Blast-related disinhibition and risk seeking in mice and combat Veterans: Potential role for dysfunctional phasic dopamine release

Mild traumatic brain injury (mTBI) caused by exposure to high explosives has been called the "signature injury" of the wars in Iraq and Afghanistan. There is a wide array of chronic neurological and behavioral symptoms associated with blast-induced mTBI. However, the underlying mechanisms are not well understood. Here we used a battlefield-relevant mouse model of blast-induced mTBI and in vivo fast-scan cyclic voltammetry (FSCV) to investigate whether the mesolimbic dopamine system contributes to the mechanisms underlying blast-induced behavioral dysfunction. In mice, blast exposure increased novelty seeking, a behavior closely associated with disinhibition and risk for subsequent maladaptive behaviors. In keeping with this, we found that veterans with blast-related mTBI reported greater disinhibition and risk taking on the Frontal Systems Behavior Scale (FrSBe). In addition, in mice we report that blast exposure causes potentiation of evoked phasic dopamine release in the nucleus accumbens. Taken together these findings suggest that blast-induced changes in the dopaminergic system may mediate aspects of the complex array of behavioral dysfunctions reported in blast-exposed veterans.

Traffic pollution and the incidence of cardiorespiratory outcomes in an adult cohort in London

OBJECTIVES

The epidemiological evidence for adverse health effects of long-term exposure to air and noise pollution from traffic is not coherent. Further, the relative roles of background versus near traffic pollution concentrations in this process are unclear. We investigated relationships between modelled concentrations of air and noise pollution from traffic and incident cardiorespiratory disease in London.

METHODS

Among 211 016 adults aged 40-79 years registered in 75 Greater London practices between 2005 and 2011, the first diagnosis for a range of cardiovascular and respiratory outcomes were identified from primary care and hospital records. Annual baseline concentrations for nitrogen oxide (NO_x), particulate matter with a median aerodynamic diameter <2.5 μm (PM_2.5) attributable to exhaust and non-exhaust sources, traffic intensity and noise were estimated at 20 m² resolution from dispersion models, linked to clinical data via residential postcode. HRs were adjusted for confounders including smoking and area deprivation.

RESULTS

The largest observed associations were between traffic-related air pollution and heart failure (HR=1.10 for 20 μg/m³ change in NO_x, 95% CI 1.01 to 1.21). However, no other outcomes were consistently associated with any of the pollution indicators, including noise. The greater variations in modelled air pollution from traffic between practices, versus within, hampered meaningful fine spatial scale analyses.

CONCLUSIONS

The associations observed with heart failure may suggest exacerbatory effects rather than underlying chronic disease. However, the overall failure to observe wider associations with traffic pollution may reflect that exposure estimates based on residence inadequately represent the relevant pattern of personal exposure, and future studies must address this issue.

Cross-sectional study of ethnic differences in physical fitness among children of South Asian, black African-Caribbean and white European origin: the Child Heart and Health Study in England (CHASE)

OBJECTIVE

Little is known about levels of physical fitness in children from different ethnic groups in the UK. We therefore studied physical fitness in UK children (aged 9-10 years) of South Asian, black African-Caribbean and white European origin.

DESIGN

Cross-sectional study.

SETTING

Primary schools in the UK.

PARTICIPANTS

1625 children (aged 9-10 years) of South Asian, black African-Caribbean and white European origin in the UK studied between 2006 and 2007.

OUTCOME MEASURES

A step test assessed submaximal physical fitness from which estimated VO2 max was derived. Ethnic differences in estimated VO2 max were estimated using multilevel linear regression allowing for clustering at school level and adjusting for age, sex and month as fixed effects.

RESULTS

The study response rate was 63%. In adjusted analyses, boys had higher levels of estimated VO2 max than girls (mean difference 3.06 mL O2/min/kg, 95% CI 2.66 to 3.47, p<0.0001). Levels of estimated VO2 max were lower in South Asians than those in white Europeans (mean difference -0.79 mL O2/min/kg, 95% CI -1.41 to -0.18, p=0.01); levels of estimated VO2 max in black African-Caribbeans were higher than those in white Europeans (mean difference 0.60 mL O2/min/kg, 95% CI 0.02 to 1.17, p=0.04); these patterns were similar in boys and girls. The lower estimated VO2 max in South Asians, compared to white Europeans, was consistent among Indian, Pakistani and Bangladeshi children and was attenuated by 78% after adjustment for objectively measured physical activity (average daily steps).

CONCLUSIONS

South Asian children have lower levels of physical fitness than white Europeans and black African-Caribbeans in the UK. This ethnic difference in physical fitness is at least partly explained by ethnic differences in physical activity.

