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Biomedical subjects

R J Garrison

Publications and source records attributed to R J Garrison.

At least 73 records · Page 4Linked to original sources
PubMed1979

The association of total cholesterol, triglycerides and plasma lipoprotein cholesterol levels in first degree relatives and spouse pairs.

HDL, VLDL, and LDL cholesterol as well as total cholesterol were measured in young adult offspring of Framingham Heart Study participants. Parental total cholesterol levels measured in the early 1950s were found to be significant predictors of present total cholesterol in the offspring. While both maternal and paternal cholesterol levels made an independent contribution to the prediction of the offspring's cholesterol, the mother's contribution was significantly greater than the father's for male offspring with a similar but less striking relationship for female offspring. The correlation for LDL cholesterol levels for siblings was higher than for HDL cholesterol or log VLDL choles terol. When adjustments were made for age, body weight, alcohol intake and cigarette smoking, slight reductions in the correlations were noted, but all adjusted correlations remained significantly different from zero. The spouse correlations for lipoproteins, however, did not differ from zero after adujustment. Since the significant association for lipoproteins in spouse pairs disappears on adjustment for correlates but the association for siblings does not, it is likely that the sibling lipoprotein associations result from either genetic or environmental factors shared early in life.

Adult↗
PubMed1978

A twin analysis of dietary intake: evidence for a need to control for possible environmental differences in MZ and DZ twins.

In the NHLI Twin Study MZ twins are shown to "get together" substantially more often than DZ twins. With this result as an indicator of differences in shared environment, the assumption of equal shared environmental variation for MZ and DZ twins is assessed using nutritional data calculated from a food frequency questionnaire. Six nutrients show significant genetic variance for the total sample. However, when stratified on the basis of how frequently twins see each other, none of the nutrients shows significant genetic variance for both strata. A similar pattern is seen for several individual items from the questionnaire. In addition, four of the nutrients show significant correlation between the absolute difference in the nutrient intake of MZ twin pairs and how often they "get together." These data appear to show that unequal environmental effects may lead to falsely high estimates of genetic variance for nutrient intake.

Adult↗
PubMed1978

Cigarette smoking and HDL cholesterol: the Framingham offspring study.

High density lipoproteins were measured on fasting blood samples from 4107 men and women. Control for reported alcohol consumption and subscapular skinfold thickness using multiple regression analysis allowed an examination of the relationship between cigarette smoking and HDL cholesterol. Cigarette smoking was found to be associated with an average difference in HDL cholesterol of about 4 mg/dl in men and 6 mg/dl in women. Furthermore, when heavy alcohol drinkers were eliminated a significant negative association between number of cigarettes smoked and HDL cholesterol was demonstrable in both men and women. There was no evidence that former cigarette smokers, with the exception of those who switched to cigars or pipes or had quit less than one year, had lower HDL levels. Cigar or pipe smokers who had never smoked cigarettes had alcohol- and skinfold-adjusted HDL cholesterol comparable to the non-smoker. These observations indicate another possible link between inhaled tobacco smoke and the atherosclerotic process and suggest the need for further studies and experiments that might clarify the mutual relationship of HDL cholesterol, cigarette smoking and the atherosclerotic process.

Adult↗
PubMed1977

The NHLBI twin study of cardiovascular disease risk factors: methodology and summary of results.

Coronary heart disease (CHD) risk factors were studied in 250 monozygotic (MZ) and 264 dizygotic (DZ) male veteran twin pairs, aged 42-56. All coronary heart disease risk factors studied showed significant correlations in both MZ and DZ twins. Substantial genetic variation was detected for height, blood pressure, glucose intolerance, uric acid, plasma triglyceride, and relative weight but little or no significant genetic variability in low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), total plasma cholesterol or hematocrit was demonstrable. These findings suggest that familial aggregation results from genetic influence on blood pressure, glucose intolerance, uric acid, triglyceride and, possibly, obesity, while largely shared environmental factors contribute to familial similarities in HDL, LDL, total cholesterol and hematocrit.

Adult↗
PubMed1976

Genetic variance in blood pressure.

The National Heart and Lung Institute Twin Study has examined 514 white adult male twin sets aged 42-56 with respect to blood pressure. The data were analyzed by a method of Christian et al. which eliminates possible biases in estimated genetic variances that could result from different total variances in MZ and DZ twins. Results of the test for the presence of genetic variance indicate that both systolic and diastolic blood pressure are to a considerable extent genetically controlled with an estimated heritability of 0.8 for systolic and 0.6 for diastolic pressure. Although these findings are at variance with some previous reports, it is thought that much of the discrepancy results from application of different analytic techniques, not in the data themselves. The application of these findings to our understanding of hypertension epidemiology and community hypertension control programs are discussed.

Adult↗
PubMed1976

Genetics of plasma cholesterol and triglycerides: a study of adult male twins.

Fasting plasma triglycerides and cholesterol, as well as cholesterol in very low density, low density and high density lipoproteins, were measured in 250 MZ and 264 DZ adult male twin pairs. A new method was used to choose an estimate of genetic variance. This includes an estimate of genetic variance for use when the total variances of MZ and DZ twins are unequal. DZ twins had greater total variance for cholesterol. When genetic variance was estimated by subtracting the within-MZ-sets mean square from the within-DZ-sets mean square, all of the lipids had significant estimates of genetic variance; however, when genetic variance was estimated by a method designed to correct bias due to unequal total variances of MZ and DZ twins, only triglycerides had significant genetic variance. The heritability of plasma triglycerides was calculated to be 0.68.

Adult↗
PubMed1975

Acquired cupping of the optic nerve head in normotensive eyes.

Clinical measurements of a horizontal cup/disc ratio were obtained among a sample of 160 normal twin subjects by stereoscopic biomicroscopy. Measurements of horizontal cup/disc ratio were normally distributed and theere was no significant association with sex, laterally, race, or refractive error in the mid-range. However, there was a significant association between size of the cup/disc ratio and age as well as intraocular pressure. After taking into account the correlation between age an intraocular pressure in normal eyes, the association between cup/disc ratio and each of these variable remained statistically significant. It is not always recoginized that the size of the normal physiological cup increases with age, and it was not previously observed that "normal" cupping occurs with age apart from the effect of pressure. The average effect of age on cup/disc ratio, amounting to an icrease of 0-0026 per year for this sample, is small. But, allowing for individual variation, some persons could show a recognizable acquired increase in cup/disc ration with age, even in the absence of glaucoma. The possibility of "normal"cupping occurring in association with age, pressure, or high myopia, alone or in combination, merits cosideration in the clinical evaluation of glaucoma suspects and serves to re-emphasize the importance of an adequate central visual field examination in the diagnosis of glaucoma. Studies are needed on the differentiatin between "normal" and "morbid" moulding of the optic nerve head.

Adolescent↗