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PubMed1987

Leisure-time physical activity levels and risk of coronary heart disease and death. The Multiple Risk Factor Intervention Trial.

The relation of self-selected leisure-time physical activity (LTPA) to first major coronary heart disease (CHD) events and overall mortality was studied in 12,138 middle-aged men participating in the Multiple Risk Factor Intervention Trial. Total LTPA over the preceding year was quantitated in mean minutes per day at baseline by questionnaire, with subjects classified into tertiles (low, moderate, and high) based on LTPA distribution. During seven years of follow-up, moderate LTPA was associated with 63% as many fatal CHD events and sudden deaths, and 70% as many total deaths as low LTPA (P less than .01). Mortality rates with high LTPA were similar to those in moderate LTPA; however, combined fatal and nonfatal major CHD events were 20% lower with high as compared with low LTPA (P less than .05). These risk differentials persisted after statistical adjustments for possible confounding variables, including other baseline risk factors and Multiple Risk Factor Intervention Trial group assignments. It is concluded that LTPA has a modest inverse relation to CHD and overall mortality in middle-aged men at high risk for CHD.

Adult↗

PubMed1986

A survey of 311 patients receiving ibopamine mainly during hospital treatment for severe congestive heart failure.

From a monitored release of ibopamine, the 3,4-diisobutyryl ester of N-methyldopamine, during the early Italian marketing of the drug a collection of 311 individual cases was formed. The cases were reported by 168 cardiologist-practitioners, self-selected for having a therapeutic interest in the inotropic properties of ibopamine and in trying it out in patients with mostly severe, refractory congestive heart failure (CHF). Most patients were monitored during a hospital admission for worsened CHF. After clinical reassessment and other drugs' adjustment, ibopamine was added and the patient followed-up for 20 days in hospital with regular recording of scored signs and symptoms, arterial pressure, heart rate, body weight, and any clinical event--adverse or beneficial. Concomitant drugs were also recorded. Global assessment of efficacy was mostly positive, with "ineffective" rates of only 15.9% (doctors) and 14.2% (patients). In the absence of a control group, it is impossible to determine to what extent the foregoing was really due to ibopamine or to the rest of the therapeutic policy. However, the fact that most of the severe cases had been refractory to prior treatment, and that they individually carried a grave prognosis on admission, do seem to point to real ibopamine-related benefit. The high rate of symptomatic benefit perceived by the patients would also seem likely to be drug-related. Heart rate after the ibopamine-including regimen was significantly lower than before. Systolic and diastolic arterial pressures also tended to decrease, especially in CHF of hypertensive etiology.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMedDate not supplied

Human growth hormone release is decreased during sleep in temporal isolation (free-running).

Growth hormone (hGH) secretion was measured during sleep in 10 healthy male subjects isolated from all time cues. HGH concentrations following sleep onset were compared between scheduled sleep episodes (entrainment) and self-selected sleep episodes (free-running). Peak sleep-related hGH values were decreased significantly during free-running. The duration of the first slow wave sleep (SWS) episode and the latency to the first REM sleep episode also decreased significantly during free-running. The latencies from sleep onset to SWS and to peak hGH secretion did not differ between entrainment and free-running. These results suggest that sleep-related hGH secretion begins 'on time' during free-running, but is terminated earlier. Thus, while sleep onset facilitates hGH release, the timing of other stages of sleep such as REM may alter the magnitude of sleep-related hGH secretion.

Adult↗

PubMed1986

Reduced tar, nicotine, and carbon monoxide exposure while smoking ultralow- but not low-yield cigarettes.

