EcoRI-RFLP of the Apo B gene: a study in a sample group from south Italy

EcoRI restriction analysis at codon 4154 of the Apo B gene was performed in a sample of 90 subjects from southern Italy (sample S), using total blood cell DNA amplified by PCR. A group of 46 subjects from northern Italy (sample N) was also investigated for comparison. Southern Italians showed an incidence of the R2 allele (absence of the cutting site) twice as high as that found in northern Italians (48 v. 21%). By ASPCR the mutation which abolishes the restriction site was confirmed as being G----A at the first base of the 4154 codon of the Apo B gene (Glu----Lys) in both S and N samples. By studying the variability of cholesterolaemia among different EcoRI genotypes in the S sample, it was estimated that the average effect of the R2 allele is to lower serum cholesterol by 8.5 mg/dl.

XbaI-RFLP of the APOB gene in a sample group from southern Italy

The XbaI Restriction Fragment Length Polymorphism (RFLP) of the APOB gene at codon 2488 was investigated in a sample group from Southern Italy (165 subjects), taken from a population characterized by a low average level of cholesterolemia. The X2 allele (presence of XbaI cutting site), that in several groups was found to be associated with increased cholesterolemia, showed in Southern Italians a frequency of 39% which is significantly (P much less than 0.001) lower than that found in the majority of the Caucasoid groups so far tested (50%). However, an analysis of both cholesterol and APOB serum levels performed in a sample of 82 subjects, homogeneous for sex and age did not reveal any significant association between lipidemic parameters and APOB-XbaI genotypes.

Evaluation of a laboratory health examination programme in a Swedish industry (Volvo)

The records of 117 subjects, workers who had participated in a health examination at a Swedish industry, were studied retrospectively in order to find out which measures had been taken as a consequence of the results from the different examinations. The extensive laboratory examination programme that had been carried out seemed to be of limited value. It is concluded that the extensive examination programmes carried out in many industries should be re-evaluated more critically.

Environmental health: problems and prospects

Public health has benefited greatly from control of some major sources of environmental pollution, but newer and more subtle types of pollution have led to a major loss of public confidence. This has often been aggravated by the tendency of authorities to issue quite improper reassurances in order to protect their own interests, as well as by the failure of medical experts to explain risks in an intelligible way. Control measures have mainly been focused on protecting individuals from conspicuous or hazardous levels of exposure. This may be grossly insufficient if--as with radiation--the dose-response curve is considered to be linear or threshold-free: it is then the total emissions which need to be controlled, since many people exposed to a small risk may generate a large total of cases, albeit with no conspicuous risk to any one person or group. Unfortunately it is generally impossible to measure these all-important low-dose effects. Environmental policy should take account of this uncertainty.

Findings of the International Cooperative INTERSALT Study

INTERSALT, an international cooperative study on electrolytes and other factors related to blood pressure, found, in within-population analyses involving 10,079 persons, a significant positive association between 24-hour urinary sodium excretion and systolic blood pressure and between the sodium/potassium ratio and systolic blood pressure. These significant findings were derived from analyses for individuals from all 52 centers and from the 48 centers remaining when persons from four low sodium centers were excluded. Potassium excretion of individuals was significantly and independently related inversely to their systolic blood pressure. For men and women, both separate and combined, the relation between sodium and systolic blood pressure was stronger for older than younger adults, perhaps reflecting the result of longer exposure with age or diminished capacity to handle a sodium load. Relations between electrolyte excretion and diastolic blood pressure in individuals were weaker than for systolic blood pressure. Body mass index and heavy alcohol consumption of individuals were strongly and independently related to blood pressure. In cross-population analyses with n = 52 or n = 48, sample median sodium excretion was significantly and independently related to the slope of systolic blood pressure and diastolic blood pressure with age. Other ecological analyses yielded inconsistent results. Four isolated populations showed low sodium excretion, low sodium/potassium excretion, low body mass index, and low alcohol consumption; sample median blood pressures were low, there was little or no upward slope of blood pressure with age, and high blood pressure was rare or nonexistent.

