PubMed Health⌕ Search

Biomedical subjects

P Hannaford

Publications and source records attributed to P Hannaford.

At least 19 recordsLinked to original sources
PubMed2004

Spectrally resolved femtosecond 2-colour 3-pulse photon echoes: a new spectroscopic tool to study molecular dynamics.

We present a new multidimensional femtosecond spectroscopy technique based on spectrally resolved 2-colour 3-pulse photon echoes for investigating molecular dynamics in a variety of systems including proteins. In this technique the sample is illuminated by two femtosecond 'pump' pulses with wave vectors k1, k2 and wavelength lambda(pump) and a femtosecond 'probe' pulse with wave vector k3 and wavelength lambda(probe). Nonlinear signals are generated in the phase-matching directions k4 = - k1 + k2 + k3 and k6 = - k3 + k1 + k2. These signals are analysed in spectrometers equipped with CCD detectors and the spectra of the signals are recorded for various values of (i) the delay t12 between pulses 1 and 2, (ii) the delay t23 between pulses 2 and 3, and (iii) the wavelengths lambda(pump), lambda(probe). The technique has been used for studying vibrational and electronic dynamics of dye molecules, such as cresyl violet in methanol, and ultra-fast transient processes that occur during the photo-dissociation of carbonmonoxy myoglobin (MbCO) into myoglobin (Mb) and CO.

Algorithms↗
PubMed2003

A cohort study of reproductive risk factors, weight and weight change and the development of diabetes mellitus.

AIMS: Reproductive factors (parity, miscarriages, terminations), oral contraceptive use, hormone replacement therapy, body weight at first pregnancy and weight gain following pregnancy may be associated with a long-term risk of diabetes. The aim of this study is to investigate the independent risks of reproductive factors and body weight for diabetes in later life. METHODS: This is a retrospective cohort study of 1257 parous women who had a first pregnancy between 1951 and 1970. Reproductive history, weight and height were measured at the time of first pregnancy, then assessed by questionnaire in 1997 for all women. A clinical examination and an analysis of blood samples were undertaken for 992 women. The main outcome was incidence of diabetes based on medical history, medication and random glucose measurement. RESULTS: Sixty of the 1257 (4.8%) women developed diabetes. Body mass index at index pregnancy and after 28-48 years follow-up were both significantly associated with risk of diabetes, this increased with greater weight gain. There was a non-significant increased risk of diabetes associated with stillbirths and miscarriages after age and BMI adjustment. CONCLUSIONS: In parous women, higher BMI at index pregnancy, weight gain during follow-up and BMI in later life strongly predict diabetes risk.

Abortion, Induced↗
PubMed2003

Chronic pain and the use of conventional and alternative therapy.

BACKGROUND: Chronic pain is a common problem affecting about half of the general population. This has implications for the utilization of both conventional and alternative health services. OBJECTIVES: The aim of this study was to determine the use of conventional and alternative practitioners and medicines amongst individuals with chronic pain in the community. METHODS: A total of 2422 individuals from a previous population-based survey in the Grampian region of the UK, who agreed to participate in further research, were sent a postal questionnaire. The questionnaire enquired about the presence, type and severity of chronic pain, socio-demographic details, consultations with conventional and alternative practitioners, and the consumption of conventional and alternative medicines. The main outcome measures were the number and frequency of self-reported consultations with GPs, hospital specialists, physical therapists and alternative therapists, and the consumption of prescription, non-prescription and alternative medicines amongst those with chronic pain. RESULTS: Of the 840 individuals reporting chronic pain, 67.2% had seen their GP, 34.0% a hospital specialist, 25.9% a physical therapist and 18.2% an alternative therapist in the preceding year. Prescription medicines had been taken by 58.4%, non-prescription medicines by 57.4% and alternative medicines by 15.7% of individuals with chronic pain. The majority (67.0%) of individuals with chronic pain who sought alternative health care did so in conjunction with conventional health care. Differences in consultations with practitioners and consumption of medicines were found by age, sex, socio-economic status, site of pain and severity of pain. CONCLUSIONS: Individuals with chronic pain consult their GP about their pain more than other practitioners and use conventional medicines more frequently than alternative medicines. Alternative health care is used most commonly in addition to conventional health care, although a small number of individuals with chronic pain use alternative care exclusively. The use of alternative health care amongst those with chronic pain is higher than previously estimated and suggests that the use of these services may be increasing amongst those with chronic pain.

Adult↗
PubMed2003

Precision ablation of dental enamel using a subpicosecond pulsed laser.