An unresolved public health issue is whether some modern cigarettes are less hazardous than others and whether patients who cannot stop smoking should be advised to switch to lower-yield cigarettes. We studied "tar" (estimated by urine mutagenicity), nicotine, and carbon monoxide exposure in habitual smokers switched from their usual brand to high- (15 mg of tar), low- (5 mg of tar), or ultralow-yield (1 mg of tar) cigarettes. There were no differences in exposure comparing high- or low-yield cigarettes, but tar and nicotine exposures were reduced by 49% and 56%, respectively, and carbon monoxide exposure by 36% while smoking ultralow-yield cigarettes. Similarly, in 248 subjects smoking their self-selected brand, nicotine intake, estimated by blood concentrations of its metabolite cotinine, was 40% lower in those who smoked ultralow but no different in those smoking higher yields of cigarettes. Our data indicate that ultralow-yield cigarettes do deliver substantial doses of tar, nicotine, and carbon monoxide, but that exposures are considerably less than for other cigarettes.

Adult↗

PubMed1986

Effects of a low-fat diet on plasma lipoprotein levels.

Lowering the intake of fat to decrease serum cholesterol levels has unknown effects on the proportion of cholesterol in low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Twenty normolipidemic nonvegetarians were given dietary instruction and supervision in a low-fat, semivegetarian diet for three months. Mean consumption of total fat, saturated fat, and cholesterol decreased, whereas intake of carbohydrate increased significantly on a low-fat diet. Plasma LDL levels decreased by 18% and HDL levels by 7% from prestudy baseline levels. The LDL/HDL ratio declined by 11%. Plasma triglyceride levels and body weight were unchanged. In individual subjects, the decrements in consumption of saturated fat and the increments in ingestion of polyunsaturated fat were each significantly correlated with decreases in LDL. One year after the subjects had returned to a self-selected diet, levels of dietary saturated fat and cholesterol and the plasma LDL/HDL ratio remained significantly below prestudy levels. This study and others suggest that a low-fat, high-carbohydrate diet favorably affects the plasma LDL/HDL proportion by decreasing LDL on a percentage basis 2 1/2 to three times more than it decreases HDL.

Adolescent↗

PubMed1986

Population screening for cholesterol determination. A pilot study.

A screening for plasma cholesterol levels was conducted at six sites in the New York metropolitan area and involved hospitals, health professionals, paraprofessionals, media experts, and instruments that provided cholesterol levels rapidly. During the five days of the testing, over 12,000 participants were screened. Because the program was limited to customary working hours and because of self-selection of participants, the subjects were probably an unusually health-conscious group as evidenced by the low prevalence of cigarette smokers (11%). Nevertheless, 12% were at moderate risk and 16% were at high risk for coronary heart disease. Approximately half of the population reported never having had their cholesterol levels tested, and over 40% had no idea what levels were optimal. A subsample of patients at risk was screened by telephone survey. In the majority of cases, when a patient's physician was consulted for advice, no action was recommended. Our results demonstrate that a large population screening can be implemented, that at least certain segments of the public will respond to such a program, and that educational efforts must be directed at both the public at large and physicians.

Adult↗

PubMedDate not supplied

The natural history of sensitivity to jack jumper ants (Hymenoptera formicidae Myrmecia pilosula) in Tasmania.

There are no records of the natural history of allergic reactions to "jack jumper ant" (Myrmecia pilosula) stings, but a letter to Tasmanian newspapers asked that persons who had not received prophylactic injections for such stings to report any reactions that they had experienced. Two hundred replies were received from a population of 400,000 persons, which shows that these reactions are widespread and that victims are often terrified at the thought of a further sting. Persons who responded were sent a circular and their reactions were classified. The first 100 replies were analysed: 49 persons reported an immediate generalized reaction from the first sting; 31 of these 49 persons and 18 others had a generalized reaction to further stings; and there was a tendency for local reactions at the sting site to become generalized to the whole body. Of the 15 persons who had had no reaction to a first sting, 12 claimed to have developed a generalized reaction on receiving a subsequent sting. Although self-selection may have provided an exaggerated view of the frequency with which reactions to the stings of jack jumper ants become generalized, the problem is clearly one of considerable magnitude which requires further research and attention.

Adult↗

PubMedDate not supplied

Specialties chosen by medical students who participated in a student-run, community-based free clinic.