Fruit, vegetable and vitamin C intakes and plasma vitamin C: cross-sectional associations with insulin resistance and glycaemia in 9-10 year-old children

AIM

To examine whether low circulating vitamin C concentrations and low fruit and vegetable intakes were associated with insulin resistance and other Type 2 diabetes risk markers in childhood.

METHODS

We conducted a cross-sectional, school-based study in 2025 UK children aged 9-10 years, predominantly of white European, South-Asian and black African origin. A 24-h dietary recall was used to assess fruit, vegetable and vitamin C intakes. Height, weight and fat mass were measured and a fasting blood sample collected to measure plasma vitamin C concentrations and Type 2 diabetes risk markers.

RESULTS

In analyses adjusting for confounding variables (including socio-economic status), a one interquartile range higher plasma vitamin C concentration (30.9 μmol/l) was associated with a 9.6% (95% CI 6.5, 12.6%) lower homeostatic model assessment of insulin resistance value, 0.8% (95% CI 0.4, 1.2%) lower fasting glucose, 4.5% (95% CI 3.2, 5.9%) lower urate and 2.2% (95% CI 0.9, 3.4%) higher HDL cholesterol. HbA1c concentration was 0.6% (95% CI 0.2, 1.0%) higher. Dietary fruit, vegetable and total vitamin C intakes were not associated with any Type 2 diabetes risk markers. Lower plasma vitamin C concentrations in South-Asian and black African-Caribbean children could partly explain their higher insulin resistance.

CONCLUSIONS

Lower plasma vitamin C concentrations are associated with insulin resistance and could partly explain ethnic differences in insulin resistance. Experimental studies are needed to establish whether increasing plasma vitamin C can help prevent Type 2 diabetes at an early stage.

Blast exposure causes dynamic microglial/macrophage responses and microdomains of brain microvessel dysfunction

Exposure to blast overpressure (BOP) is associated with behavioral, cognitive, and neuroimaging abnormalities. We investigated the dynamic responses of cortical vasculature and its relation to microglia/macrophage activation in mice using intravital two-photon microscopy following mild blast exposure. We found that blast caused vascular dysfunction evidenced by microdomains of aberrant vascular permeability. Microglial/macrophage activation was specifically associated with these restricted microdomains, as evidenced by rapid microglial process retraction, increased ameboid morphology, and escape of blood-borne Q-dot tracers that were internalized in microglial/macrophage cell bodies and phagosome-like compartments. Microdomains of cortical vascular disruption and microglial/macrophage activation were also associated with aberrant tight junction morphology that was more prominent after repetitive (3×) blast exposure. Repetitive, but not single, BOPs also caused TNFα elevation two weeks post-blast. In addition, following a single BOP we found that aberrantly phosphorylated tau rapidly accumulated in perivascular domains, but cleared within four hours, suggesting it was removed from the perivascular area, degraded, and/or dephosphorylated. Taken together these findings argue that mild blast exposure causes an evolving CNS insult that is initiated by discrete disturbances of vascular function, thereby setting the stage for more protracted and more widespread neuroinflammatory responses.

Long-term exposure to outdoor air pollution and the incidence of chronic obstructive pulmonary disease in a national English cohort

Objectives

The role of outdoor air pollution in the incidence of chronic obstructive pulmonary disease (COPD) remains unclear. We investigated this question using a large, nationally representative cohort based on primary care records linked to hospital admissions.

Methods

A cohort of 812 063 patients aged 40–89 years registered with 205 English general practices in 2002 without a COPD diagnosis was followed from 2003 to 2007. First COPD diagnoses recorded either by a general practitioner (GP) or on admission to hospital were identified. Annual average concentrations in 2002 for particulate matter with an aerodynamic diameter <10 µm (PM₁₀) and <2.5 µm (PM_2.5), nitrogen dioxide (NO₂), ozone and sulfur dioxide (SO₂) at 1 km² resolution were estimated from emission-based dispersion models. Hazard ratios (HRs) per interquartile range change were estimated from Cox models adjusting for age, sex, smoking, body mass index and area-level deprivation.

Results

16 034 participants (1.92%) received a COPD diagnosis from their GP and 2910 participants (0.35%) were admitted to hospital for COPD. After adjustment, HRs for GP recorded COPD and PM₁₀, PM_2.5 and NO₂ were close to unity, positive for SO₂ (HR=1.07 (95% CI 1.03 to 1.11) per 2.2 µg/m³) and negative for ozone (HR=0.94 (0.89 to 1.00) per 3 µg/m³). For admissions HRs for PM_2.5 and NO₂ remained positive (HRs=1.05 (0.98 to 1.13) and 1.06 (0.98 to 1.15) per 1.9 µg/m³ and 10.7 µg/m³, respectively).