In this study we report the use of ultra-short-pulsed near-infrared lasers for precision laser ablation of freshly extracted human teeth. The laser wavelength was approximately 800nm, with pulsewidths of 95 and 150fs, and pulse repetition rates of 1kHz. The laser beam was focused to an approximate diameter of 50microm and was scanned over the tooth surface. The rise in the intrapulpal temperature was monitored by embedded thermocouples, and was shown to remain below 5 degrees C when the tooth was air-cooled during laser treatment. The surface preparation of the ablated teeth, observed by optical and electron microscopy, showed no apparent cracking or heat effects, and the hardness and Raman spectra of the laser-treated enamel were not distinguishable from those of native enamel. This study indicates the potential for ultra-short-pulsed lasers to effect precision ablation of dental enamel.

Bicuspid↗
PubMed2001

The use of a screening questionnaire to identify children with likely asthma.

BACKGROUND: The theory that airway remodeling and possible fixed asthma may result from failure to treat asthma airway inflammation highlights the importance of the early identification of patients with likely asthma. AIM: To identify children with likely asthma whose condition is unknown to the medical services. STUDY: Postal questionnaire survey. SETTING: Children in two general practice populations in 1999. METHOD: Parents completed the postal questionnaire surveys. Two validated scoring systems were used to identify children with 'likely asthma': first, three or more positive responses to five key questions; second, three or more positive responses to the same five questions and one more severe symptom (e.g. exercise-induced wheeze). Questionnaire responses were linked to practice records to determine those with a recorded diagnosis of asthma (ever) or of inhaled medication (past 12 months). RESULTS: Using the first scoring system, 22.5% of children were identified as having likely asthma; more than one-third of these (35.1%) had no corroborative evidence recorded in the practice records. With the second system, 15.5% had likely asthma, a quarter of whom had no corroborative evidence. Depending on the scoring system chosen, between 3.5% and 8% of children in these practices had likely asthma but no corroborative evidence in their records. CONCLUSIONS: Children identified using either of these scoring systems would require full clinical assessment to determine their need for medical intervention. These findings have implications for the allocation of health care resources.

Adolescent↗
PubMed2000

Carpal tunnel syndrome: a nested case-control study of risk factors in women.

Risk factors for the development of carpal tunnel syndrome in women were studied by means of a nested case-control analysis of a prospective cohort study of the health effects of oral contraception in British women. A total of 1,264 women who had a diagnosis of carpal tunnel syndrome reported by their general practitioner between 1968 and 1993 were compared with 1,264 age-matched control women who did not have this diagnosis. The syndrome was associated in older women with some hormonal factors, notably past use of oral contraception (adjusted odds ratio in women aged 40 years and over = 1.38, 95 percent confidence interval: 1.08, 1.76) and more generally with obesity (adjusted odds ratio = 1.68, 95 percent confidence interval: 1.29, 2.18). However, the strongest link was with a previous history of another musculoskeletal complaint for which consultation had been sought (adjusted odds ratio = 1.98, 95 percent confidence interval: 1.61, 2.42). Previous findings of a higher risk in women with diabetes and myxoedema were confirmed, but these contribute only a small proportion of all cases in women. There was no link with psychologic problems or nonmusculoskeletal pain complaints. The previously described increased incidence of carpal tunnel syndrome in women may be partly due to hormonal factors, but is also related to an underlying propensity to musculoskeletal problems and their higher overall frequency in women.

Adult↗
PubMed2000

Health consequences of combined oral contraceptives.

During the past 40 years, combined oral contraceptives (COCs) have become a key component of modern fertility regulation programmes. Today, an estimated 100 million women throughout the world use this method of contraception. With such wide-spread usage, it is perhaps not surprising that COCs have been the subject of extensive medical research.

Adult↗
PubMed2000

Cardiovascular events associated with different combined oral contraceptives: a review of current data.

