HIV infection in England and Wales: a changing pattern

Of 32,983 specimens from 307 sources in England and Wales tested in the Virus Reference Laboratory for anti-HIV between 1984 and 1987, 6491 (20%) were positive. Ninety-five per cent of the positive subjects were male and 44% of them were from three London genito-urinary medicine clinics. In 1987 the numbers of newly diagnosed HIV infections decreased in homosexual men and haemophiliacs and increased in injecting drug abusers; 148/1199 (12%) of all the positive findings in 1987 were in females. Between 1984 and 1987 the proportion of anti-HIV positive individuals who were asymptomatic fell by nearly 10% and the proportion with AIDS/ARC rose by nearly 10%. Of the requests leading to positive results 1280 (20%) were recognized as duplicates of previous positive results, while for 34% of the requests no clinical information was provided. These deficiencies in the data compromise HIV surveillance based on diagnostic testing, and supplementary bias-free data are needed.

Instrument flight performance under the influence of certain combinations of antiemetic drugs

Two different combinations of antiemetic drugs were evaluated using a digital flight simulator. Drug treatments consisted of a lactose placebo, a combination of thiethylperazine (10 mg) and cimetidine (300 mg), and a combination which added promethazine (25 mg) to the two-drug combination. The performance effects of these combinations were evaluated on both a dual task (instrument flight task with the Sternberg Memory Scanning task) and a single task condition (Sternberg task only) for 3 h post drug ingestion. Analysis indicated a significant treatment effect on three of the six flight performance variables and that the three-drug combination, containing promethazine, was primarily responsible for the decrease in performance. Implications for operation in a radiation environment are that thiethylperazine and cimetidine will not cause significant performance decrements, but the addition of promethazine to those two drugs will significantly impair performance. The Sternberg task was sensitive to changes in workload.

Atropine sulfate effects on aviator performance and on respiratory-heart period interactions

In this study, 20 human volunteers received a placebo and atropine doses of 0.5, 1.0, 2.0, and 4.0 mg X 75 kg-1 in a Latin Square double blind design, and effects were monitored for 3 h postinjection. The 2.0 mg and the 4.0 mg doses resulted in significant flight simulator performance decrements beginning at 1 h postinjection with only minimal recovery by 3 h postinjection. Electrocardiogram data were used to estimate the amplitude of respiratory sinus arrhythmia (RSA) which was more sensitive than mean heart period or mean heart period variance to the effects of atropine. These parasympathetic effects were relatively rapid in onset and peaked within the first 40-min period for the 2.0 and 4.0 mg doses. The onset of performance effects were delayed 1 h 40 min for the 2.0 mg and 1 h 00 min for the 4.0 mg treatment.

Comparison of the effects of atropine sulfate and ethanol on performance

The flight simulator performance decrements resulting from atropine injections were compared to similar decrements resulting from ethanol toxicosis. There were 20 volunteers that received 0.0, 0.5, 1.0, 2.0, and 4.0 X 75 kg-1 of atropine sulfate under double-blind conditions. The performance decrements at each atropine sulfate treatment level for each subject were determined by computing root mean square (RMS) deviations for five flight performance variables. The data set from a previous study concerned with the effects of ethanol on pilot performance was reanalyzed, and the decrements for the five variables at the 0.082% blood alcohol level (BAL) were computed. Probit analysis was used to estimate the effective dose (ED50) at which 50% of the subjects in the atropine sulfate experiment were expected to display decrements in excess of those observed for the 0.082% BAL. The ED50 was 3.12 mg of atropine sulfate.

Leisure time physical activity and its relationship to coronary risk factors in a population-based sample. The Minnesota Heart Survey

Energy expenditure in leisure time physical activity was measured using the Minnesota Leisure Time Physical Activity Questionnaire in a probability sample of 25- to 74-year-old residents of the seven-county metropolitan area of Minneapolis-St. Paul, Minnesota. Geometric mean estimates of leisure time physical energy expenditure were 193 kcal per day for men and 111 kcal per day for women. Only 34% of men and 17% of women expended 2,000 kcal or more per week in leisure time physical activity. Energy expenditure, especially in heavy intensity activities, declined with age, more so for women than men. Significant associations were observed between leisure time physical activity, particularly heavy intensity activity, and other coronary heart disease risk factors. Greater heavy intensity activity was associated with higher education (r = 0.14 to 0.26), greater Type A behavior (r = 0.14 to 0.15), higher serum high density lipoprotein (HDL) cholesterol levels (r = 0.09 to 0.10), lower serum thiocyanate (r = 0.10 to -0.14), lower body mass index (r = -0.10 to -0.11), lower heart rate (r = -0.07 to -0.10), and lower systolic blood pressure (r = -0.06 to -0.09). Thus, although energy expenditure was generally low in this population, greater leisure time physical activity for the most part was associated with lower coronary risk factors.