Prevention of coronary heart disease: putting theory into practice

The two main approaches to delivering preventive care for coronary heart disease, ie to reducing its causal risk factors, depend upon an understanding of the major causes of this disorder. One is population based and involves educating the public in healthier behaviour and making changes in the environment to facilitate this. In the other, persons at high risk are identified and provided with individual counselling and ongoing care; the diagnostic and therapeutic components of this approach must proceed in parallel, and resources will be needed to permit this. Both strategies are necessary: they are complementary; they are not competitive either conceptually or for funding. Personal risk varies widely. Hence a system of priorities is required for phasing the provision of care according to need. High risk is mot often due to the presence of multiple risk factors but also results from single, pronounced risk factors. Those in greater need include persons with coronary disease, those with multiple sources of risk, and those with severe hypercholesterolaemia, hypertension, or diabetes. So-called selective testing differs little, in practice, from such a prioritized system of comprehensive risk factor control.

Strategies of prevention revisited: effects of imprecise measurement of risk factors on the evaluation of "high-risk" and "population-based" approaches to prevention of cardiovascular disease

Imprecise measurement of risk factors causes misclassification of individuals, limits sensitivity to detect those with high true levels, and dilutes associations between risk factors and disease. The implications of these effects for two particular examples were explored using data from a large prospective study relating plasma cholesterol to coronary heart disease (CHD) mortality and diastolic blood pressure (DBP) to fatal stroke. The absolute and relative effectiveness of three "high-risk" strategies of screening and treatment and a "population-based" shift in the risk factor distribution were compared, assuming different degrees of measurement error. The absolute benefits of each strategy were greater than suggested by unadjusted estimates from survey data. For cholesterol and CHD (a linear relationship in this cohort), uncorrected estimates tended to exaggerate the effectiveness of "high-risk" strategies relative to the "population-based" approach. For DBP and stroke (an exponential relationship), the relative effectiveness of screening and treatment was underestimated if no allowance was made for measurement error. These findings are strictly applicable only to the middle-aged men from whom they were derived, but the effects of misclassification and regression dilution need to be considered in any assessment of preventive strategies.

Follow-up study of participants in an extensive health examination programme at a Swedish industry

Two years after an extensive health examination at a Swedish industry, a follow-up study was carried out in 110 employees (94% of those initially examined). The control included a history of the subject's health, a physical examination, an electrocardiogram, urine and faeces examinations and 16 chemical analyses of whole blood or serum. Except for repeat examinations of those who had had initial values outside reference values, most of the chemical analyses meant nothing, leading to unnecessary expense and possible risk of either worried or complacent participants. The history and physical and laboratory examinations, aimed at finding factors which can be improved by changing the life style seem to be most beneficial. It is concluded that extensive health examinations, including a large number of laboratory examinations which are carried out at many industries as a health control, should be critically evaluated at these industries.

Predicting death from coronary heart disease using a questionnaire

The ten-year coronary heart disease (CHD) mortality is reported for 18,322 male civil servants aged 40 to 64 according to questionnaire responses at entry into the Whitehall study. In all 1714 died, 723 from CHD. The predictive power of the questionnaire was examined with a view to its use as a screening tool in population studies. In predicting death from coronary heart disease the greatest specificity (true negative rate) was achieved with men reporting both angina (A) and a history of severe chest pain (possible myocardial infarction, PMI). This strategy (A plus PMI) achieved a specificity of 99% but a sensitivity (true positive rate) of only 7%. In contrast, in men reporting angina and/or PMI, specificity was 90% and sensitivity 29%. If this 'and/or' algorithm was extended to include the report of dyspnoea, diabetes, and/or attending a primary care physician with heart disease or hypertension, then specificity was still 85%, but sensitivity increased to 44%. This combination (11 questions in all) is therefore recommended for screening purposes. Identifying and excluding those who favour positive answers ('yes-set' responders), using questions such as the effect of weather on breathing, led to small increases in specificity but relatively large falls in sensitivity. Among subjects reporting chest pain, those who also complained of non-specific symptoms experienced only half the mortality of those with none of these additional complaints.

Intermittent claudication, heart disease risk factors, and mortality. The Whitehall Study

In the Whitehall study, 18,388 subjects aged 40-64 years completed a questionnaire on intermittent claudication. Of these subjects, 0.8% (147) and 1% (175) were deemed to have probable intermittent claudication and possible intermittent claudication, respectively. Within the 17-year follow-up period, 38% and 40% of the probable and possible cases, respectively, died. Compared with subjects without claudication, the probable cases suffered increased mortality rates due to coronary heart disease and cerebrovascular disease, but the mortality rate due to noncardiovascular causes was not increased. Possible cases demonstrated increased mortality rates due to cardiovascular and noncardiovascular causes. This difference in mortality pattern may be due to chance. Possible and probable cases still showed increased cardiovascular and all-cause mortality rates after adjusting for coronary risk factors (cardiac ischemia at baseline, systolic blood pressure, plasma cholesterol concentration, smoking behavior, employment grade, and degree of glucose intolerance). Intermittent claudication is independently related to increased mortality rates. It is not a rare condition, and simple questionnaires exist for its detection. The latter can be usefully incorporated in cardiovascular risk assessment and screening programs.