Studies of combined oral contraceptive (COC) use and cardiovascular disease have been conducted against a background of low cardiovascular risk in young women, changing COC composition and changing user selection and monitoring. Studies of myocardial infarction have found inconsistent results, possibly because of differences in the prevalence of risk factors (particularly smoking and raised blood pressure) in the populations studied. In the absence of a history of smoking and other conventional risk factors, current users of modern COCs probably do not have an increased risk of myocardial infarction. Neither are former users at risk. Evidence for important differences in the risk of myocardial infarction between formulations is weak and contradictory. Current users of low estrogen dose COCs have a small increased risk of ischaemic stroke although most of the risk occurs in women with other risk factors (notably smoking, hypertension and probably a history of migraine). Former users of COCs do not have an increased risk of ischaemic stroke. There is insufficient information to determine whether major differences in the risk of ischaemic stroke exist between products. Current users appear to have a modestly elevated risk of haemorrhagic stroke, mainly in women older than 35 years; former users do not. Data examining the risk of haemorrhagic stroke in current COC users with other risk factors are very sparse, as are those relating to the haemorrhagic stroke risk associated with particular COCs. Numerous studies have found, with remarkable consistency, an elevated risk of venous thromboembolism among current users of low estrogen dose COCs. The risk is substantially elevated among women with various inherited clotting factor defects. The effects in COC users with other risk factors for venous thrombosis tend to be less pronounced and more inconsistent. A number of studies have found higher relative risks among current users of low estrogen dose COCs containing desogestrel or gestodene, than among users of similar products containing levonorgestrel. A number of explanations, in terms of bias or confounding, have been proposed for these clinically small differences. At best, empirical evidence for these explanations, is weak. The risk of cardiovascular disease of any description is low in COC users. Women can minimise, and possibly eliminate entirely, their arterial risks by not smoking and by having their blood pressure checked before using a COC (in order to avoid its use if raised blood pressure is discovered). Users may decrease their venous thromboembolic risk by their choice of COC preparation although the effects will be modest.

Adult↗
PubMed1999

Mortality associated with oral contraceptive use: 25 year follow up of cohort of 46 000 women from Royal College of General Practitioners' oral contraception study.

OBJECTIVE: To describe the long term effects of the use of oral contraceptives on mortality. DESIGN: Cohort study with 25 year follow up. Details of oral contraceptive use and of morbidity and mortality were reported six monthly by general practitioners. 75% of the original cohort was "flagged" on the NHS central registers. SETTING: 1400 general practices throughout Britain. SUBJECTS: 46 000 women, half of whom were using oral contraceptives at recruitment in 1968-9. Median age at end of follow up was 49 years. MAIN OUTCOME MEASURES: Relative risks of death adjusted for age, parity, social class, and smoking. RESULTS: Over the 25 year follow up 1599 deaths were reported. Over the entire period of follow up the risk of death from all causes was similar in ever users and never users of oral contraceptives (relative risk=1.0, 95% confidence interval 0.9 to 1.1; P=0.7) and the risk of death for most specific causes did not differ significantly in the two groups. However, among current and recent (within 10 years) users the relative risk of death from ovarian cancer was 0.2 (0.1 to 0.8; P=0.01), from cervical cancer 2.5 (1.1 to 6.1; P=0.04), and from cerebrovascular disease 1.9 (1.2 to 3.1, P=0.009). By contrast, for women who had stopped use >/= 10 years previously there were no significant excesses or deficits either overall or for any specific cause of death. CONCLUSION: Oral contraceptives seem to have their main effect on mortality while they are being used and in the 10 years after use ceases. Ten or more years after use ceases mortality in past users is similar to that in never users.

Cause of Death↗
PubMed1999

Assessment of a simple scoring system applied to a screening questionnaire of asthma in children aged 5-15 yrs.

The aim of the present study was to validate a simple scoring system using a parent-completed screening questionnaire to identify children aged 5-15 yrs who may have asthma. A stratified random sample of 157 children of 1,808 whose parents had answered a postal respiratory questionnaire underwent detailed clinical evaluation. The results were reviewed by three independent paediatricians whose opinions were combined to reach, for each child, decisions regarding three standards: 1) "possible asthma" defined as >50% likelihood of having asthma; 2) "possible asthma" defined as meriting a clinical trial of asthma medication; and 3) "probable asthma" defined as >90% likelihood of having asthma. The combined decisions were compared to three sets of questionnaire scores, in order to determine the positive predictive value, sensitivity and specificity of each set in identifying children with probable/possible asthma. The three sets of chosen questionnaire scores all had positive predictive values of 79-96% for predicting possible asthma, using either the combined expert opinion ">50% likelihood of asthma" or that of "warrants a trial of treatment" as the definition. This suggests that a low proportion of false positives would be obtained were this scoring system to be used for a screening programme. The combined decision >90% chance of asthma could be used as a means of estimating prevalence of asthma in the survey. When used for this, the prevalence of asthma in the surveyed population was 18.8% (95% confidence interval 13.1-26.3). In conclusion, the present scoring system, based on a simple respiratory questionnaire, provides a valid method of identifying children likely to have asthma, and who, if unknown to the medical services, would benefit from clinical review.

Adolescent↗
PubMed1999

Shaping the future: a primary care research and development strategy for Scotland.