Since 1974 the Hispanic medical and premedical students at the University of California, Davis, have operated a free clinic in a Hispanic community in Sacramento with the support and assistance of the family practice department. Using National Residency Matching Program data for the years 1978-1982, we compared the specialties selected by the students who had participated in Clinica Tepati for elective credit with those selected by all other graduating students. Almost all of the Clinica Tepati students (96.5 percent) selected one of the primary care specialties--family practice, pediatrics, and internal medicine--with 55.2 percent selecting family practice. These specialty choices of the Clinica Tepati students were significantly different from those of the other students. No cause-and-effect relationship can be determined when studying a self-selected group of students, yet the large percentage of the Clinica Tepati students selecting primary care does point toward such community-oriented experiences having some value in motivating or reinforcing a student's choice of primary care as a career goal.

California↗

PubMed1985

Avoidance of bias in cohort studies.

Cohort studies have particular advantages in confirming results of retrospective or case-control studies in those situations in which case-control studies are no longer feasible. In circumstances, the cohort study may involve randomization, thus reducing selection bias, but ordinarily there will have been self-selection by individuals as to the group in which they will fall. Investigators should analyze data from a cohort study so as to take the passage of time into account. Variables anticipated to have effects should be accounted for by stratification, if feasible, or by mathematical modeling, if necessary. Results should be interpreted with care, and qualifications should be made on any interpretations, including qualifications relating to the propriety of the mathematical model used. When long latencies are a factor, and particularly when exposure is initiated late in life, establishment of a positive role for the exposure can be difficult. Case-control and other epidemiologic studies are biased toward identification of exposures leading to outcomes of a unique nature but fail to identify more serious exposures with adverse outcomes which are more commonplace.

Clinical Trials as Topic↗

PubMed1985

Psychological and attitudinal profiles in donors for artificial insemination.

Few objective data are available concerning the psychological profiles and attitudes of sperm donors in artificial insemination programs. We studied 30 consecutive new volunteers and 45 established sperm donors using the Cattell 16PF personality profile and an attitudinal survey concerning motives for donation, attitudes toward uses of sperm, desire for knowledge of outcomes, and attitudes toward disclosures of identifying and nonidentifying information between the parties to artificial insemination. Donors differed from the population norms in 7 of 16 first-order and 1 of 4 second-order personality factors, and this difference appeared to reflect their self-selection as donors. The predominant motive for donation was altruism, but secondary motives were also common. Financial motivation was very low in this population with few students. Donors approved of all current and most hypothetical uses of sperm but were not in favor of disclosures of information to other participants in the program. Restriction of disclosures to nonidentifying details was more acceptable. Unmarried donors were more often motivated for nonaltruistic reasons and were more in favor of disclosures. Attitudes of sperm donors were mostly stable over at least 3 years, but an increasing minority with time envisaged circumstances that might lead to their withdrawal from the program.

Attitude↗

PubMed1985

Metabolic and cinematographic analysis of walking and running in men and women.

The purposes of this study were to compare the total metabolic costs and gait patterns of walking and running at self-selected, comfortable speeds in males and females. Total oxygen consumption was used to determine the metabolic cost, and cinematographic analysis was used to study the gait patterns of walking and running a distance of 1 km in 12 male and 12 female subjects. No significant sex difference was observed for the speed, vertical lift per stride, and total vertical lift per km of distance walked. Females ran at a significantly slower speed than males (P less than .01), but no significant sex difference was observed for the vertical lift per stride or total vertical lift per km of distance run. In both sexes, the gross and net energy costs of running were significantly greater (P less than .001) than those of walking when values were expressed as kcal . kg-1 . km-1 or cal . kg-1 . stride-1. No significant sex difference was observed in the gross or net metabolic cost of walking, whereas during running, the gross and net metabolic costs in kcal . kg-1 . km-1 were significantly higher (P less than .05) in females than in males. It was hypothesized that this sex difference was due to the cumulative effect of several factors which were biomechanical and metabolic in nature.

Adult↗

PubMed1985

On the perception of time during prolonged temporal isolation.

