Marcus O. Kjelsberg

Electrocardiographic Findings Among the Adult Population of a Total Natural Community, Tecumseh, Michigan

Electrocardiograms were recorded from 2,449 men and 2,689 women past 16 years of age, 85 per cent of the adult population of Tecumseh, Michigan. The tracings were classified according to the system of Blackburn and associates and the various categories are tabulated and discussed.Abnormal Q waves and certain “nonspecific” changes such as left axis deviation, high-amplitude R waves, ST-segment depression, T-wave inversion, first-degree atrioventricular block, complete intraventricular block, and arrhythmias increased in frequency with age. Hypertension and hyperglycemia occurred with significant frequency among persons with some of these changes. It seems likely that such “nonspecific” electrocardiographic abnormalities are frequently signs of coronary or hypertensive heart disease.The mean amplitudes of QRS complexes of men less than 50 years of age were greater than those of women. Such sex differences should be taken into account in the interpretation of clinical electrocardiograms.Further examinations and surveillance of the participants of this study are expected to clarify the significance of the electrocardiographic features discussed and the relationships between such features and other physiologic variables.

Distributions and familial studies of blood pressure and serum cholesterol levels in a total community--Tecumseh, Michigan

Abstract The medical examination of the population of a complete natural community, Tecumseh, Michigan, has provided a basis for investigation of factors possibly relating to predisposition to chronic disease. The following are reported: 1. 1. Parameters for distributions of blood pressure and cholesterol values for the entire population, including young children. 2. 2. Correlations between parents and children within specific age groups and by age-sex adjusted scores; these are relatively low, but consistently positive, being considerably greater for cholesterol than for blood pressure. Thus, there was a distinct resemblance in values between parents and children but the force of similarity was essentially equal over the entire range of distributions of blood pressure and cholesterol. Children resembled mothers and fathers equally in regard to blood pressure, but had some tendency to be more like their mothers in their cholesterol values. 3. 3. Correlations between siblings, while somewhat greater, were found to be within the same general range of magnitude as the parent-child comparisons. 4. 4. Spouse comparisons, as noted by most other investigators, showed a lack of significant correlations for either variable when all couples are viewed in the aggregate. No gradient of increasing conformity between spouses was demonstrable for either blood pressure or cholesterol when viewed by length of marriage, a rough index of the number of years of a shared environment. 5. 5. Comparisons with other studies were presented and types of possible genetic control and environmental interaction was discussed. The present findings are compatible with the concept of a multifactorial genetic and environmental interplay for both blood pressure and cholesterol.

The Relationship of Cardiovascular Disease to Hyperglycemia

Excerpt The high prevalence of vascular disease among diabetics has long been recognized and has become increasingly important since the acute complications of diabetes, acidosis, and infection hav...

Carbohydrate Tolerance and Diabetes in a Total Community, Tecumseh, Michigan: 1. Effects of Age, Sex, and Test Conditions on One-hour Glucose Tolerance in Adults

During initial examinations of the residents of Tecumseh, Michigan, one-hour 100-gm. glucose tolerance tests were applied to 2,983 persons sixteen years of age and older. Distributions of one-hour blood glucose values divided by age, sex and interval since last food were unimodal with slight skewing toward higher levels. In general, means and variances of distributions for men and women of the same age tested under like circumstances were almost identical. In contrast, age and recent food independently exerted striking effects on one-hour levels. With increasing age through the seventh decade the whole one-hour glucosemia distribution shifted steadily toward higher levels, the slope of its regression on age approximating 13 mg. per 100 ml. per decade. Persons challenged within four hours of eating exhibited one-hour values averaging 25 mg. per 100 ml. below those of similar ages challenged at longer intervals after eating. The degree of depression of the one-hour value by recent food increased detectably with the total carbohydrate intake during the last four hours. No diurnal variation was noted; seasonal variation was observed only in males, whose values were slightly higher in autumn months than in other seasons. The consistent observation of a linear age gradient challenges current diagnostic criteria for diabetes which take no account age. Instead, the present data suggest that much of what has been designated as maturity-onset diabetes results from a diminution of carbohydrate tolerance with age which is characteristic of the entire population. Accordingly, hypotheses regarding the etiology of diabetes must be rexamined.

Familial Aggregation of Factors Associated with Coronary Heart Disease

In the course of an epidemiological study covering an entire community, Tecumseh, Michigan, the familial aggregation of various levels of four variables associated with coronary heart disease-serum cholesterol, systolic blood pressure, relative weight, and blood glucose after a standard load-was assessed quantitatively by determining the relative frequencies of high, intermediate, and low levels of the variables for several familial combinations. High, intermediate, and low levels for each variable were defined in terms of quintiles (highest, middle three, lowest, respectively) of the distribution of the variable specific for age and sex.Parents and their children and siblings were compared. There was a striking resemblance between children and their fathers and mothers for all the four variables under study, as well as for height which was used as a frame of reference. The degree of resemblance between parents and children was approximately the same at the three levels-“low,” “intermediate,” and “high”-of the variables, pointing to a multifactorial mode of determination.In an attempt to assess the relative role of environmental and genetic factors with respect to the determination of the variables under study, degrees of aggregation by age were compared. An appreciable degree of resemblance was found among siblings below the age of 16 who may be presumed to share the same environment to a great extent. Aggregation was less marked for siblings between the ages of 16 and 40, a time when less of the same environment is shared, but it rose again after age 40. It is postulated that the observed rise after age 40 is due to an increase in the penetrance of the genes involved, at middle age and beyond. In addition, this pattern of aggregation suggests that environmental factors may play a stronger role prior to middle age. A similar subdivision by age, was used to study relationships between parents and children; although no corresponding differences between age groups were found, this apparent inconsistency with the sibship data could be explained, in part, by differences in age composition of the groups involved.The practical implication of the foregoing pattern of familial aggregation lies in the possibility of specifying for an individual the risk of developing high values of a variable predisposing to coronary heart disease in the future on the basis of the values shown by his parents and siblings.