Magnitude and causes of socioeconomic differentials in mortality: further evidence from the Whitehall Study

STUDY OBJECTIVE

The aim was to explore the magnitude and causes of the differences in mortality rates according to socioeconomic position in a cohort of civil servants.

DESIGN

This was a prospective observational study of civil servants followed up for 10 years after baseline data collection.

SETTING

Civil service offices in London.

PARTICIPANTS

11,678 male civil servants were studied, aged 40-64 at baseline screening between 1967 and 1969. Two indices of socioeconomic position were available on these participants--employment grade (categorised into four levels), and ownership of a car.

MEASUREMENTS AND MAIN RESULTS

Main outcome measures were all cause and cause specific mortality, with cause of death taken from death certificates coded according to the eighth revision of the ICD. Employment grade and car ownership were independently related to total mortality and to mortality from the major cause groups. Combining the indices further improved definition of mortality risk and the age adjusted relative rate between the highest grade car owners and the lowest grade non-owners of 4.3 is considerably larger than the social class differentials seen in the British population. Factors potentially involved in the production of these mortality differentials were examined. Smoking, plasma cholesterol concentration, blood pressure, and glucose intolerance did not appear to account for them. The pattern of differentials was the same in the group who reported no ill health at baseline as it was in the whole sample, which suggests that health selection associated with frank illness was not a major determinant. The contribution of height, a marker for environmental factors acting in early life, was also investigated. Whereas adjustment for employment grade and car ownership attenuated the association between short stature and mortality, height differences within employment grade and car ownership groups explained little of the differential mortality.

CONCLUSION

The use of social class as an index of socioeconomic position leads to underestimation of the association between social factors and mortality, which may be reflected in public health initiatives and priorities. Known risk factors could not be shown to account for the differentials in mortality, although the degree to which this can be explored with single measurements is limited.

The population mean predicts the number of deviant individuals

OBJECTIVE

To examine the relation between the prevalence of deviation and the mean for the whole population in characteristics such as blood pressure and consumption of alcohol.

DESIGN

Re-examination of standardised data from the Intersalt study, an international, multicentre study on the determinants of blood pressure.

SETTING AND SUBJECTS

Samples of adults representing 52 populations in 32 countries.

MAIN OUTCOME MEASURES

The relations, expressed as correlation coefficients, between the mean population values for blood pressure, body mass index, alcohol consumption, and sodium intake and the prevalence of, respectively, hypertension (greater than or equal to 140 mm Hg), obesity (body mass index greater than or equal to 30 kg/m2), high alcohol intake (greater than or equal to 300 ml/week), and high sodium intake (greater than or equal to 250 mmol/day).

RESULTS

There were close and independent associations between the population mean and the prevalence of deviance for each of the variables examined: correlation coefficients were 0.85 for blood pressure, 0.94 for body mass index, 0.97 for alcohol intake, and 0.78 for sodium intake.

CONCLUSIONS

These findings imply that distributions of health related characteristics move up and down as a whole: the frequency of "cases" can be understood only in the context of a population's characteristics. The population thus carries a collective responsibility for its own health and well being, including that of its deviants.

Neurobehavioral and sensory irritant effects of controlled exposure to a complex mixture of volatile organic compounds

Subjective reactions of discomfort, impaired air quality, irritation of mucosal membranes, and impaired memory have been reported in chemically sensitive subjects during exposure to volatile organic compounds (VOCs) found in new buildings. Sixty-six normal healthy male subjects aged 18-39 were exposed for 2.75 hr to a complex VOC mixture at 0 and 25 mg/m3. Each subject completed control and exposure sessions at one-week intervals in counterbalanced order. Measurements included comfort ratings of eye, nose and throat irritation, symptom questionnaire and computerized behavioral tests. Subjects found the odor of VOCs unpleasantly strong and reported that VOC exposure degraded air quality, increased headache and produced general discomfort. VOC exposure did not affect performance on any behavioral tests.

