Synaptic targets of photoreceptors specialized to detect color and skylight polarization in Drosophila

Color and polarization provide complementary information about the world and are detected by specialized photoreceptors. However, the downstream neural circuits that process these distinct modalities are incompletely understood in any animal. Using electron microscopy, we have systematically reconstructed the synaptic targets of the photoreceptors specialized to detect color and skylight polarization in Drosophila, and we have used light microscopy to confirm many of our findings. We identified known and novel downstream targets that are selective for different wavelengths or polarized light, and followed their projections to other areas in the optic lobes and the central brain. Our results revealed many synapses along the photoreceptor axons between brain regions, new pathways in the optic lobes, and spatially segregated projections to central brain regions. Strikingly, photoreceptors in the polarization-sensitive dorsal rim area target fewer cell types, and lack strong connections to the lobula, a neuropil involved in color processing. Our reconstruction identifies shared wiring and modality-specific specializations for color and polarization vision, and provides a comprehensive view of the first steps of the pathways processing color and polarized light inputs.

Prevalence of undiagnosed Type 2 diabetes and impaired fasting glucose in older British men and women

AIM

To estimate the prevalence of undiagnosed diabetes and impaired fasting glucose in older British men and women, using the 1999 World Health Organization (WHO) thresholds based on fasting glucose measurements.

METHODS

Participants in the British Regional Heart Study and the British Women's Heart and Health Study were selected from one socially representative general practice in 24 British towns. Included in this analysis were 3736 men and 3642 women aged 60-79 years (predominantly white), who provided a single fasting blood sample at a clinical examination between 1998 and 2001, and who had no previous diagnosis of diabetes.

RESULTS

Two hundred and eleven men (5.7%) and 190 women (5.2%) had a fasting blood glucose level consistent with the WHO threshold for a diagnosis of diabetes (> or = 7.0 mmol/l), whilst a further 667 men (17.9%) and 642 women (17.6%) had impaired fasting glucose levels (6.1 < or = 7 mmol/l). When analyses were restricted to subjects who had fasted for at least 8 h, and whose blood sample was taken before 12.00 h, the predicted prevalence of undiagnosed diabetes (based on two separate measurements) was 6.7% in men and 6.0% in women. The predicted prevalence of impaired fasting glucose (based on two separate measurements) was approximately 20% in both sexes.

CONCLUSIONS

More than one-fifth of older white British men and women have either undiagnosed diabetes or impaired fasting glucose according to new WHO criteria. Strategies for the primary and secondary prevention of Type 2 diabetes among older individuals are urgently needed.

Non-attendance at re-examination 20 years after screening in the British Regional Heart Study

BACKGROUND

Maintenance of high participation rates in longitudinal studies is critical to their validity because of the possibility of bias associated with non-participation, which may differ between studies. This paper examines factors associated with participation status over time, by comparing the characteristics of non-attenders and attenders at a 20 year follow-up examination in a cardiovascular cohort study with an initial participation rate of 78 percent.

METHODS

A baseline examination was carried out between 1978 and 1980 and subjects have been followed up through regular reviews of general practice records, postal questionnaires, and a clinical re-examination of survivors in 1998-2000. Data obtained by questionnaire in 1996 (Q96) and at baseline examination have been used to compare the characteristics of these recent non-attenders and attenders who remain in the cohort for further follow-up.

RESULTS

The non-attendance rate of available survivors at re-examination was 23 per cent (n = 1313). Rates of non-attendance were highest in Scotland and lowest in Southern England. Non-attenders were older than attenders, more likely to smoke, and reported more disabling conditions and greater use of multiple medications at Q96, but recalled similar rates of diagnosed coronary heart disease. Marked differences in social factors were identified. Total mortality rates within 1 year of re-examination were over three times higher amongst non-attenders than attenders.

CONCLUSIONS

Non-attendance is related to health status, risk factor status and social circumstances and may affect some estimates of disease prevalence, but does not appearto have a major impact on the estimated prevalence of coronary heart disease. Information collected on non-attenders in longitudinal studies helps to estimate, adjust and minimize these effects.

Validation of patient recall of doctor-diagnosed heart attack and stroke: a postal questionnaire and record review comparison

Few studies have assessed the accuracy of patient recall of doctor-diagnosed heart attack and stroke on postal questionnaire, yet such data are widely used in epidemiologic studies. In the national prospective British Regional Heart Study of 7,735 men aged 40-59 years, based in general practice and followed up for a mean 13.8 years, a mailed questionnaire was sent to all available survivors in 1992. Patient recall of doctor-diagnosed heart attack and stroke was compared with the 316 new general practice-reported heart attacks and 102 new general practice-reported strokes from the medical record reviews. Both study and general practice records were checked for all discordant findings, and corrections were made to the study database. Patients tended to overrecall major cardiovascular events more than they underrecalled them, 33% versus 6% for heart attacks and 25% versus 11% for strokes. Among overrecalled heart attacks, other circulatory problems were present in 78% of the subjects; transient ischemic attacks accounted for 57% of overrecalled strokes. In contrast, the general practice record review system tended to underreport events rather than to overreport them, 3% versus 0.3% for heart attacks and 23% versus 5% for strokes. Patient recall of doctor-diagnosed heart attack and stroke provides a useful method for estimating prevalence rates and resource needs, but the tendency to overestimation needs to be recognized. In etiologic studies when strict diagnostic case criteria are essential, patient recall should be used to complement rather than to supplant medical record data.

