications during exercise testing. Different sized letters can also be produced so that the distance from the subject to the chart can vary.

Humans↗
PubMed1998

Near-infrared optical properties of ex vivo human skin and subcutaneous tissues measured using the Monte Carlo inversion technique.

The absorption and transport scattering coefficients of caucasian and negroid dermis, subdermal fat and muscle have been measured for all wavelengths between 620 and 1000 nm. Samples of tissue 2 mm thick were measured ex vivo to determine their reflectance and transmittance. A Monte Carlo model of the measurement system and light transport in tissue was then used to recover the optical coefficients. The sample reflectance and transmittance were measured using a single integrating sphere 'comparison' method. This has the advantage over conventional double-sphere techniques in that no corrections are required for sphere properties, and so measurements sufficiently accurate to recover the absorption coefficient reliably could be made. The optical properties of caucasian dermis were found to be approximately twice those of the underlying fat layer. At 633 nm, the mean optical properties over 12 samples were 0.033 mm(-1) and 0.013 mm(-1) for absorption coefficient and 2.73 mm(-1) and 1.26 mm(-1) for transport scattering coefficient for caucasian dermis and the underlying fat layer respectively. The transport scattering coefficient for all biological samples showed a monotonic decrease with increasing wavelength. The method was calibrated using solid tissue phantoms and by comparison with a temporally resolved technique.

Biophysical Phenomena↗