Reflections on the changing times

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The effect of danazol and the LHRH agonist analogue goserelin (Zoladex) on the biological activity of luteinizing hormone in women with endometriosis

In an attempt to determine whether the suppression in oestradiol levels caused by danazol is due to an effect on the hypothalamic-pituitary axis, we compared the endocrine effects of danazol with those of the LHRH (GnRH) agonist analogue goserelin. Serum levels of immunoreactive LH (I-LH), FSH, 17 beta-oestradiol (E2) and bioactive LH (B-LH) (using a mouse Leydig cell bioassay), were measured in ten and 20 women with endometriosis treated with danazol and goserelin, respectively. I-LH was measured both by radioimmunoassay (RIA) and immunoradiometric assay (IRMA). During 6 months of treatment with 600 mg of danazol daily, mean serum E2 decreased (P less than 0.05) to levels near the upper limit of the post-menopausal range (to a mean (and 95% confidence interval of the mean) of 117 (65-169) pmol/l) whereas FSH, I-LH (both by RIA and IRMA) and B-LH levels were not significantly altered. During 6 months of treatment with monthly depot injections of 3.6 mg goserelin, mean serum E2 decreased (P less than 0.001) to well within the post-menopausal range (to 23 (18-28) pmol/l). The mean FSH, I-LH and B-LH levels also decreased (P less than 0.05) during therapy with goserelin (from 3.9 (3.1-4.7) to 2.0 (1.6-2.4) IU/l for FSH, from 5.3 (4.5-6.1) to 1.9 (1.7-2.1) IU/l for RIA-LH, from 2.9 (2.5-3.3) to less than 0.5 (less than 0.5) IU/l for IRMA-LH and from 9.1 (7.1-11.1) to 2.9 (2.6-3.2) IU/l for B-LH).(ABSTRACT TRUNCATED AT 250 WORDS)

British perspective on the U.S. Preventive Services Task Force guidelines

The clinical approach to prevention, cogently documented in the Task Force guidelines, implies the medicalization of prevention. The concentration of resources on those most in need is efficient, the widening of physicians' responsibility is welcome, and the influence on the recipients diffuses into the community. The Task Force report, however, fails to stress the problems and the limitations of this approach. The adverse effects of "labeling" can be serious. They need to be measured and taken into account, and there should be no screening without counseling and long-term care; the latter cannot be guaranteed unless there is a comprehensive general practitioner system. Screening readily generates overmedication, particularly since many physicians lack the skills, the inclination, or the staff to provide expert and continuing health advice. Concern for high-risk individuals should be only one part of a much wider preventive strategy. This is illustrated by the close correlations between the prevalence of high-risk status and the population mean value (0.85 for hypertension vs. mean blood pressure, 0.97 for excess use of alcohol vs. population mean intake). The medical approach, important though it is, must not distract attention from the more fundamental population strategy of prevention.

Blood lead concentration, renal function, and blood pressure in London civil servants

Blood lead concentration was measured in 398 male and 133 female London civil servants not subject to industrial exposure to heavy metals. The relation between blood lead and serum creatinine concentrations and blood pressure were examined. Blood lead concentration ranged from 0.20 to 1.70 mumol/l with a geometric mean concentrations of 0.58 mumol/l in men and 0.46 mumol/l in women (p less than 0.001). In women blood lead concentration increased with age (r = +0.27; p = 0.002). In the two sexes blood lead concentration was positively correlated with the number of cigarettes smoked a day (men r = +0.17 and women r = +0.22; p less than or equal to 0.01), with the reported number of alcoholic beverages consumed a day (men r = +0.34 and women r = 0.23; p less than 0.01), and with serum gamma-glutamyltranspeptidase (men r = +0.23 and women r = +0.14; for men p less than 0.01). Blood lead concentration was not correlated with body weight, body mass index, and employment grade. In men 14% of the variance of blood lead concentration was explained by the significant and independent contributions of smoking and alcohol intake and in women 16% by age, smoking, and alcohol consumption. In men serum creatinine concentration tended to rise by 0.6 mumol/l (95% confidence interval from -0.2 to +1.36 mumol/l) for each 25% increment in blood lead concentration. In men and women the correlations between blood lead concentration and systolic and diastolic blood did not approach statistical significance. In conclusion, in subjects not exposed to heavy metals at work gender, age, smoking, and alcohol intake are determinants of blood lead concentration. At a low level of exposure, lead accumulation may slightly impair renal function, whereas blood pressure does not seem to be importantly influenced. Alternatively, a slight impairment of renal function may give rise to an increase in blood lead concentration.