Measuring the effects of neurotoxicants on flight simulator performance

The Aviation Research Laboratory has developed a methodology for evaluating toxicant effects on pilot performance. Flight data are collected using a digital flight simulator, the ILLIMAC (ILLInois Micro Aviation Computer), during holding patterns and instrument landing system approaches. The flight data are recorded by a separate microcomputer, which also presents the Sternberg memory searching task. A preliminary study examined pilot performance in the simulator and cholinesterase inhibition by insecticides in agricultural pilots. The correlation between the physiological parameters and the pilot performance data was determined. Experiments are planned to determine the effects of a variety of drugs on pilot performance. Neurotoxicants to be studied include ethanol, three antiemetic drugs, and atropine sulfate.

Dietary measures of physical activity

The relationships between cardiovascular fitness, body fatness, and the number of calories required to maintain stable body weight over a baseline period of three weeks were studied in 21 healthy obese males aged 20-44 years who participated in a controlled feeding experiment at the Division of Epidemiology (formerly the Laboratory of Physiological Hygiene) of the School of Public Health, University of Minnesota, in August 1980-June 1981. statistically significant relationships were found between the number of calories actually consumed per kg of body weight (kcal/kg) and body fatness (r = -0.79, p = 0.001), and number of calories consumer per kg of body weight and physical work capacity (VO2 max) (r = 0.76, p = 0.001). Using body fatness quartiles, the caloric intake per kg of body weight and VO2 max decreased progressively as body fatness increased through its four quartiles. These relationships were also seen when reported caloric intake from a three-day food record was used; however, the magnitude was attenuated. On the other hand, caloric intake unadjusted for body weight, whether actual or reported, was unrelated to both body fatness and VO2 max. To determine whether these relationships hold true for less obese subjects, the authors have also analyzed and compared their results with the data from previously reported feeding experiments done at the University of Minnesota. Correlations between body fat indices and actual caloric intake were similar for both studies. Therefore, the authors conclude that in these relatively young, healthy, and sedentary males with a wide range of body fatness and body weight, the observed relationships between caloric intake adjusted for body weight, body fatness and VO2 max reflect habitual physical activity. These data confirm epidemiologic observations of an inverse relationship between caloric intake per kg of body weight and body fatness, and provide a rationale for using caloric intake adjusted for body weight as a measure of long-term habitual physical activity. Thus, these data bolster the interpretation that an inverse relationship between caloric intake per kg of body weight and mortality reflects a positive health effect of long-term physical activity. This index may be particularly useful in large population studies.

Prevalence of overweight and weight loss behavior in a metropolitan adult population: the Minnesota Heart Survey experience

Data from two major surveys, conducted in the Minneapolis-St. Paul metropolitan area in 1973-74 and 1980-81, were used to estimate the prevalence of overweight. In 1980-81, weight history and the prevalence of dieting behaviors were also obtained. The prevalence of overweight was greater in the 1980-81 survey than in 1973-74. Increases were observed in all ages in women, but only in the 40-59 year age ranges in men. In 1980-81, dieting to control weight was widely reported by both sexes, even among those who had never been overweight. Of those who reported having been overweight, approximately one-third reported they had successfully reduced. More men than women reported having been overweight, but more women reported having dieted to lose weight. Formal weight reduction programs were used much more by women than men. Although most dieting attempts consisted of balanced, reduced calorie regimens, a significant percentage were "fad" types, whose nutritional safety may be questioned. Overall, contrary to findings based on clinical populations, weight reducing efforts often appear to be successful. Nevertheless, overweight remains a significant public health problem in this community.