Conclusions

This large population-based cohort study found limited, inconclusive evidence for associations between air pollution and COPD incidence. Further work, utilising improved estimates of air pollution over time and enhanced socioeconomic indicators, is required to clarify the association between air pollution and COPD incidence.

Use of Chilled Die Lips to Improve Production Rates in Extrusion of PE

Extrusion rates of polyethylene are limited by the onset of surface defects in the extrudates, which are variously termed sharkskin, melt fracture and so on. Several expedients are effective in relieving this problem. We report here that extrudate surface distortion can be eliminated under some conditions by cooling the die, at normal melt extrusion temperatures. This technique appears to be generally effective for LLDPE and HDPE. The process has been patented [10] for polymers with narrow molecular weight distributions.

Statin use after first myocardial infarction in UK men and women from 1997 to 2006: Who started and who continued treatment?

BACKGROUND AND AIMS

To examine trends in initiation and continuation of statin treatment after myocardial infarction (MI) and their determinants, during a period of increasing usage.

METHODS AND RESULTS

9367 patients aged 30-84 with a first Myocardial Infarction (MI) in 1997-2006 were identified in DIN-LINK, an anonymised, UK primary care database. We assessed statin initiation (prescription within 6 months of MI) and continued therapy (% covered by a prescription on a given day of those prescribed a statin within 6 months). The influences of co-morbidities and socio-economic deprivation (Index of Multiple Deprivation) were examined. Statin initiation increased from 37% for MIs in 1997 to 92% in 2006. Continuation at 1 year remained stable over successive cohorts at approximately 80%, settling to about 76% in patients with 5-10 years follow up. Younger age, affluence, revascularisation in 6 months after MI, and absence of congestive heart failure, predicted higher initiation and continuation; a diagnosis of hypertension or diabetes predicted higher initiation, while smoking was associated with poorer continuation. Men had higher initiation and continued therapy, but these effects were largely explained by their younger age. Type of statin initially prescribed did not influence continued usage.

CONCLUSION

Statin use after MI increased markedly between 1997 and 2006, whilst continued therapy remained high and stable. Importantly, first choice of statin had no effect on continuation. Whilst the high current levels of initiation may have reached a ceiling, increasing continuation rates among smokers, older patients and those from lower socio-economic groups, should remain a priority.

Antipsychotic prescribing to older people living in care homes and the community in England and Wales

OBJECTIVE

Excessive use of antipsychotic medication by older people is an international concern, but there is limited comparative information on their use in different residential settings. This paper describes and compares antipsychotic prescribing to older people in care homes and the community in England and Wales.

METHOD

Analysis of a primary care database (THIN) with 403 259 community and 10 387 care home residents aged 65-104 years in 2008-9.

RESULTS

3677 (0.9%) patients in the community and 2173 (20.9%) in care homes (20.5% in residential homes, 21.7% in nursing homes) received an antipsychotic medication prescription in the last 90 days. Most patients had received prescriptions for more than three months and 60% of prescriptions were for atypical antipsychotics. In patients without severe mental illness, 2367 (0.6%) patients in the community and 1765 (18.2%) in care homes received antipsychotic medication; such prescribing was common for patients with recorded dementia (30.2% in care home, 10.1% in the community). In care homes, younger age and living in the North of England predicted prescribing, but care home type did not. In the community, female gender, increasing age, living in a deprived area and the North predicted prescribing.

CONCLUSIONS

Despite safety concerns, antipsychotic prescribing is markedly higher in care homes than in the community, and strongly associated with dementia in both settings. In England and Wales, we estimate that 54 000 older care home patients and 50 000 community patients receive antipsychotic medication without a diagnosis of severe mental illness with important implications for health and social services.

Cotinine-assessed second-hand smoke exposure and risk of cardiovascular disease in older adults

Objectives

To examine whether second-hand smoke (SHS) exposure measured by serum cotinine is associated with increased coronary heart disease (CHD) and stroke risk among contemporary older British adults.

Design

Prospective population-based study with self-reported medical history and health behaviours. Fasting blood samples were analysed for serum cotinine and cardiovascular disease (CVD) risk markers.

Setting

Primary care centres in 25 British towns in 1998–2001.

Patients

8512 60–79-year-old men and women selected from primary care registers.

Main outcome measures

Fatal and non-fatal myocardial infarction (MI; n=445) and stroke (n=386) during median 7.8-year follow-up.

Main exposure

Observational study of serum cotinine assayed from fasting blood sample using liquid chromatography tandem mass spectrometry method, and self-reported smoking history.