Blood cadmium in London civil servants

Blood cadmium was measured in 466 randomly selected London civil servants not exposed to heavy metals at work. Blood cadmium ranged from 3.6 to 75.6 nmol/L (0.4 to 8.5 micrograms/L) with a geometric mean of 6.4 nmol/L (0.7 micrograms/L) in nonsmokers and 13.6 nmol/L (1.5 micrograms/L) in smokers (p less than 0.001). Blood cadmium was higher in women than in men (9.5 versus 7.8 nmol/L) and was inversely correlated with employment grade (p less than 0.001). The associations with age, body weight and alcohol intake were not significant. After adjusting for gender and the number of cigarettes smoked per day, 36% of the variance of blood cadmium was explained, while the contribution of employment grade was not significant. There was an unexpected negative relationship between serum creatinine and blood cadmium in men (r = -0.16; p less than 0.01). This was not true in women (r = +0.03), but the correlation remained present in men after adjustment for age, body mass index and smoking. In contrast, in the two sexes, the correlations between blood pressure and blood cadmium were weak and not statistically significant. In conclusion, in unexposed subjects, gender and smoking are important determinants of blood cadmium. In addition, a low level of environmental exposure to cadmium is not associated with a deterioration of renal function or an increase in blood pressure.

Prepartum psychosis

Four patients are described who suffered from postpartum psychosis, and also from similar episodes starting in late pregnancy. It is argued that these patients provide evidence for the prepartum onset of postpartum psychosis in a small minority of patients. The relevance of this to the aetiology of puerperal psychosis is discussed.

The Kenyan Luo migration study: observations on the initiation of a rise in blood pressure

OBJECTIVE

To demonstrate the magnitude, timing, and cause of changes in blood pressure that occur in migrants from a low blood pressure population on moving to an urban area.

DESIGN

A controlled longitudinal observational study of migrants as soon after migration as possible and follow up at three, six, 12, 18, and 24 months after migration. A cohort of controls living in a rural area who were matched for age, sex, and locality were also observed at the same periods.

SETTING

35 Villages on the northern shores of Lake Victoria in western Kenya and Nairobi.

PARTICIPANTS

325 Members of the Luo tribe aged 15 to 34 years who had migrated to Nairobi and 267 controls living in villages. The numbers of both groups reduced during follow up such that only 63 migrants and 143 controls were followed up for two years.

MAIN OUTCOME MEASURES

A medical questionnaire and three 24 hour diet histories were completed by migrants and controls. Height, weight, pulse, and blood pressure were measured. Three 12 hour overnight urine samples were collected from all participants and analysed for sodium, potassium, and creatinine concentrations.

RESULTS

The mean systolic blood pressure of migrants was significantly higher than that of controls throughout the study, and the distribution of blood pressure was shifted to the right compared with controls. The mean diastolic blood pressure of the two groups diverged over time. Blood pressure differences were not due to selective migration. The migrants' mean urinary sodium:potassium ratio was higher than that of controls (p less than 0.001) throughout, and weight and pulse rate were also higher among migrants, although differences diminished with time.

CONCLUSIONS

Urinary sodium:potassium ratio, pulse rate, and weight are important predictors of increased blood pressure among migrants from a low blood pressure community and may also be implicated in the initiation of essential hypertension.

Effects of coronary risk reduction on the pattern of mortality

Control of coronary risk factors is associated with lower age-specific risks, but people will then live longer, with increased exposure to the higher mortality rates of the elderly. Expected changes in pattern of mortality, based on the 15-year follow-up of men in the Whitehall study, have been calculated. Non-smokers live longer than smokers, but death (when it comes) is more likely to be due to heart attack and less likely to be due to cancer. By contrast a lower level of plasma cholesterol, which is also associated with longer life, is expected to reduce the lifetime risk of fatal heart attack, its place then being taken by a typical mixture of other causes of death.

Post-translational polymorphism of human IgA identified by immunoisoelectrofocusing

Immunoisoelectrofocusing (IIEF) reveals a microheterogeneity of human serum IgA controlled by an autosomal polymorphic gene, termed S. The microheterogeneity disappears when sialic acid is removed from serum glycoproteins by neuraminidase treatment. It can be postulated, therefore, that S encodes a sialyltransferase which attaches sialic acid at the outer prosthetic chains of IgA.