The effect of "usual care" on cardiovascular risk factors in a clinical trial

The use of referral to "usual care" (UC) for participants in randomized clinical trials satisfies the need for a control group who receive medical attention at the level of community standards. However, it has been suggested that this method, which may include follow-up with multiple examinations to collect trial information, may actually enhance quality of care. To determine the effect of this UC status, 64 UC men from the Multiple Risk Factor Intervention Trial (MRFIT) were matched on serum cholesterol (SC), diastolic blood pressure (DBP), and age with men who had similar characteristics at the initial recruitment screening but were not selected for the trial. Both groups were remeasured an average of 45 months after the initial recruitment. DBP at the second measurement was lower in both groups (11 mm Hg) and did not differ between groups. The percentage taking blood pressure medications was similar. SC was unchanged in either group. Reduction in risk observed in this MRFIT usual care group appears to be related to improved preventive practice in the community, specifically in blood pressure treatment. The additional effect of participation in a clinical trial as a control subject appears minimal for these risk characteristics.

Sudden death and acute myocardial infarction in a metropolitan area, 1970-1980. The Minnesota Heart Survey

To determine the causes of the nationwide decline in deaths due to coronary heart disease, the Minnesota Heart Survey enumerated coronary deaths among persons 30 to 74 years old in Minneapolis-St. Paul. The survey also ascertained rates of hospitalization and case fatality during hospitalization for acute myocardial infarction. For deaths occurring between 1970 and 1978 that were due to coronary heart disease, the rates outside the hospital declined by 43 per cent in men and 40 per cent in women, and the rates in hospital emergency rooms increased by 311 per cent in men and 200 per cent in women. In both these years about two thirds of all such deaths occurred outside hospital wards. Between 1970 and 1980, hospitalization rates for acute infarction in persons 30 to 74 years old declined 8 per cent among men and 26 per cent among women, and case fatality in the hospital in persons 45 to 74 years old declined 29 per cent in men and 27 per cent in women. These changes are probably due to the combined influence of changes in risk factors in the population and improved care of patients with acute myocardial infarction before and during hospitalization.

Improvement in hypertension detection and control from 1973-1974 to 1980-1981. The Minnesota Heart Survey experience

Blood pressures from a 1980-1981 survey of 1,656 adults in Minneapolis-St Paul were compared with BPs from a similar community survey of 3,475 adults conducted in 1973-1974. Mean age-adjusted BPs in 1980-1981 were 3 mm Hg lower for men and 2 mm Hg lower for women than in 1973-1974. Hypertension prevalence, defined as diastolic BP of 95 mm Hg or greater and/or use of antihypertensive medication, was essentially unchanged. In 1973-1974, however, only 40.4% of hypertensive persons had adequately controlled BPs, 13.7% were treated but had conditions that were uncontrolled, 20.4% had known hypertension but were untreated, and 25.5% had previously undetected hypertension. In 1980-1981, the respective percentages were 76.1%, 8.5%, 8.8% and 6.6%. These impressive changes in hypertension detection and control may have contributed to the recent decline in cardiovascular disease mortality in this community.

Plant antitumor agents, 19. Novel triterpenes from Maprounea africana

Four new pentacyclic triterpenes have been isolated from Maprounea africana. These triterpenes are members of the previously unknown urs-12-en-29-oic acid series. The structures of these compounds were deduced from spectral and chemical evidence. The parent compound, maprounic acid, was identified as 3B-hydroxyurs-12-en-29-oic acid. The remaining three triterpenes were identified as maprounic acid 3-p-hydroxybenzoate, 7 beta-hydroxymaprounic acid 3-p-hydroxybenzoate, and 2 alpha-hydroxymaprounic acid 2,3-bis-p-hydroxybenzoate. Of the four triterpenes, only the 7 beta-hydroxy derivative exhibited in vivo P-388 activity.

Performance of chronically implanted induction-powered oscillator epidural pressure transducers

✓ Chronic measurements of epidural pressure made with an induction-powered oscillator transducer revealed several problems with the current design of the device. All transducers failed over a period of months due to the diffusion of extracellular fluid through epoxy seals, which resulted in corrosion of the electrical components. Significant fibrosis occurred around the circumference of the burr hole, which reduced the sensitivity of the transducers. Design modifications are suggested to circumvent these problems.