Results

Among 5374 non-smokers without pre-existing CVD, geometric mean cotinine was 0.15 ng/ml (IQR 0.05–0.30). Compared with non-smokers with cotinine ≤0.05 ng/ml, higher cotinine levels (0.06–0.19, 0.2–0.7 and 0.71–15.0 ng/ml) showed little association with MI; adjusted HRs were 0.92 (95% CI 0.63 to 1.35), 1.07 (0.73 to 1.55) and 1.09 (0.69 to 1.72), p(trend)=0.69. Equivalent HRs for stroke were 0.82 (0.55 to 1.23), 0.74 (0.48 to 1.13) and 0.69 (0.41 to 1.17), p(trend)=0.065. The adjustment for sociodemographic, behavioural and CVD risk factors had little effect on the results. The HR of MI for smokers (1–9 cigarettes/day) compared with non-smokers with cotinine ≤0.05 ng/ml was 2.14 (1.39 to 3.52) and 1.03 (0.52 to 2.04) for stroke.

Conclusions

In contemporary older men and women, SHS exposure (predominantly at low levels) was not related to CHD or stroke risks, but we cannot rule out the possibility of modest effects at higher exposure levels.

Physical activity, obesity and cardiometabolic risk factors in 9- to 10-year-old UK children of white European, South Asian and black African-Caribbean origin: the Child Heart And health Study in England (CHASE)

AIMS/HYPOTHESIS

Physical inactivity is implicated in unfavourable patterns of obesity and cardiometabolic risk in childhood. However, few studies have quantified these associations using objective physical activity measurements in children from different ethnic groups. We examined these associations in UK children of South Asian, black African-Caribbean and white European origin.

METHODS

This was a cross-sectional study of 2,049 primary school children in three UK cities, who had standardised anthropometric measurements, provided fasting blood samples and wore activity monitors for up to 7 days. Data were analysed using multilevel linear regression and allowing for measurement error.

RESULTS

Overall physical activity levels showed strong inverse graded associations with adiposity markers (particularly sum of skinfold thicknesses), fasting insulin, HOMA insulin resistance, triacylglycerol and C-reactive protein; for an increase of 100 counts of physical activity per min of registered time, levels of these factors were 12.2% (95% CI 10.2-14.1%), 10.2% (95% CI 7.5-12.8%), 10.2% (95% CI 7.5-12.8%), 5.8% (95% CI 4.0-7.5%) and 19.2% (95% CI 13.9-24.2%) lower, respectively. Similar increments in physical activity levels were associated with lower diastolic blood pressure (1.0 mmHg, 95% CI 0.6-1.5 mmHg) and LDL-cholesterol (0.04 mmol/l, 95% CI 0.01-0.07 mmol/l), and higher HDL-cholesterol (0.02 mmol/l, 95% CI 0.01-0.04 mmol/l). Moreover, associations were broadly similar in strength in all ethnic groups. All associations between physical activity and cardiometabolic risk factors were reduced (albeit variably) after adjustment for adiposity.

CONCLUSIONS/INTERPRETATION

Objectively measured physical activity correlates at least as well with obesity and cardiometabolic risk factors in South Asian and African-Caribbean children as in white European children, suggesting that efforts to increase activity levels in such groups would have equally beneficial effects.

Effect of harvest treatment on biochemical properties of farmed Chinook salmon (Oncorhynchus tshawytscha) tissue during frozen and thawed storage

Two different harvest procedures were employed to investigate whether the method of harvest has an effect upon deteriorative processes that occur during the frozen storage of Chinook salmon (Oncorhynchus tshawytscha) white muscle tissue. These 2 harvest methods, termed "rested"--involving sedation with the aquatic anesthetic AQUI-S and "exercised"--a simulated conventional harvest not involving sedation, contrasted levels of activity of the animal prior to and upon slaughter. Rested and exercised harvesting protocols produced tissue in significantly different postmortem physiological states prior to freezing. Rested, postharvest tissue maintained high metabolic energy stores of ATP and glycogen within the tissue, with low concentrations of tissue and plasma lactate. Exercised tissue exhibited near depleted concentrations of ATP and glycogen and a marked lactate accumulation. In both treatments, no significant change in metabolite levels was seen over a 6-mo storage period at -19 degrees C when tissue was frozen immediately postharvest. Transfer of tissue from frozen temperatures (-80 and -19 degrees C), to refrigerated (-1 and +4 degrees C, respectively) resulted in rapid glycolysis, depleting tissue ATP and glycogen stores and increasing tissue lactate concentrations. Metabolic activity was more significant in rested tissue owing to the larger concentrations of metabolic energy stores and occurred at temperatures between -3 and -1.5 degrees C. During frozen storage (-19 degrees C), there was an increase in the secondary lipid oxidation product TBARS, but harvest treatment had no effect. However, following transfer from frozen to refrigerated (+4 and -1 degrees C) storage, rested tissue showed a significant ability to retard the development of TBARS products.

