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Biomedical subjects

D G Cook

Publications and source records attributed to D G Cook.

At least 109 records · Page 6Linked to original sources
PubMed1992

Childhood blood pressure, body build, and birthweight: geographical associations with cardiovascular mortality.

STUDY OBJECTIVE: The aim was to examine whether blood pressure, body build, and birthweight differ between areas of England and Wales with widely differing adult cardiovascular mortality rates. DESIGN: This was a cross sectional survey of children in five towns with exceptionally high and five towns with exceptionally low current adult cardiovascular mortality. SETTING: The study was a school based survey. SUBJECTS: 3842 children aged 5.0-7.5 years were selected by stratified random sampling of primary schools (response rate 76%). MEASUREMENTS AND MAIN RESULTS: Blood pressure, pulse rate, height, and weight were measured and birthweight was assessed by maternal recall. Children in towns with high cardiovascular mortality rates were significantly shorter than those in towns with low cardiovascular mortality rates (mean difference 0.9 cm, 95% confidence interval 0.4 to 1.4 cm) and had slightly higher body mass indices (mean difference 0.12 kg/m2, 95% CI -0.03 to 0.27 kg/m2). Mean birthweights were slightly lower in high mortality towns (mean difference 34 g, 95% CI -10 to 78 g), while the proportion of children with low birthweight (< 2500 g) (8.1%) was significantly higher than that in low mortality towns (5.5%) (p = 0.005). Mean differences in blood pressure between high and low mortality towns were small and non-significant, even after adjustment for height. The differences in height between high and low mortality towns were largely independent of social class. However, differences in mean birthweight were markedly reduced once social class was taken into account. CONCLUSIONS: No geographical relationship between childhood blood pressure and adult cardiovascular mortality was detected. Although it is possible that the differences in mean height and body mass index between towns with differing adult cardiovascular mortality may have implications for future patterns of health in these towns, the absence of marked differences in birthweight and blood pressure suggests that hypotheses proposing a direct relationship between intrauterine experience and adult cardiovascular mortality will have limited relevance to geographical variation in cardiovascular disease in this generation.

Adult↗
PubMed1992

Non-consulters and high consulters in general practice: cardio-respiratory health and risk factors.

The 1990 General Practitioner contract requires that health promotion and illness prevention services should be provided to all patients aged 16-74 years. Consultation rates over a period of three years were examined in 7010 middle-aged men in Great Britain to compare the cardio-respiratory health and risk factor status of non-consulters (men who did not consult in three years) with those of average consulters (men who consulted 3-5 times in three years) and high consulters (men who consulted 24 or more times in three years) to assess their relative need for health promotion and illness prevention services. The non-consulters (n = 1025) were remarkably similar to the average consulters (n = 1585) in health and lifestyle characteristics. The high consulters (n = 306) had a greater burden of ill-health and a less healthy lifestyle. Chest pain on exertion, chronic bronchitis, breathlessness or wheeze were present in 23 per cent of non-consulters, 27 per cent of average consulters and over 50 per cent of high consulters. Similarly, 48 per cent of the non-consulters smoked, drank heavily or were obese compared with 47 per cent of the average consulters and 61 per cent of the high consulters. The prevalence of recall of high blood pressure which had been diagnosed by a doctor rose from 6 per cent in non-consulters and 10 per cent in average consulters to 29 per cent in high consulters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

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.

Adult↗
PubMed1991

Identification of a reinforcement pathway necessary for operant conditioning of head waving in Aplysia californica.

The marine mollusc Aplysia californica exhibits a wide range of nonassociative and associative forms of learning. Recently, we found that the learning repertoire of Aplysia includes operant conditioning (Cook & Carew, 1986, 1989b). The behavior we examined is a naturally occurring, side-to-side head-waving response used by Aplysia in seeking food, obtaining a foothold, and egg laying. Aplysia can be operantly conditioned to reduce head-waving to one side of their body if such a response results in exposure to bright uniform-field illumination, which the animals find aversive. An essential step toward achieving a mechanistic understanding of operant conditioning is to identify and characterize the reinforcement pathway used during the learning. Toward this end, we wished to determine which of the peripheral visual pathways in Aplysia are critical for performance of the operant task. Previous experiments indicated that photic input from the optic and rhinophore nerves functionally inhibited motor neurons that participate in the operant response (head-waving), while photic input from the oral veil nerves excited these same motor neurons (Cook & Carew, 1989c). These findings suggested the hypothesis that one or both of these pathways could play an important role in mediating reinforcement during training. To explore this possibility we operantly trained animals that had received chronic bilateral transections of either the optic and rhinophore nerves or the oral veil nerves C1-C3 (in conjunction with transection of the optic and rhinophore nerves). We found that operant conditioning was not disrupted by ablation of input from the eyes and rhinophores. By contrast, ablation of input from the oral veil (together with that from the eyes and rhinophores) abolished operant conditioning. Thus, the oral veil nerves play a critical modulatory role in operant conditioning of head-waving. This observation further suggested that photic input from the oral veil is conveyed to the CNS via the oral veil nerves. In a final experiment we confirmed that stimulation of the oral veil with light evokes increased afferent activity in the oral veil nerves C1-C2. These results support the idea that the oral veil nerves contain processes that are critical components of the reinforcement pathway for operant conditioning of head-waving.