UNLABELLED: In an underground isolation unit, 42 subjects were living singly for time spans of at least 7 days up to more than a month. Except three who were entrained to 24 h by an externally controlled light-dark cycle (LD), subjects had no time cues and developed free-running circadian rhythms either in self-selected LD-cycles or in constant illumination. Each subject had to give a signal whenever he thought that 1 h had passed. In addition, 30 subjects produced short-time intervals within the range from 10 to 120 s. RESULTS: The 1-h estimates were longer than 1 h, and had a strong positive correlation with the duration of wakefulness alpha as well as with the length of the circadian cycle. The short time estimates were equally distributed between under- and over-estimation of the required interval, and they were neither correlated with the 1-h estimates nor with alpha. It is concluded that long and short time estimates are based on different mechanisms.

Adolescent↗

PubMed1985

Diet and exercise training effects on resting metabolic rate.

The decline in resting metabolic rate (RMR) during periods of caloric restriction is a well documented phenomenon. The purpose of this study was to determine if either 30 min of daily self-selected aerobic activity (Group D) or prescribed exercise training performed every other day (Group P) for 12 weeks can prevent the decrease in RMR during caloric restriction for weight loss. Seventy-eight adult subjects (38 M, 40 F) whose weights were 15-35 percent above the upper limit for age, sex and frame were randomly assigned to three treatment groups. All three groups followed the same 1200, 1500 or 1800 kcal/d (5023, 6279, 7534 kJ) diet exchange plan. Group C (Control) followed no exercise program, while D and P exercised as described above. Maximal oxygen consumption (VO2 max, m10(2)/kg X min-1) predicted from the Bruce Test increased by 0.08 +/- 7, 9 +/- 12 and 12 +/- 9 percent in groups C, D and P, respectively. The increases for D and P were significantly higher than for C (P less than 0.01). RMR (m10(2)/kg X min-1) increased by 2 +/- 9, 4 +/- 7 and 10 +/- 9 percent in groups C, D and P respectively. The percent change for group P was significantly greater than that for groups C and D (P less than 0.05). There was a significant relationship across all subjects between the % delta in VO2 max and % delta in RMR (r = 0.307, P less than 0.01). However, the association between these two variables was stronger for females than for males.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1985

Dietary chromium and manganese intakes of a selected sample of Canadian elderly women.

Energy, manganese and chromium intakes of a selected sample of 90 free-living Canadian women (mean age 66.2 +/- 6.2 years) living in a university community and consuming self-selected diets were assessed by chemical analyses of 24-h duplicate diets and via three-day dietary records, collected by the subjects. Mean gross energy intake (determined via bomb calorimetry) was 6.0 +/- 2.4 MJ (1435 +/- 580 kcal) and mean intake of manganese (determined via atomic absorption spectrophotometry) was 3.8 +/- 2.1 mg/day, respectively. Mean and median chromium intakes, analysed via instrumental neutron activation analysis were 96.4 and 77.4 micrograms/day, respectively. The manganese and chromium densities of these diets were higher compared to diets for pre-menopausal women studied earlier, attributed in part to the higher (P less than 0.0003) median intake of tea (360 g) vs 180 g for the pre-menopausal women. No significant differences between the pre and post-menopausal groups in mean intakes (in g) of any other food groups investigated, were found. Silver-plated cutlery may also be a source of adventitious chromium in the diets of these post-menopausal subjects. Nevertheless 22 per cent of the subjects had chromium intakes based on one day duplicate diets, below the US suggested safe limit, which if representative of their habitual chromium intakes, may result in chromium depletion.

Aged↗

PubMed1979

Potential effect of demographic and other variables in studies comparing morbidity of breast-fed and bottle-fed infants.

Comparing the morbidity of breast-fed and bottle-fed infants is confounded by inherent differences in breast-feeding and bottle-feeding mothers and their infants. Self-selection introduces complex variables encompassing much more than milk source used for infant feeding. Reasons for selecting breast or bottle feeding relate to demographic, socioeconomic, educational, ethnic, cultural, and psychological factors, as well as maternal and infant physical and emotional health. Many of the differences in the maternal populations may affect infant care practices, access to medical care, and infant health status. Studies published to date have not quantified these confounding effects and other potential biases in comparing morbidity to breast- and bottle-fed infants and the relationship between milk source and incidence of infantile disease remains in question. There is need for more cautious use of the available data and investigators must seek ways to design future studies to take into account the differences between breast-feeding and bottle-feeding mothers that affect both reported and actual infant morbidity.