Secondhand smoke (SHS) exposure is associated with circulating markers of inflammation and endothelial function in adult men and women

AIMS

Secondhand smoke (SHS) exposure is associated with elevated CHD risks. Yet the pathways through which this may operate have not been investigated in epidemiologic studies with objective SHS exposure measures and a wide range of CHD risk factors associated with active smoking. Therefore we investigate associations between SHS exposure and CHD risk factors, to clarify how SHS exposure may raise risk of CHD.

METHODS

Cross-sectional population-based study of 5029 men and women aged 59-80 years from primary care practices in Great Britain. Smoking, behavioural and demographic information was reported in questionnaires; nurses made physical measurements and took blood samples for analysis of serum cotinine and markers of inflammation, hemostasis and endothelial dysfunction.

RESULTS

Active cigarette smokers had lower albumin and higher triglycerides, CRP, IL-6, white cell count, fibrinogen, blood viscosity, factor VIII, VWF and t-PA than non-smokers. Among non-smokers, serum cotinine levels were independently positively associated with CRP, fibrinogen, factor VIII, VWF and t-PA and inversely associated with albumin, after adjustment for age, gender, social and behavioural factors. The differences in CRP, fibrinogen and albumin between cotinine < or =0.05 and >0.7 ng/ml were one-third to one half the size of differences between cotinine < or =0.05 ng/ml and current smokers, but were of similar magnitude for VWF and t-PA.

CONCLUSIONS

Endothelial, inflammatory and haemostatic markers related to CHD risk showed independent associations with SHS exposure in the same direction as those for active smoking. Results aid understanding of the associations between SHS exposure and elevated CHD risks.

Is body mass index before middle age related to coronary heart disease risk in later life? Evidence from observational studies

Objective

Although obesity beginning early in life is becoming more common, its implications for coronary heart disease (CHD) risk in later life remain uncertain. We examined the relationship of body mass index (BMI) before 30 years of age to CHD risk in later life.

Design

Systematic review of published studies relating BMI between age 2-30 years to later CHD risk. Studies were identified using Medline (1950 onwards), Embase (1980 onwards) and Web of Science (1970 onwards) databases (to November 2007).

Measurements

Relative risks (RR) of CHD associated with a 1 standard deviation (SD) increase in BMI (most based on a narrow age-range at measurement) were extracted by 2 authors independently, and combined using random-effect models.

Results

Fifteen studies provided seventeen estimates (731,337 participants, 23,894 CHD events) of the association of early BMI to later CHD outcome. BMI in early childhood (2 to 6 years, 3 estimates) showed a weak inverse association with CHD risk (RR 0.94, 95% CI 0.82-1.07). BMI in later childhood (7 to <18 years, 7 estimates) and BMI in early adult life (18-30 years, 7 estimates) were both positively related to later CHD risk (RR 1.09, 95% CI 1.00-1.20; RR 1.19, 95% CI 1.11-1.29 respectively). However, there was considerable statistical heterogeneity between study estimates. Results were unaffected by adjustment for social class and/or cigarette smoking, blood pressure and/or total cholesterol, in studies with available data. Gender and year of birth (1900-1976) had little effect on the association.

Conclusions

BMI is positively related to CHD risk from childhood onwards; the associations in young adults are consistent with those observed in middle age. Long-term control of BMI from childhood may be important to reduce the risk of CHD.

What factors are associated with physical activity in older people, assessed objectively by accelerometry?

OBJECTIVES

To assess physical activity (PA) levels measured objectively using accelerometers in community-dwelling older people and to examine the associations with health, disability, anthropometric measures and psychosocial factors.

DESIGN

Cross-sectional survey.

SETTING

Single general practice (primary care centre), United Kingdom.

PARTICIPANTS

Random selection of 560 community-dwelling older people at least 65 years old, registered with the practice. 43% (238/560) participated.

ASSESSMENT OF RISK FACTORS

Participants completed a questionnaire assessing health, disability, psychosocial factors and PA levels; underwent anthropometric assessment; and wore an accelerometer (Actigraph) for 7 days.

MAIN OUTCOME MEASURES

Average daily accelerometer step-counts and time spent in different PA levels. Associations between step-counts and other factors were examined using linear regression.

RESULTS

Average daily step-count was 6443 (95% CI 6032 to 6853). Men achieved 754 (84 to 1424) more steps daily than women. Step-count declined steadily with age. Independent predictors of average daily step-count were: age; general health; disability; diabetes; body mass index; exercise self-efficacy; and perceived exercise control. Activities associated independently with higher step-counts included number of long walks and dog-walking. Only 2.5% (6/238) of participants achieved the recommended 150 minutes weekly of at least moderate-intensity activity in > or = 10 minute bouts; 62% (147/238) achieved none.