Afferent Pathways↗
PubMed1991

A critical review of the effect of factory closures on health.

The dramatic rise in unemployment in the 1970s and 1980s has led to an increase in research into the possible effects of unemployment on health. Studies of the effects of job loss are difficult to interpret because of the difficulty in ruling out selection effects--for example, the least fit may be more likely to be made redundant. The study of factory closures is appealing since all employees are made redundant and all the studies of factory closure recorded in the Index Medicus since 1980 are reviewed. None of the studies fulfil all the criteria for an ideal study, and most fail on several counts. The small sample sizes are often unavoidable, but the lack of awareness of possible selection effects often results in a biased control group of only those people who are economically active. Also, the short duration of follow up restricts the detection of possible long term effects on health. Thus the conclusions that can be drawn about the health effects of factory closures are limited. Whereas there is evidence of short term effects on mental health and of increased use of primary health care, no long term effects have been studied and objective data on physical health are almost non-existent.

Adult↗
PubMed1990

Consultation rates among middle aged men in general practice over three years.

OBJECTIVE: To provide data on consultation rates in general practice for middle aged men over three years according to their age and social class. DESIGN: Prospective study of men over eight years. Data on consultation rates during years 6-8 were collected retrospectively from practice records. SETTING: Over 1000 general practices in Great Britain by year 8. Initially (in 1978-80) the men had been selected at random from one practice in each of 24 towns. SUBJECTS: 7013 Men aged 46-65 in the sixth year of follow up. MAIN OUTCOME MEASURE: Number of consultations a year over three years. RESULTS: The mean annual consultation rate over the three years rose steadily with age (7.0 at age 46-50 to 9.7 at age 61-65) and with social class (6.4 in class I to 10.0 in class V) but was potentially misleading as the distribution was skew: 10.5% of men (736) did not consult over the three years and 17.2% (1209) consulted only once or twice, whereas 11.4% (798) of men were seen more than 18 times. The percentage of men who did not consult over three years fell only slightly with age and was unrelated to social class, with roughly a tenth of all age and social class groups not consulting. Two thirds of non-consulters in year 6 (1598/2334) consulted in year 7 or 8. CONCLUSIONS: The mean is not an appropriate summary measure of consultation rates and may conceal important differences among practices or other groups. The new general practitioner contract stipulates that all patients aged 16-74 must be provided with information to promote health and prevent illness at least once every three years. Most practices will have to approach a tenth of their men aged 46-65 specially to provide this service even if one consultation in three years is regarded as sufficient to allow a service to be provided.

Age Factors↗
PubMed1990

ABO blood group and ischaemic heart disease in British men.

OBJECTIVE: To establish whether ABO blood group is related to ischaemic heart disease on an individual and geographic basis in Britain. DESIGN: Prospective study of 7662 men with known ABO blood group selected from age-sex registers in general practices in 24 British towns. MEASUREMENTS: ABO blood group, standard cardiovascular risk factors, social class, and presence or absence of ischaemic heart disease determined at entry to study. END POINTS: Eight year follow up of fatal and nonfatal ischaemic heart disease events achieved for 99% of study population. RESULTS: Towns with a higher prevalence of blood group O had higher incidences of ischaemic heart disease. In individual subjects, however, the incidence of ischaemic heart disease was higher in those with group A than in those with other blood groups (relative risk 1.21, 95% confidence limits 1.01 to 1.46). Total serum cholesterol concentration was slightly higher in subjects of blood group A. No other cardiovascular risk factor (including social class) was related to blood group. CONCLUSIONS: Blood group A is related to the incidence of ischaemic heart disease in individual subjects. Geographic differences in the distribution of ABO blood groups do not explain geographic variation in rates of ischaemic heart disease in Britain. The findings do not support the view that ABO blood group and social class are related.

ABO Blood-Group System↗
PubMed1990

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.

Adult↗
PubMed1990

Casual urine concentrations of sodium, potassium, and creatine in population studies of blood pressure.

The relationships between blood pressure and the concentrations of urinary sodium, potassium and creatinine have been examined using casual urine specimens collected from a random sample of 1,556 men aged 40-59. Partial correlations with systolic blood pressure after adjustment for age, body mass index (BMI), alcohol consumption, and town showed that sodium was not significantly associated with BP, but potassium [r = -0.09 (P less than 0.001)] and creatinine [r = -0.07 (P less than 0.01)] were negatively associated. The sodium/creatinine ratio [r = 0.10 (P less than 0.001)] and sodium/potassium ratio [r = 0.11 (P less than 0.001)] were positively correlated with SBP. Comparable results were found throughout for diastolic pressure. Multiple regression analysis suggested that it was creatinine rather than sodium that was the important component of the sodium/creatinine ratio, and raised the possibility that potassium may play a part in this association because of the strong correlation between potassium and creatinine. Similarly, potassium appeared to be the more important component of the sodium/potassium ratio. The regression coefficients for sodium, potassium, and the sodium/potassium ratio in this study of casual urine samples were found to be similar in direction and magnitude to two large studies using 24 hour urine collections. We suggest that causal specimens may be useful for estimating sodium and potassium intake in population studies.