Primary care is at the centre of the National Health Service (NHS) in Scotland; however, its R & D capacity is insufficiently developed. R&D is a potentially powerful way of improving the health and well-being of the population, and of securing high quality care for those who need it. In order to achieve this, any Scottish strategy for primary care R&D should aim to develop both a knowledge-based service and a research culture in primary care. In this way, decisions will be made based upon best available evidence, whatever the context. Building on existing practice and resources within primary care research, this strategy for achieving a thriving research culture in Scottish primary care has three key components: A Scottish School of Primary Care which will stimulate and co-ordinate a cohesive programme of research and training. A comprehensive system of funding for training and career development which will ensure access to a range of research training which will ensure that Scotland secures effective leadership for its primary care R&D. Designated research and development practices (DRDPs) which will build on the work of existing research practices, in the context of Local Health Care Co-operatives (LHCCs) and Primary Care Trusts (PCTs), to create a co-operative environment in which a range of primary care professionals can work together to improve their personal and teams' research skills, and to support research development in their areas. A modest investment will create substantial increases in both the quality and quantity of research being undertaken in primary care. This investment should be targeted at both existing primary care professionals working in service settings in primary care, LHCCs and PCTs, and at centres of excellence (including University departments). A dual approach will foster collaboration and will allow existing centres of excellence both to undertake more primary care research and to support the development of service based primary care professionals in their research. Resources should be distributed equitably, taking into account demography, geography and the health needs of patients in Scotland. The strategy and its components must be seen as a whole. The Scottish School of Primary Care will stimulate and co-ordinate both research and training programmes. DRDPs will become research active and will participate in School-led training and research, and will contribute to research programmes. Comprehensive funding for training and career development will ensure that staff have the skills to participate in both DRDPs and in the School's activities. Thus, inadequate commitment to any one component of the strategy will mean that other components will be less successful. Commitment to all three components will maximise the chances of success.

Health Services Research↗
PubMed1998

The collection and interpretation of epidemiological data about the cardiovascular risks associated with the use of steroid contraceptives.

A variety of epidemiological approaches have been used to assess the safety of steroid contraceptives. Each study design has its own strengths and weaknesses, especially with respect to susceptibility to bias and confounding. Randomized controlled trials provide the strongest evidence of a cause and effect relationship, but the low incidence of cardiovascular disease in women of reproductive age precludes the use of this study design to examine these clinical endpoints. Consequently, observational cohort and case-control studies have provided the most useful clinical information about the main cardiovascular effects of steroid contraceptives. Data from epidemiological research need to be interpreted carefully taking into consideration which of the potential biases or sources of confounding are likely to have affected a particular study, and what effect these may have on any inferences from the study. Additional factors that need to be considered before deciding whether a causal relationship exists include evidence that the exposure preceded the disease, the strength of association, consistency of findings with other studies, presence of dose gradients, and agreement with animal or laboratory research. Even if a casual link is thought to be plausible, the public health implications may be minimal; absolute (attributable) risks are required in order to assess these. An understanding of these epidemiological issues will enable clinicians to advise their clients whether steroid contraceptives alter the risk of cardiovascular disease and, if so, the clinical significance of such changes.

Cardiovascular Diseases↗
PubMed1998

Relationship between exhaled nitric oxide and childhood asthma.

The purpose of the study was to determine if exhaled nitric oxide levels in children varied according to their asthmatic and atopic status. Exhaled nitric oxide was measured in a sample of 93 children attending the North West Lung Centre, Manchester, United Kingdom, for the clinical evaluation of a respiratory questionnaire being developed as a screening tool in general practice. The clinical assessment included full lung function, skin prick testing, and exercise challenge. Children were said to be asthmatic either by consensus decision of three independent consultant pediatricians, who reviewed all the clinical results except the nitric oxide measurements, or by positive exercise test. Atopic asthmatic children had higher geometric mean exhaled nitric oxide levels (consensus decision, 12.5 ppb [parts per billion] 95% CI, 8.3 to 18. 8; positive exercise test, 12.2 ppb 95% CI, 7.6 to 19.7) than did nonatopic asthmatic children (3.2 ppb 95% CI, 2.3 to 4.6; 3.2 ppb 95% CI, 2.0 to 5.0), atopic nonasthmatic children (3.8 ppb 95% CI, 2. 7 to 5.5; 5.7 ppb 95% CI, 4.1 to 8.0), or nonatopic nonasthmatic children (3.4 ppb 95% CI, 2.8 to 4.1; 3.5 ppb 95% CI, 3.0 to 4.1). Thus, exhaled nitric oxide was raised in atopic asthmatics but not in nonatopic asthmatics, and these nonatopic asthmatics had levels of exhaled nitric oxide similar to those of the nonasthmatics whether atopic or not.

Adolescent↗