Indices of obesity and blood pressure in young men followed 32 years

In order to assess the effects of baseline indices of obesity, lean body mass, blood pressure, and weight change on future blood pressure, 112 former college men were examined 20 and 32 years after initial examination at age 20.5 (+/- 2) yr. Baseline body weight, relative body weight, body mass index and body density all showed similar significant correlations with baseline systolic blood pressure (r = 0.35, 0.31, 0.30 - 0.31) but not baseline diastolic blood pressure (r = 0.13, 0.07, 0.10 - 0.11) or follow-up blood pressure. Changes in body weight, relative body weight, body mass index and sum of skinfolds were significantly correlated with change in both systolic and diastolic blood pressure. Baseline systolic blood pressure was the most powerful predictor of 20- and 32-yr follow-up systolic (r = 0.57, 0.42), but baseline diastolic was a much weaker correlate of follow-up diastolic blood pressure (r = 0.24, 0.18).

The relationship of body fat weight, determined densitometrically, to relative weight and triceps skinfold in American youths, 12-17 years of age

The relationship between fat weight, measured densitometrically, and the triceps skinfold and Quetelet's Index has been analyzed by means of linear regression analysis of 235 American youths, 12-17 years of age; 48 males and 41 females were from Minneapolis and 121 males and 25 females from the Greater Philadelphia area. Validation was accomplished by using the results of 10 separate regression analysis, each on 90% of the sample, the remaining 10% serving in each instance as the validation group; this is known as the Jackknife Method. When the Minneapolis and Philadelphia components were pooled, suitable regression models were derived with standard deviations of the errors of prediction of 3.330 kg in males and 2.056 in females. When the sample was subdivided by city the SD's remained essentially the same, but the mean errors were larger. It is concluded that the linear regression models can be used on closely similar populations to estimate fat weight for groups, but estimates for individuals may be expected to have an error of +/- 5-6 kg (i.e., 2 SD's) and are therefore not likely to be suitably accurate for use. The regression weights indicate a greater contribution of the triceps skinfold to fat weight than of Quetelet's Index in males. In females the reverse was found. This may affect sex differences in prevalence rates of obesity, if the diagnosis is based upon a single anthropometric indicator.

Blood lipids in young men followed 32 years

The relationship of baseline characteristics to serum cholesterol at baseline (CHL47) when aged 16-25 (mean 20.5) yr and at 32-yr follow-up (CHL79) was assessed in 162 men. Mean CHL rose over the follow-up period. CHL47 predicted CHL79 (r = 0.61, p less than 0.001) but not CHL79-CHL47. The mean (+/- SD) weight change (DW) was 12.0 kg (+/- 26.0 kg). DW was not significantly related to CHL47, but was independently related to CHL79-CHL47 (4 = 0.30, p less than 0.001). Age, height, DW, any of 7 measures of baseline obesity and CHL47 predicted CHL79 with R2 of 0.40 and CHL79-CHL47 with R2 of 0.37. Thus, weight change but not baseline relative weight was a determinant of serum cholesterol change from youth to middle age. There was strong tracking of serum cholesterol over this period.

Longitudinal study (32 years) of exercise tolerance, breathing response, blood pressure, and blood lipids in young men

Changes in exercise tolerance, blood lipids, and blood pressure from youth to middle age was studied in 106 subjects followed 32 years. In addition, the responses to cold pressor and CO2 stress were studied as correlates of future lipids and blood pressure. Treadmill exercise test, cold pressor test, response to breathing a mixture of 6% CO2, and 21% O2, for 5 minutes, blood pressure, and lipid measurements were performed in 1947 when subjects were 20 +/- 2 years old. Exercise, blood pressure and lipid tests were repeated in 1979. Tracking of blood pressure and pulse response to exercise over the period was demonstrated. Baseline exercise response correlated with future blood pressure, cholesterol, triglycerides, and high density lipoproteins. Change in exercise pulse rate over the period correlated with change in cholesterol. Cold pressor systolic blood pressure response correlated with future systolic blood pressure and triglycerides. Pulse and blood pressure response to CO2 breathing correlated with cholesterol, triglyceride and high density lipoprotein 32 years later. These correlations were independent of baseline values of the variables and body mass index. Individuals who were judged "fit" (exercise pulse rise less than median) at both baseline and follow-up had the best cardiovascular risk profile (blood pressure and lipids). Blood pressure and pulse response to exercise tracked between ages 20 and 50. Exercise, cold pressor, and CO2 responses in youth correlated with blood lipid levels in middle age.