Prospective study of risk factors for development of non-insulin dependent diabetes in middle aged British men

OBJECTIVE

To determine the risk factors for noninsulin dependent diabetes in a cohort representative of middle aged British men.

DESIGN

Prospective study.

SUBJECTS AND SETTINGS

7735 men aged 40-59, drawn from one group practice in each of 24 towns in Britain. Known and probable cases of diabetes at screening (n = 158) were excluded.

MAIN OUTCOME MEASURES

Non-insulin dependent diabetes (doctor diagnosed) over a mean follow up period of 12.8 years.

RESULTS

There were 194 new cases of non-insulin dependent diabetes. Body mass index was the dominant risk factor for diabetes, with an age adjusted relative risk (upper fifth to lower fifth) of 11.6; 95% confidence interval 5.4 to 16.8. Men engaged in moderate levels of physical activity had a substantially reduced risk of diabetes, relative to the physically inactive men, after adjustment for age and body mass index (0.4; 0.2 to 0.7), an association which persisted in full multivariate analysis. A nonlinear relation between alcohol intake and diabetes was observed, with the lowest risk among moderate drinkers (16-42 units/week) relative to the baseline group of occasional drinkers (0.6; 0.4 to 1.0). Additional significant predictors of diabetes in multivariate analysis included serum triglyceride concentration, high density lipoprotein cholesterol concentration (inverse association), heart rate, uric acid concentration, and prevalent coronary heart disease.

CONCLUSION

These findings emphasise the interrelations between risk factors for non-insulin dependent diabetes and coronary heart disease and the potential value of an integrated approach to the prevention of these conditions based on the prevention of obesity and the promotion of physical activity.

Casual urine concentrations of sodium and potassium and geographic blood pressure variations in Great Britain

The associations between blood pressure and urine sodium, potassium and creatinine have been studied among 1,240 men and 1,119 women living in nine British towns in order to assess the contribution of sodium and potassium intake to geographic BP variations within Great Britain. Significant positive associations were found between systolic BP and the urine sodium/potassium ratio for men (P less than 0.05) and for women (P less than 0.001), and for the sodium/creatinine ratio in men (P less than 0.01), after adjustment for age and body mass index. The findings for diastolic BP were similar, but non-significant for men. Associations between BP and sodium concentration were inconsistent and non-significant. The associations between BP and potassium concentration were consistently negative, and significant for diastolic in women (P less than 0.01). The correlations between the mean town systolic BPs and the sodium/potassium ratio were 0.65 (P = 0.058) for men, and 0.60 (P = 0.086) for women. Correlations for diastolic BP were such smaller. The association between BP and the sodium/potassium ratio in this study is consistent both within and between populations, although more so for women than for men. The results are also consistent with the results of other population studies using casual and 24 urine specimens. Although unable to quantify the effects of sodium and potassium with precision, the study suggests that the sodium/potassium ratio is of importance in geographic BP variations in Great Britain, at least for systolic blood pressure.

Migration and geographic variations in blood pressure in Britain

OBJECTIVE

To evaluate the relative contributions of factors acting at different stages in life to regional differences in adult blood pressure.

DESIGN

Prospective cohort study (British regional heart study).

SETTING

One general practice in each of 24 towns in Britain.

SUBJECTS

7735 Men aged 40-59 years when screened in 1978-80 whose geographic zone of birth and zone of examination were classified as south of England, midlands and Wales, north of England, and Scotland. Non-migrants (n = 3144) were born in the town where they were examined; internal migrants (n = 4147) were born in Great Britain but not in the town where they were examined; and international migrants (n = 422) were born outside Great Britain.

MAIN OUTCOME MEASURES

Systolic and diastolic blood pressures and height.

RESULTS

Regardless of where they were born, men living in the south of England had lower mean blood pressures than men living in Scotland (142.5/80.1 v 148.1/85.2 mm Hg). The effects of the place of birth and place of examination on adult blood pressure were examined in a multiple regression model. For internal migrants the modelled increase in mean systolic blood pressure across adjacent zones of examination was 2.1 mm Hg (95% confidence interval 1.3 to 2.9); for adjacent zones of birth the corresponding increase was 0.1 mm Hg (-0.7 to 0.7). The place of examination seemed to be a far more important determinant of mean adult blood pressure than the place of birth. Height is an accepted marker of genetic and early life influences. Regional differences in height were therefore analysed to test whether the multiple regression model could correctly distinguish between the influence of place of birth and place of examination. As expected, men born in Scotland were shorter on average than men born in the south of England irrespective of where they lived in Britain (172.6 cm v 175.1 cm for internal migrants).