CONCLUSIONS

This is the first population-based sample of older people with objective PA and anthropometric measures. PA levels in older people are well below recommended levels, emphasising the need to increase PA in this age group, particularly in those who are overweight/obese or have diabetes. The independent effects of exercise self-efficacy and exercise control on PA levels highlight their role as potential mediators for intervention studies.

Socio-economic determinants of casualty and NHS Direct use

BACKGROUND

There is limited evidence on the social determinants of A&E use and concerns over the equity of NHS Direct utilization.

METHODS

We analysed data from the 2004-05 British General Household Survey, which included 20,421 participants. Logistic regression was used to examine individual casualty use in the last 3 months and household NHS Direct use in the last year.

RESULTS

Casualty use was higher for individuals living in rented accommodation or without car access, lower income groups, unskilled manual workers, current smokers and for individuals with limiting illness. In contrast, NHS Direct use was lower in households with older residents, low income, no car access and where the head of household was from a manual occupational group, a minority ethnic group or born outside the UK. The odds ratio for use of NHS Direct for households in the lowest equivalized income quintile was 0.67 (0.55-0.81). Adjustment for limiting illness increased the effect of socio-economic factors on NHS Direct use.

CONCLUSIONS

Reduced access to A&E services will disproportionately affect poorer individuals, whereas increased investment in telephone services will benefit affluent populations. Current national policy may widen inequities in access to emergency care.

Infections presenting for clinical care in early life and later risk of hay fever in two UK birth cohorts

BACKGROUND

The 'hygiene hypothesis' proposes that infections in infancy protect against hay fever (HF). We investigated infections during infancy in relation to HF, including rarer ones not previously researched in this context, while examining the role of potential confounding variables.

METHODS

From birth cohorts derived within the General Practice Research Database (GPRD) and Doctors Independent Network (DIN) database of computerized patient records from UK general practice, we selected 3549 case-control pairs, matched for practice, age, sex and control follow-up to case diagnosis. Conditional logistic regressions were fitted for each of 30 infections; behavioural problems (BP) acted as a control condition unrelated to HF. Odds ratios (OR), adjusted for consultation frequency were pooled across the databases using fixed effect models. We also adjusted for sibship size in GPRD and a socioeconomic marker in DIN.

RESULTS

Upper respiratory tract infections, diarrhoea and vomiting and acute otitis media in infancy were each related with a moderately increased risk of HF in both databases, as were BP. These associations were lost on adjustment for consultation frequency. Only bronchiolitis was significantly associated with a reduced pooled risk of HF after adjustment for consultations (OR = 0.8). Adjustment for sibship size in GPRD and a socioeconomic marker in DIN had little impact on the OR.

CONCLUSIONS

Of 30 infectious illnesses investigated, none had strong or consistent associations with HF after adjustment for consultation frequency. Except for bronchiolitis, possibly a chance finding, none of the clinically apparent infections considered appear to have an important role in allergy prevention.

Trends in secondary prevention of ischaemic heart disease in the UK 1994 2005: use of individual and combination treatment

BACKGROUND

Statins, antiplatelet drugs, beta-blockers and ACE inhibitors may produce marked benefits in secondary prevention of ischaemic heart disease (IHD), especially in combination.

OBJECTIVE

To examine trends in treatment and factors associated with treatment using a population-based general practice database.

DESIGN

Analysis of routinely collected computerised data from 201 general practices using iSOFT software contributing to the DIN-LINK database.

SETTING AND PATIENTS

Subjects aged >or=35 years and registered with the practices; on average, 30 000 men and 21 000 women with IHD each year.

MAIN OUTCOME MEASURE

Percentage of subjects with IHD receiving individual drugs and combined treatment in any given year.

RESULTS

Between 1994 and 2005 use of drugs for secondary prevention increased markedly. By 2005, 80% of men and 70% of women were receiving a statin, 75% and 74% were receiving antiplatelet drugs, 55% and 48% were receiving beta-blockers and 57% and 51% were receiving an ACE inhibitor; 55% of men and 46% of women were receiving a statin, antiplatelet drug and either beta-blocker or ACE inhibitor, of whom just under half were receiving all four classes of drug. Gender differences were largely explained by more severe disease in men. In 2005, subjects less likely to receive combination therapy were older, had not had a myocardial infarction or revascularisation, and lacked comorbidities such as diabetes or hypertension.

CONCLUSIONS

Despite high levels of statin and antiplatelet prescribing, opportunities exist for increasing the benefits of secondary prevention, especially through the wider use of combined treatments. Future targets could usefully include combination therapy.