Relationship of physical characteristics and life habits to treadmill exercise capacity

Apparently healthy middle-aged men (n = 175) were recruited from a population sample and completed questionnaires about habitual physical activity, smoking, beverage consumption and sleep habits. Body mass index (BMI), heart rate and blood pressure were measured at rest and during submaximal exercise; frequency of ventricular premature beats (VPB) on an ECG rhythm strip; hand grip strength; and serum cholesterol. These characteristics were correlated with duration of treadmill exercise by the Bruce protocol. Univariate analysis indicated that treadmill performance was significantly and positively correlated with leisure-time physical activity and personal reports of sweating and/or dyspnea occurring regularly during such physical activity. Performance was negatively correlated with age, BMI, resting heart rate, cigarette smoking, and consumption of caffeine-containing beverages, but was insignificantly related to job physical activity, hand grip strength, alcohol consumption, sleep habits, blood pressure, cigar smoking, serum cholesterol, and the frequency of VPB. A 0.75 multiple correlation coefficient was found between treadmill performance and 11 of the above variables and the r is increased to 0.81 by adding heart rate during submaximal exercise. It is concluded that substantial prediction of work capacity and physical fitness of population is achieved by questionnaires and easily obtained, noninvasive physical measures.

Plasma high-density lipoprotein cholesterol: association with measurements of body mass. The Lipid Research Clinics Program Prevalence Study

Relationships between weight, height and ponderal indexes and plasma high-density lipoprotein (HDL) cholesterol and triglyceride were assessed by the Lipid Research Clinics Prevalence Study for 6865 white children and adults (3517 males and 3348 females). Overall, weight, weight/height, weight/height and weight/height were significantly and inversely associated with plasma HDL cholesterol levels and positively associated with plasma triglyceride levels. When the relationships of Quetelet index (weight/height) to HDL cholesterol were assessed by multiple regression analysis, including the explanatory variables of cigarette smoking, alcohol intake and exogenous estrogen hormone use, the Quetelet index was significantly and inversely associated with HDL cholesterol levels in children (by age 12-16 years) and adults of both sexes. After covariance adjustment for smoking, alcohol intake, hormone use and age, mean HDL cholesterol levels for individuals at the Quetelet tenth percentile were 3 mg/dl higher than for those at the fiftieth percentile, and these in turn were 3-4 mg/dl higher than for those at the ninetieth percentile. These differences in HDL cholesterol differences reported to be related to coronary heart disease mortality. Improved approaches to the primary prevention of atherosclerosis may be realized by a better understanding of the inverse relationship of body mass to HDL cholesterol levels.

Strenuous physical activity, treadmill exercise test performance and plasma high-density lipoprotein cholesterol. The Lipid Research Clinics Program Prevalence Study

During the Lipid Research Clinics North American Prevalence Study, plasma lipoprotien determinations and treadmill exercise testing were performed on 2319 white men and 2067 white women ages 20 years or older randomly selected from population surveys by nine clinics in the U.S. and Canada. Before exercise testing, participants were asked if they performed any strenuous physical activity on a regular basis. Data were analyzed to determine the relationship of plasma high-density lipoprotein (HDL) cholesterol to treadmill exercise test performance and a self-report of strenuous activity. Neither treadmill exercise test duration nor heart rate response to submaximal exercise was significantly related to HDL cholesterol levels for either men or women. However, participants who reported some strenuous physical activity generally had higher HDL cholesterol levels than those who reported none, and the more active men ages 30-49 years and active women ages 20-39 had significantly higher values (p < 0.05). When HDL cholesterol was adjusted for age, body mass index, alcohol use, cigarette smoking and interclinic population variation, more active men (47.1 vs 45.2 mg/dl; p = 0.0001) and more active women (59.6 vs 57.7 mg/dl; p = 0.02) had higher HDL cholesterol levels than their sedentary counterparts. Thus, the association between HDL cholesterol and reported physical activity was, at least in part, independent of other factors that influence HDL cholesterol concentration, but was not associated with exercise tolerance as determined by treadmill exercise testing.