Bottle Feeding↗

PubMedDate not supplied

[Treatment of the sick elderly in households accommodating several generations].

Multigenerational households with widowed persons aged 70 and more have been studied in order to determine the relationship between the following two groups of variables: (a) variables in the aged person describing the existence and degree of an organic mental impairment due to a dementive process and of other signs of physical illnesses. (b) variables in her daughter or daughter in law consisting of selfratings of psychosomatic complaints and of attitude-scales. Results were as follows: (a) If there were indications of personality changes due to an organic brain syndrom the relatives had a lower degree of life-satisfaction and more frequently suffered from psychosomatic symptoms and interpersonal stress than those, whose old relatives showed an unaltered personality. (b) A great number of comparisons failed to show any statistical differences. Especially severe physical illness, organic brain syndrome and the need for physical care were not related to life satisfaction, psychosomatic complaints, stress due to emotional involvement and the attitude towards home-care. Our attempt to explain the missing correlations led to the following factors: the small size of the sample, self-selection of the sample and possibly inappropriate operationalisation and measurement of variables. In respect to these results the ongoing study will be modified in some details: There will be a qualitative analysis of transcribed semi-structured interviews. The proportion of families with severely demented relatives will be increased. In an additional step we shall examine families, who have decided to transfer their old member into an institution.

Aged↗

PubMed1978

The effect of energy and nitrogen intake upon urea production in children with uremia and undernutrition.

Children with severe uremia who had anorexia were observed in a clinical study center where dietary energy and nitrogen intake could be compared with urea nitrogen production (UNPr). The children received a supplement of dextrose and amino acids at night, ate a self-selected diet and were encouraged to use carbohydrate supplements. Energy intake varied from 22 to 110 kcal/kg/day and nitrogen intake from 105 to 323 mg/kg/day. UNPr was reciprocally related to energy intake. Nitrogen intake minus UNPr, an index of nitrogen balance, was positively related to energy intake. UNPr was not related to nitrogen intake. Nitrogen intake (NI) and NI-UNPr were correlated and the slope of the regression was 1.15. We inferred from the data that low energy intakes (less than 60 kcal/kg/day) were associated with catabolic losses of body protein. Intakes above that level were associated with a low and stable rate of UNPr. The level of energy and nitrogen intake within the range observed limited the rate of nitrogen retention. Once maintenance requirements for energy and nitrogen were satisfied, the efficiency with which nitrogen was used for net protein synthesis was very high.

Adolescent↗

PubMed1979

Gastric secretory and humoral responses to anticipated feeding in five men.

It is believed that humans anticipate appetizing meals by increasing vagally mediated gastric acid secretion. Studies were conducted on 5 normal male volunteers to characterize further the secretory response to anticipated meals. Plasma gastrin and glucose levels were monitored to assess the possibility that these humoral factors participated in the observed secretory changes. Subjects were not fed for 22 hr and were intubated at 10 AM. Basal gastric collections were begun, and at 1 PM on different days, subjects either (a) selected meals of choice prepared in their presence for 1 hr before nasogastric tube withdrawal and meal ingestion or (b) were not food-teased or fed. Gastric collections were obtained every 10 min during the "test" hour (1-2 PM) during both (a) and (b) studies and titrated for gastric acid. Blood samples for plasma glucose and RIA gastrin were obtained during basal and test hours every 10 min. Pentagastrin-stimulated maximal acid output studies were conducted on all subjects on separate days. Results showed a progressive and statistically significant rise in gastric acid secretion when an appetizing, self-selected meal was anticipated. The magnitude of this rise was 55% of the mean pentagastrin-induced acid response. This acid response did not correlate with changes in plasma glucose or gastrin. The study demonstrated that pure psychic stimulation may be as effective an acid stimulant as sham feeding.

Adult↗