Vaccinations, infections and antibacterials in the first grass pollen season of life and risk of later hayfever

BACKGROUND

It has been hypothesized that early-life exposure to vaccinations, infections or antibacterials influence allergic disease development. Concurrent exposure to grass pollens may alter any effect.

OBJECTIVE

To test the hypothesis that exposure to antibacterials, vaccinations (DTP or MMR) or specific infections during the first grass pollen seasons of life influences the risk of hayfever more than at any other time of the year.

METHODS

Nested case-control studies were based on birth cohorts within two large databases of computerized patient records from UK general practices: the General Practice Research Database (GPRD) and Doctors' Independent Network (DIN). Seven thousand ninety-eight hayfever cases, diagnosed after age 2, were matched to controls for practice, age, sex and follow-up of control to case ascertainment date. Conditional logistic regression was used to compare exposure by age 1 (age 2 for MMR) inside vs. outside the grass pollen season (May, June, July). Odds ratios (ORs) were pooled across databases.

RESULTS

There were no associations in either database between MMR during vs. outside the grass pollen season and later hayfever. Of 23 infections studied, none were statistically significant; although analyses for the less common conditions were limited by low statistical power. The pooled OR for hayfever comparing exposure to antibacterials only in the grass pollen season with only outside it was 1.20 (95% CI 0.98-1.47) and for DTP was 0.84 (95% CI 0.72-0.98).

CONCLUSION

Although an interaction between early exposure to microbial agents and concurrent grass pollen exposure on hayfever risk seemed plausible, there was little evidence to support it across a range of analyses. However, the effect of DTP though weak deserves further study.

The epidemiology of medical treatment for glaucoma and ocular hypertension in the United Kingdom: 1994 to 2003

AIMS

To study trends in the prevalence of being treated for glaucoma and ocular hypertension from 1994 to 2003, and to examine factors determining treatment in 2002.

METHODS

Computerised data (the DIN-LINK database) from 131 general practices across the United Kingdom, in which half a million patients aged 40 years or more were registered annually, were used. On average 10 000 patients were treated for glaucoma and ocular hypertension annually.

RESULTS

Prevalence of being treated for glaucoma and ocular hypertension increased from 1.7% in 1994 to 2.3% in 2003. Those aged 85 years or more were 13 times (95% CI 12.2 to 13.8) more likely to be treated than those aged 40-64 years. Men were more likely to be treated than women (OR 1.24, 95% CI 1.19 to 1.28). Subjects "hard pressed" were less likely to be treated than "wealthy achievers" (OR 0.92, 95% CI 0.86 to 0.99). While use of topical beta blocker only medications has declined since 1995, use of topical prostaglandins and combination therapies has increased. In 2003, use of prostaglandins overtook beta blocker only medications.

CONCLUSION

Prevalence of being treated for glaucoma has increased over time, and rises with age. Differences in treatment by sex and social status could be explained by use of or access to health care or by underlying prevalence of disease. Trends in treated glaucoma emphasise the shift from use of topical beta blockers to newer therapies.

Differential modulation of plasma -amyloid by insulin in patients with Alzheimer disease

BACKGROUND

Hyperinsulinemia and insulin resistance are risk factors for memory impairment and Alzheimer disease (AD). Insulin regulates levels of the amyloid beta-peptide (Abeta) in vitro in neuronal cultures and in vivo in the CSF of normal older adults.

OBJECTIVE

To determine whether insulin affected plasma Abeta levels and whether such effects differed for patients with AD compared with normal older adults.

METHODS

Fifty-nine patients with AD and 50 healthy older adults each received infusions of saline and of insulin (1.0 mU.kg(-1).min(-1)) with accompanying dextrose to maintain euglycemia. A subset of participants (19 AD, 12 normal) received two additional conditions, in which insulin was infused at a lower (0.33 mU.kg(-1).min(-1)) and higher (1.67 mU.kg(-1).min(-1)) rate. Plasma insulin and Abeta were measured after 120 minutes of infusion.

RESULTS

Adults with AD had higher plasma insulin vs normal adults at the two higher infusion rates, despite receiving comparable amounts of insulin. For normal adults, insulin reduced plasma Abeta levels at the middle (1.0 mU.kg(-1).min(-1)) dose, with attenuated effects at lower and higher doses. In contrast, for patients with AD, insulin raised plasma Abeta levels at the two higher doses (1.0 and 1.67 mU.kg(-1).min(-1)).

CONCLUSIONS

These results suggest that patients with Alzheimer disease (AD) have reduced insulin clearance and insulin-provoked plasma amyloid beta-peptide (Abeta) elevation. Abnormal regulation of peripheral Abeta by insulin may contribute to AD risk.