Adult↗
PubMed1990

Differences between observers in blood pressure measurement with an automatic oscillometric recorder.

Blood pressure measurements made with a Dinamap oscillometric blood pressure recorder by two observers on a total of 2596 male and female subjects aged between 25 and 59 living in nine British towns were examined for evidence of observer differences. After adjusting for age, body mass index and town, significant differences between the two observers were found for systolic pressure, 3.07 mmHg (P = 0.001) for male subjects and 2.08 mmHg (P = 0.036) for female subjects. Observer differences for mean arterial pressure and diastolic pressure were less than 1 mmHg and were not significant. The magnitude of observer differences also varied between towns and, when tested statistically, was significant in male subjects for systolic (P = 0.011), mean arterial (P = 0.009) and diastolic pressure (P = 0.002); for female subjects it was significant only for diastolic pressure (P = 0.023). We conclude that although the highly automated Dinamap has kept observer variation within acceptably low limits in field study conditions, the problem has not been altogether eliminated.

Adult↗
PubMed1989

Early influences on blood pressure: a study of children aged 5-7 years.

OBJECTIVE: To examine factors that influence blood pressure in children. DESIGN: Cross sectional study of children aged 5.0-7.0 years who had blood pressure measurements and for whom parental questionnaires were completed. SETTING: School based survey. SUBJECTS: 3591 Children aged 5.0-7.5 years selected by stratified random sampling of primary schools in nine British towns (response rate 72%); 3591 were examined and their parental questionnaires were completed. Data were complete for birth rank in 3559, maternal age in 3542, maternal history of hypertension in 3524, and paternal history in 2633. RESULTS: Birth weight was inversely related to mean systolic blood pressure but only when standardised for current weight (weight standardised regression coefficient -1.83 mm Hg/kg (95% confidence interval -1.31 to -2.35). Mean diastolic pressure was similarly related to birth weight. Maternal age, birth rank, and a parental history of hypertension were all related to blood pressure. After standardisation for current weight a 10 year increase in maternal age was associated with a 1.0 mm Hg (0.4 to 1.6) rise in systolic pressure; first born children had systolic blood pressure on average 2.53 mm Hg (0.81 to 4.25) higher than those whose birth rank was greater than or equal to 4; and a maternal history of hypertension was associated with a systolic pressure on average 0.96 mm Hg (0.41 to 1.51) higher than in those with no such history. The effects described were largely independent of one another and of age and social class. The relation for birth rank was, however, closely related to that for family size. CONCLUSIONS: Influences acting in early life may be important determinants of blood pressure in the first decade. The relation between birth weight and blood pressure may reflect the rate of weight gain in infancy. The reasons for the relation with birth rank and maternal age are unknown; if confirmed they imply that delayed motherhood and smaller family size may be associated with higher blood pressure in offspring.

Birth Order↗
PubMed1989

Cytomegalovirus infection and progression towards AIDS in haemophiliacs with human immunodeficiency virus infection.

To examine whether cytomegalovirus (CMV) infection could accelerate progression of human immunodeficiency virus (HIV) infection to AIDS, serological studies were done on 108 HIV-infected haemophiliacs. In the 1.3-9 years from time of first recognised HIV seroconversion, the age-adjusted risk of CDC group IV disease in CMV-seropositive patients was 2.5 times that in CMV-seronegative patients. CMV-seropositive patients were also more likely to have detectable p24 antigenaemia. Survival analysis showed that CMV-seropositive patients were at greater risk of HIV disease than CMV-seronegative patients from about 2 years after HIV seroconversion. Thus CMV infection is associated with a more rapid progression to HIV disease.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Breathlessness, angina pectoris and coronary artery disease.

The relation of breathlessness to angina was examined in 7,735 middle-aged British men. Among men who did not report breathlessness, the age-standardized prevalence rate of angina was 4%. In men with mild, moderate or severe breathlessness, the prevalence rates of angina were 16, 29 and 41%, respectively. The association between breathlessness and angina was independent of age or cigarette smoking, with similar relations observed in men who had never smoked. The prevalence of electrocardiograms revealing ischemia increased with the severity of breathlessness, even in men without angina or other evidence of coronary artery disease (CAD) at screening. In men with a low forced expiratory volume in 1 second, the prevalence of angina was also increased, but the association was much weaker than that observed between angina and breathlessness. After a 5-year follow-up, 25% of men severely breathless at screening but without any initial evidence of CAD had developed angina, 5% had had a heart attack (half of these were fatal) and 7% were dead from causes other than CAD. The corresponding rates for men not breathless at screening and without evidence of CAD were: 4% angina, 2.5% heart attack and 2% dead from causes other than CAD. Breathlessness appears to be an early indicator of CAD in the absence of either angina or electrocardiographic evidence of ischemia.

Adult↗