CONCLUSION

Regional variations in blood pressure were strongly influenced by where the men had lived for most of their adult lives rather than by where they were born and brought up. Among middle aged men, factors acting in adult life seemed to be more important determinants of regional differences in blood pressure than those acting early in life such as genetic inheritance, intrauterine environment, and childhood experience.

Geographical variations in blood pressure in British men and women

Geographical variations in blood pressure have been studied using an automatic sphygmomanometer in 2596 men and women aged 25-29, 40-44 and 55-59 living in nine British towns. In males aged 40-59, systolic blood pressure showed a range in age-adjusted town means of 9.0 mmHg (p less than 0.05); in females the difference of 8.6 mmHg was not significant (p = 0.14). Mean arterial pressure (MAP) and diastolic at age 40-59 were significantly different between towns for both sexes. Differences at age 25-29 were of a similar magnitude, and the mean town blood pressures at 25-29 correlated highly with those at 40-59 [systolic; males r = 0.74 (p less than 0.05), females r = 0.65 (p = 0.059)]. The ranking of town blood pressures in an earlier study was reflected in the present study, but stronger associations were observed with cardiovascular mortality. It is concluded that geographical blood pressure variations in Britain are established by age 25-29 years.

Migration and geographic variations in ischaemic heart disease in Great Britain

The British Regional Heart Study seeks to explain the geographic variations in cardiovascular disease in Great Britain. A strong geographic gradient in the risk of a major ischaemic heart disease (IHD) event was found in 7735 middle-aged men who were followed up for 6.5 years. Regardless of where they were born, men examined in Scotland experienced the highest IHD risk, while those examined in the South of England had the lowest. The place of examination (ie, residence) was a more important determinant of the risk of a major IHD event than the place of birth. It seems unlikely that the geographic differences in IHD risk among middle-aged British men can be directly explained by their genetic inheritance or by their prenatal and postnatal diet.

Fluoride in the prey of barn owls (Tyto alba)

Bone fluoride in short-tailed voles (Microtus agrestis) and common shrews (Sorex araneus), the prey of barn owls (Tyto alba), was studied on Anglesey, North Wales. The average fluoride content of M. agrestis skulls obtained from a location 0.9 km from an aluminium reduction plant was significantly greater than that of skulls from another location 22 km from the source of industrial fluoride pollution. At both locations, mean fluoride levels of skulls extracted from owl pellets and those of voles trapped mechanically were broadly similar but important differences existed. Near the aluminium reduction plant, owls caught voles and shrews with a much wider range of fluoride levels than occurred at a single trapping site. However, there was no evidence for selection of heavily fluoridated prey. Within 1 km of the aluminium reduction plant, six trapping sites yielded S. araneus with a fourfold difference between the highest and lowest mean bone fluoride level.

British Regional Heart Study: cardiovascular risk factors in middle-aged men in 24 towns

The British Regional Heart Study seeks to define risk factors for cardiovascular disease, to examine their interrelationships, and to explain the geographic variations in cardiovascular disease in Britain. A clinical survey of men aged 40-59 in 24 British towns was carried out and preliminary data from the survey analysed. On a town basis cardiovascular mortality was associated with mean systolic blood pressure and the prevalence of heavy cigarette smoking and heavy alcohol consumption. No such association was seen for body mass index or mean serum total cholesterol or high-density-lipoprotein cholesterol concentration. Cigarette smoking and alcohol intake and, to a less degree, systolic blood pressure were related to the social class (percentage of manual workers) of a town, and these factors may determine to some extent the increased risk of cardiovascular disease in manual workers. Blood pressure in individual subjects was affected predominantly by age, body mass index, and alcohol intake. Body mass index appeared to affect blood pressure to a greater extent than alcohol intake and did so with a consistent and positive linear trend. Nevertheless, the differences between towns in mean blood pressure readings appeared to be more closely associated with variations in the prevalence of heavy drinking than with variations in body mass index. Alcohol intake and body mass index explained only a part of the striking differences between towns in mean blood pressure readings, and some important "town"factors remained unexplained.

Prednisolone levels in the plasma and urine: a study of two preparations in man

1. A competitive protein binding method was used to measure prednisolone and cortisol in blood and urine of volunteers given prednisolone by mouth (15 mg) in the standard tablet form and a fortnight later a regulated release formulation of prednisolone metasulphobenzoate containing an equivalent amount of prednisolone. 3. Plasma prednisolone levels rose rapidly after the standard tablet and more slowly after the regulated release form. The normal activity of the hypothalamic-pituitary-adrenal axis as measured by the 09.00 h plasma cortisol concentration was present 24 h after ingestion of the regulated release preparation. In contrast, the 09.00 h plasma cortisol level was reduced in subjects 24 h after receiving prednisolone in the standard tablet form.

Improvements in the refractometer for the correction of ametropia described in the Transactions of 1902

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A simple use of the circle of diffusion in the correction of ametropia

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Improved lantern for detecting color-blindness

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Opacity of the posterior capsule of the lens, due to the remains of the membrana vasculosa lentis

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