Arterial distensibility in adolescents: the influence of adiposity, the metabolic syndrome, and classic risk factors

BACKGROUND

Atherosclerosis develops from childhood, but the determinants of this preclinical stage remain uncertain. We examined the relations of classic coronary risk factors, adiposity and its associated metabolic disturbances, to arterial distensibility (a marker of early arterial disease) in 13- to 15-year-olds, some of whom had previously been studied at ages 9 to 11 years.

METHODS AND RESULTS

Brachial artery distensibility was measured by a noninvasive ultrasound technique in 471 British children in whom measures of adiposity, blood pressure, fasting blood lipids, and insulin had been made. All adiposity measures showed strong graded inverse relationships with distensibility. Inverse associations with distensibility were also observed for insulin resistance (homeostasis model assessment), diastolic pressure, C-reactive protein, and the number of metabolic syndrome components present, which had a graded relation to distensibility. Total and LDL cholesterol levels were also inversely related to distensibility, but less strongly than adiposity; homocysteine had no relation to distensibility. Although the relations of total and LDL cholesterol and diastolic pressure to distensibility had been present at 9 to 11 years of age, those of adiposity and insulin resistance were only apparent at 13 to 15 years.

CONCLUSIONS

Adiposity and its metabolic consequences are associated with adverse changes in the arterial wall by the teenage years. The graded relation with increasing adiposity was stronger than that for cholesterol and was seen at body mass index levels well below those considered to represent "obesity." This emphasizes the importance of population-based strategies to control adiposity and its metabolic consequences in the young.

Trends in the prevalence of diagnosed atrial fibrillation, its treatment with anticoagulation and predictors of such treatment in UK primary care

OBJECTIVES

To examine trends in the prevalence of diagnosed atrial fibrillation (AF), its treatment with oral anticoagulants between 1994 and 2003, and predictors of anticoagulant treatment in 2003.

METHODS

Analysis of electronic data from 131 general practices (about one million registered patients annually) contributing to the DIN-LINK database.

RESULTS

From 1994 to 2003 the prevalence of "active" AF rose from 0.78% to 1.31% in men and from 0.79% to 1.15% in women. The proportion of patients with AF taking anticoagulants rose from 25% to 53% in men and from 21% to 40% in women. Most others received antiplatelets. The likelihood of receiving anticoagulants was greater for men and with increasing stroke risk. It decreased sharply with age after 75 years. Socioeconomic status, urbanisation and region had no influence. Non-steroidal anti-inflammatory drugs, antiplatelet drugs and ulcer healing drugs were associated with reduced likelihood of receiving anticoagulants, as were peptic ulcers, chronic gut disorders, anaemias, psychoses and poor compliance. Anticoagulant treatment was associated with several cardiovascular co-morbidities and drugs, possibly due to secondary care treatment. Nevertheless, only 56.5% of patients at very high risk of stroke were taking anticoagulants in 2003, whereas 38.2% of patients at low risk of stroke received anticoagulants.

CONCLUSIONS

This study confirms previously observed trends of increasing AF prevalence and warfarin treatment. Many patients who may benefit from anticoagulation still do not receive it, whereas others at lower risk of stroke do. The lower likelihood of women receiving anticoagulants is of particular concern.

British South Asians aged 13-16 years have higher fasting glucose and insulin levels than Europeans

AIM

To examine whether plasma glucose, insulin resistance and markers of adiposity differed between British adolescents of South Asian and European origin.

METHODS

School-based cross-sectional study (1998-2000), in which detailed measurements of adiposity, fasting plasma glucose and serum insulin were made in 90 South Asian and 1248 European pupils (overall 69% response rate).

RESULTS

Compared with Europeans, South Asian subjects had higher mean fasting insulin levels (percentage mean difference 17.2%, 95% confidence interval 7.2-26.1%, P = 0.001), a higher mean fasting glucose (mean difference 0.19 mmol/l, 95% confidence interval 0.08-0.29 mmol/l, P = 0.0005) and a higher prevalence of impaired fasting glucose (> or = 6.1 mmol/l) (5.6% vs. 1.5%, odds ratio 3.9, 95% confidence interval 1.4-10.9, P = 0.004). Although South Asian children tended to have slightly higher indices of adiposity than Europeans (other than body mass index), the differences in glucose and insulin levels persisted after adjustment for adiposity and for pubertal status.

CONCLUSIONS

The predisposition to Type 2 diabetes observed in South Asian adults is apparent before adult life. Establishing the contributions of the childhood and fetal environments and of genetic factors to the development of these ethnic differences is an important priority. Prevention of Type 2 diabetes in British South Asians needs to begin before adult life.